How to Unclog an AC Drain Line

If your home has a central air conditioning system, you may have noticed the AC drain line outside.

This pipe is located near the air conditioner’s condenser unit and it often drips water on the ground, so it’s hard to miss.

If you’ve ever wondered what’s with all the dripping, well, the drain line moves condensation from the inside air handler to the outside.

If this line clogs — and when it does, it’s usually because of algae — it can cause all kinds of problems. Like major water damage inside the house.

You can prevent a clog with simple, routine maintenance. Just pour a cup of household bleach into the AC drain line from the inside.

But once a clog forms, you can’t rely on the bleach method to do much of anything. So, attach a wet-dry vacuum to the drain line outside. (Remove the vacuum’s paper filter first.)

Then, turn on the wet-dry vacuum and suck the clog out of the pipe.

Tip: For regular condenser maintenance, clean the coils with Condenser Coil Cleaner. (This is an affiliate link. If you purchase this product, we will earn a small commission at no additional cost to you.)

Further Information


  1. Hi,

    Thanks for your advice on cleaning the a/c drain pipe. I did use a wet/dry vac and poured bleach as you described. However, I continue to hear excessive leaking into the drain pan below the unit. Should I be alarmed at this &, if so, what should I do now?

    Thanks for the help,

  2. my drain pipe is leaking considerably, but there is no water in the drip pan underneath the unit in the attic. what could cause this constant dripping of water?

  3. Hello,
    I can use some advice. A friend of mine noticed that a rubber hose that’s connected to a pipe that comes about 2 inches underneath my roof. I know it’s connected to the AC unit in my attic. My friend said allot of water seems to be coming out down that hose. So my question is – Is this normal? It was 95 outside today and 74 inside my house. The ac is working great so just checking about the excess water. Thank you

  4. Richard,
    One of the main ways an air conditioner cools your house is by removing humidity from the inside air which makes the air feel cooler. This excess moisture then flows through the drain line to the outside of your house. So what you are describing is probably a good thing. Just to be safe, I would go up in the attic and check to see if the unit is draining okay and not backing up in the pan. Also, be sure the water that is coming out is not running down the siding which might cause it to rot.

  5. Ben,
    Thank you for your advice and help. I check the pan and it’s dry so I assume everything is draining properly. With the hot weather and the dry humidity we are experiencing in Houston, Texas I just wanted to make sure the draining water was due to the weather changes. The previous owner had a rubber tube installed over the pipe piece that the water is draining out of so that the side of the house isn’t effected. Thanks again for your advice and help. I fee much assured now.


  6. I have checked to see if the pan has water in it, and it does not. Could it possibly be that the amount of water coming out the drain pipe is correct and I am concerned over nothing? It is strange to me that no water has come out of this drain pipe in 4 years, now, it is draining regularly, about a 5 gallon bucket every 2 or 3 days. It drops to the ground under the eave and is basically flooding that side of my house.

  7. Richard,
    An air conditioner in a humid climate can remove quite a bit of water, so I wouldn’t say the amount you are seeing is unusual. What is unusual is that it didn’t produce any before. To keep from flooding the area under the drain, you could attach a pipe or flexible tubing to the drain, run it down the side of your house, and then attach a hose to direct it elsewhere. By the way, the water that comes out of the AC is distilled water and is great for watering plants or a garden, so perhaps you could direct it there or to a pond or holding tank for later use.

  8. I just noticed the same problem as Richard (I’m in Fort Worth, TX). My unit is filling up a 5 gal. bucket every day. A tech came out and said he blew out “both lines” and they were fine. He noted on the sheet that the emergency and primary drain ran together and then outside the house.

    This seemed strange to me and I went and looked myself. This is a Trane handler unit in the attic. There is one white PVC pipe coming out the bottom that goes over to my master bath area. It has a removable cap on it. I removed it and it had water up inside the tube and did not appear to be draining. A second PVC pipe comes out of the unit, joins up with a PVC pipe coming out of the drain pain and then runs outside under the eave of the house. This is what has been running with water. The drain pain was dry.

    I removed the cap on the one PVC line that ran to the bath and poured about a cup of bleach (in 3 portions) in the opening. The water in it got air bubbles in it, then went down and you can see a slow trickle running in the pipe now. Also I can feel air blowing through the pipe when the cap is off and the unit running. But now, there is a very slow drip of water into the pan coming from where the PVC pipe that runs to the bath connects to the handler. Maybe I jiggled it too much. The outside pipe seems to have stopped flowing.

    So now I’m confused about what the tech said and whether I blew $85 for nothing. Wouldn’t the PVC line that runs to the master bath area be the primary drain line? Doesn’t seem like they run together to me?

  9. I need some help. My AC handler is inside a small closet in my house. The drain pipe from my AC unit is working fine, but at the floor it terminates into a larger pipe that another insulated tube runs as well. I found that insulated tube outside my house at the outside unit, but there was no larger pipe for where the drain pipe leads.

    Water is backing up out of this larger pipe at about 3-5 gallons per day and I am continually pumping it out with a wet/dry vac. How do I unclog this larger pipe from inside my house?

  10. Hi Vicky,
    I’m not sure I really found a solution to my problem. I dug a hole near the foundation and AC unit outside my house and found where the smaller pipe comes out. I snaked it and cleaned it out and filled most of the hole with drainage rock.

    So far I haven’t had any backup into the larger pipe in a few weeks. Hopefully it will stay that way. Good luck.

  11. I have the same problem, water isdripping on the pipe in the unit, but the actual end of the pipe , the other extreme, is inside the wall I guess going underground, have not access to it, shouldI just pour some bleach on the pipe and see what happens?

  12. The drain pipe for my AC is leaking. We can’t figure out why. The drain pipe is clear, no clogs, we blew it out and poured bleach in it. It worked for about 5 minutes and then started leaking again. It backs up into the pan and that leaks all over also. What is going on? This happened to us before and the excess water in the pan ended up shorting out the fan motor. So for now we’ve disconneted the drain pipe and have a bucket under it so the water can flow freely into the bucket instead of backing up into the pan. Any suggestions?

  13. I live in a condo and my drain pan was filling up and not draining to the outside. Could you tell me why this would happen as I have a brand new unit….could it be from person downstairs they have old unit. If theirs was clogged up would that back up to the 2nd floor unit???thank you

  14. I just purchased my home in July. Our A/C has been working with no problems until it started leaking 2 weeks ago. I then paid $150 for someone to clear out the line. Five days later it was leaking again. Purchased a wet/dry vac, poured some bleach in the line on the inside, and then vacuumed the line from the outside. A large amount of algae came out. This did not reslove the problem. Even tried putting my hand over the other end of the pipe for more suction. After doing this, there was a lot of suction. I thought I had it. Still leaking!! The only idea I have left is that there is something wrong with the drain line. Maybe it cracked? I have my washer close by the A/C unit and thought of having the A/C drain through there. I am running out of ideas.

  15. We have 4 A/C in three different house’s
    & in one the pan below the upstairs unit bent & leaked water in the ceiling.
    I blew the lines out with air & called the A/C owner & he said that they had had problems with the pans lately, & said that they have float valve that they had been putting on the units & he had them in stock.
    he sent a man out the next day & he put two in one house & one in another & the man could not find it in his book so he said that he would have the office call me with the bill when he got back in on monday, well they called me about two weeks later & ask for a cordite card number & then I got the invoice’s I had paid $140.00 each for the float valve & switch’s a total of $578.00. The reason the tech. could not find it in the book is that the book is the book shows P trap & all & he said that he had not installed a P trap & did not know what to charge.
    Folks The switch assy is PVC T & a switch setting in the top which shuts the unit down when the line gets stopped up the whole assy . should not have cost them over $15.00 Bulk (PVC parts are Cheap.) the moral is always ask even if you do know the people, I have known these people over 19 years.
    Another thing is 4 straps is not enough when the pan gets stopped up, I had him put two addicional straps on it (One on each side in the middle)

  16. After someone cleared out the line, another tech cut the pipe on the inside so we could clean it through there. When he was finished he put a fitting over the opening. When it backed up again after he had left, I took the fitting off and placed a bucket underneath. It started to drain normally. When I put the fitting back on it would backup. I finally left the fitting off and put duct tape around the pipe instead. I also leveled off my overflow line. I have not had a problem since.

  17. I have had problems with drain in garage floor, on very hot days when air runs alot. after reading this site…..i tried some bleach down the drain not sure whether it helped or not…no more leaks lately b ut not as hot out either ……i could nt find the outside drain that was spoken this likely the problem……could the drain line be inside the fan unit???? or underground???? trane unit.

  18. The tricky thing about AC drains is that the air handler usually operates in a negative pressure as it pertains to the drain side-which is the reason for the trap.If the trap isn’t deep enough then the water will get sucked back into the unit,then when the unit cycles off the extra water may overlow or drain so rapidly that the drain line can’t handle the amount of water.Another thing is that if the drain is longer that 10 feet after the trap-the line needs a vent after the trap so the water will not cause a siphon effect on the trap.

  19. You want your AC to drain. The pan under the unit is only as a last resort so the condensation does not damage your walls. What I have found in Texas is this, the primary drain is the closest interior drain in the house, but not the washer drain. The secondary drain is overboard. If you see water from this drain you should investigate. What I see often is the primary drain is plugged by the stem pipe not being trin at installation. If you take the drain pipe off the sink, trim it above where the AC drain is plumbed, clean out the pipe as other have stated, then tada, no more leaking outside.

  20. Hi,

    I just had a AC man out here. I replaced all the flexy ducts up in attic. Right now it is 84 degrees. I turned it on about 3 hours ago. Home is set for 70 and it is fine in the house. Problem? There is no dripping outside the pipe like last year. My question is. Is there no dripping because the house is not humid? Is that possible? Also, I did the wet vac outside like you said on the website. I went up in attic and nothing is freezing up and no water on floor. Thank you

  21. Problem? Went away on vacation for a week. Returned to find that ceiling and walls in laundry room soaked and discolored. Checked attic and found that the drain pain was full of water. Called AC tech and he blew out drain; however, the ceiling is still leaking. Any other suggestions

  22. Hello,

    My Central A/C unit is located in my utility room. It was replaced 4 years ago. Last year, I when I went to the utility room, I could hear drip, drip, drip. Apparently, the condensation pipe is not connected to drain outside, but instead, just drips steadily into my crawl space (which is sand/clay). The A/C is near a back wall, about 7 feet straight ahead; should I have a plumber (or HVAC professional), run the condensation drain pipe to the outside (could go through the foundation), or to the sump pump, which is about 30 feet away from the dripping pipe?
    Please let me know the best way to take care of this problem (most econcomical, too).

    FYI, I live in a duplex, and our units are not separate by wall. In fact, our units are right next to each other. Her pipe is dripping the same way too.
    Look forward to your prompt response.

  23. George from Austin, TX here!

    Just a tid bit of info to help a few of you out.

    If you are vacuuming the primary line with little to no luck, that probably means that the clog isn’t that well developed and not letting you get too much suction.

    Have a friend/spouse go to the AC system and plug up the bypass line with their hand (i used a 1/2 pvc cap i had lying around). This will give you a more solid suction and pull out the gunk.

    I was trying for 3 days to suck the garbage out of my drain…. bleach wasn’t working either.

    I tried the cap on the end of the line when i though that maybe the algae is built up on one side of the pipe and not letting me get a good seal.

    It literally took me 10 seconds with the cap on the bypass valve!

    Hope this helps!!!

  24. The air conditioner drain pipe in my house is enclosed and it is attached to a drain that goes under ground from inside the house. Will this drain pipe still need bleach poured in it anually?

  25. We had a man come in and fix the basment for leaking and while he was doing so he decided to fix a AC problem so he took a pipe to move the water from the unit but he only moved it about five feet away so now water pools near the side walk in my back yard and looks really ugly please help what can I do !

  26. I have a similar problem but my main drain lines drains into the wall and i assume into a vent pipe which goes to the sewer. The secondary line is dripping and there is a small amount of water in the pan. There is an access pipe into the main drain line. Will the vacuum work to suck out the clog since it is located in the attic or should I try something else?

  27. I live in a 6 unit condo building, 3 on one side, 3 on the other. I’m the middle unit. My AC unit itself (the fan part) is located outside. My furnace is located in the center of my unit next to my washer dryer. Coming out of the bottom of the furnace is PVC pipe that runs into a small “hole” in the floor, that is another PVC pipe. I can only see the top of the PVC pipe and have no clue where it runs, but it does run into the ceiling of the unit below me and outside, I assume. I looked and can’t find it. I had a guy come out 2 years ago when this happened and he said the pan needed cleaning. The guy below me complained of water on his ceiling. I looked down that pipe and saw standing water. Should I use draino or snake it or use a vacuum? Thnaks for any help.

  28. This morning I noticed condensation on all my AC vents both wall and ceiling. This has never happened before. I wipe the vents but continue to get condensation and dripping.
    I have a Trane unit and the drip pan and coils are in a sheet metal inclosure inside the unit. Should I remove the sheetmetal cover and check the pan drain? I have already cleaned the drain going outside.

  29. I had a clog in drain line from the air handler and my primary drain pan under the coils filler up and overflowed into the air handler unit and got the insulation all wet. I can’t seem to dry it out. How do I prevent mold from building up??? I can’t remove the insulation under the pan unless I remove the coil which is very expensive. Is there anything I can do about this??

  30. I am not what is going on with my pipes but there are two ‘drain pipes’ outside of my house not the one near the ac unit and it is draining alot of water out and I dont know why and where it is coming out at. Can some one help me with this? One pipe has alot of warm water coming out of it the other one dont have any water coming out.

  31. I also have the reoccurring problem of the trap getting plugged. At least once a year, I have had to crawl up into the attic and unplug the drain. I have added a pipe (with cap) to add bleach but still get the plugged trap. I just had both knees replaced and it is difficult to get up on the six ft ladder to do this maintenance. Can I eliminate the trap and use a straight pipe instead? I noticed the pipe is very loose where it fits to the AC unit. It acts more like a funnel to catch the condensation. Any negative air or vacuum would be lost anyway. Thanks for any help here and all thoughts appreciated.


  32. Note: I was wrong about the main drain line being loose and open. That Line is from the humidifier. I don’t know if that needs to be sealed or not. Again,,,, thanks.


  33. Thanks for the great information… husband is gone all the time and I’ve become the the fix it all girl! Had the AC man down the street help and he did not fix my problem…just goes to show a little research, and even a woman can do it! Bless you!

  34. Dear Danny Lipford, you should change the heading of this site to clarify that this page is not a Q&A page. This is hardly an “expert advice on home improvement” site. You forgot to mention that most modern AC systems have a primary and a secondary(backup) drain system. By telling everybody that saw condensation(water) from the drain should be alarmed, should also be told that there is most likely a primary drain that became plugged before they noticed their problem to begin with.(because they might not know the difference). I’ve read the questions here(which were not responded by Danny or his people) and these people have serious questions and needs that deserve a response fron an Expert.

  35. I recently had the annual furnace check. The tech recommended that I place another T clean out at the coil, to prevent any buildup that might occur at the site of the coil. I have a T clean out on the main drain and pout bleach into it every spring. I looked at my coil and noticed another drain connection on it (next to the primary drain) and it is capped off. Do you think that “other drain connection” will be okay to put another clean out at the coil?

  36. Our AC is dripping water… the water soaked the carpet in the room next to it and my husband states the AC drain hole that is on the floor is backed up…. he poured clorox in the hole and it came back up….. Can we put DRAINO or a solution to unclog it? And any tips on getting rid of the smell???? Help, please

  37. To prevent excess water build up and promote efficiency, every 5 years the fins and copper coils of central air unit must be cleaned by a proffessional. Costs about $300. coils are cut off, brought outside, dipped in acid to remove rust , then welded back on. Fins are simply vacuumed clean. After I had this cleaning done, there was no algae build up and very little water drained out. To maintain unit, remove cap from drain pipe and pour bleach in it once a year. If you do not have a cap then have proffessional add one.

  38. This problem was driving my wife crazy. Watched your short film and in no time at all, the clog was history. Thanks a bunch for the help.

  39. I did this today, and after I did this my ac is not draining properly causing water build up in the pan and water is now spilling out of the pan from my 2nd floor causing water damage downstairs. I rehooked the dry vac and sucked a little more, just in case something got lodged and hope this doesnt occur again. If it does, what may have happened? I luckily caught the water dripping quick enough to minimize my damage.

    • Hi Kai,
      Other than the possibility of debris in your pan being sucked into your line from the vac and forming a clog, I can’t think of any problems that would be caused by cleaning your line with bleach. I would monitor it regularly, however, to be sure it’s draining properly.

  40. Thanks. It might sound strange, but after siphoning some of the water down the pipe it started to work properly again. Not sure if there was an air bubble which just didnt allow the water to drain. It was strange, but luckily I caught it early and was able to take care of it.

  41. My drain pan is leaking on my Trane air handler. I cleared the condensation drain line, but I am still getting a signficant leak through a square opening between the primary and secondary ports. Even with the condensation line removed, I can see two very small but steady streams of water from both the primary port and the square opening. Any ideas? Thanks.

  42. I have a primary and a secondary drain. On my secondary, it goes to the floor into a little sump pump. The sump pump has no trap to clog (except for itself). I think this pump is there because its using an old drain line that is higher than the pan height as a secondary. I like it because I get lots of warning since the pump is loud and when I hear it I know my main drain is clogged. Worst case the unit will quit cooling when my hearing is gone since it has a safety float switch that is wired to the remote control wire, so if it fills all the way up and don’t drain due to clogging or a dead pump, the ac quits coming on.

  43. im in an apt. and the plumbers had been here twice to fix things. they’ve been on the bottom to check it out. then i found out my neighbors is doing it on hte same day at the same time, leaking on his carpet also.they’ve been on top of the roof to check out the situation but i dont even think they did anything because my carpet is still getting leaked on.whats happening?

  44. I’ve read all the questions on this site and I also have a clogged AC drain but do not have an outside drain. It’s all underground. I’ve not seen one answer to any of the questions posted on this site. What good does it do to post the questions if you do not give a reply to any of them.

    • Hi Judy,
      The space under each article on our website is reserved for comments that visitors would like to post. These can be general comments, feedback about the article, questions about the topic, or answers to questions posted by other visitors or staff members. While it’s not possible for Danny and the Today’s Homeowner staff to respond personally to all the comments posted on our site, we do read every one and try to help out when we can. In this article alone, you will find several answers posted from our staff as well as responses to questions posted by other visitors to the site.

      In answer to your question, since you do not have access to the end of your AC drain, you will have to attempt to clean it from where it originates at or inside the AC unit. You could try blowing out the clog with compressed air, sucking it out with a wet/dry vac, or running a small snake through the drain line. Hope this helps.

  45. I have investigated until im blue in the face but heres my issue.

    Secondary drip (overflow) line dripping outside. Drain pan is dry and never had any water in it from what I can tell. Its a newer home. (less than 2 years) Variable speed with heat pump and unit is operating fine

    With a shop vac – vac’d out the line
    with an air compressor – blew out the line
    ran some bleach down the line

    still dripping

    what am I missing?

  46. My unit is in my hall and behind the filter is where the drain hose goes into the ground….there is no pipe outside…my little stand pipe where the hose goes is overflowing and soaking the carpet under the wall….will this vac tip work? or should I try a snake or something? It went for a long time not overflowing…but just started up today…..The unit does run quite a bit though in these hot MS summers….any advice?

  47. Thanks for the tips on cleaning out the a/c drain pipe. Another issue I have is that the drain pipe runs through the house foundation into a PVC pipe and into my side yard about 1 foot away from my foundation. I live in South Texas, and am tired my having to walk around this mudpit to get to my back yard from outside. Will something like a hole filled with rocks work? If so, how wide, how long and how deep should it be? I have heard people talk about this before. One person mentioned a hole with a coffe can filled with rocks. Any help will be greatly appreciated. Please use only my nickname of “Jay” if you use this comment on your website.

  48. my dog got a hold of a plastic tube that was by the ac unit outside wonder what that would hook to i have a pvc condensation line that runs to drain in basement but what would that plastic tube run to in the basement look like the dog pulled it from somthing in basment because i can see the end of it.

  49. Hello,

    My A/C handler is in a hall closet on a concrete slab. It has a catch ben under it. For the past two months the bin has been over flowing out onto my floors. ABout every week I take the panel off and shop vac the bin. I can’t reach the access to the drain line because my hands are too big. The pipe is PVC. My question is can I use something like draino to clear any clogs?? Thank you.

  50. Judy and others: I had the same problem – no outside drain outlet and I tried everything. I finally tried the rubber bladder trick to send pressurized water through the drain. Worked like a charm. You can get them at your local home center for about $10.

  51. How do you unclog the primary drain that is tight-lined to the sink? My drain coming through the wall is dripping water so I guess my primary is clogged. Any help would be appreciated

  52. I found a pump (Mighty Pump at for cleaning and clearing out the main A/C drain line. It does not require any electric, it’s easy to use, and does not cost much. It took me about 30 seconds to clear my main line. I plan on using it every 3 months (including having my house sitter do it while I am away for the summer). It is the greatest tool I’ve bought. Danny check this pump out.

  53. My central A/C unit’s drain goes under the slab in my basement. I do not know where it drains to. I’ve never seen any signs of it draining around my foundation.

  54. Hey Kevin, If the A/C line runs under your basement floor, then it’s probably connected to the curtain drain that runs around the exterior perimeter of the foundation. A curtain drain is a network of perforated PVC pipe that carries groundwater away from the foundation.
    Of course, this is assuming your home has curtain drains, and the A/C line isn’t just draining directly into the soil below the basement.
    In any case, since you don’t have access to the exterior end of the line, I’d recommend blowing out the A/C drain line from inside. Start by cutting into the A/C’s drain line close to the air handler unit in the attic. Then attach a wet/dry vac, switch the hose to exhaust, and blow the line clear. Splice the cut pipe with a short section of clear rubber hose, and repeat at least twice a year.
    And it’s worth mentioning that there’s a product, called Mighty Pump, which is specifically designed for clearing A/C drain lines. The small, powerful pump can both vacuum out the line from the exterior, or blow it clear from inside. This is a great product. Check it out at: Thanks for writing.–Joe T.

  55. You’re very welcome, James. Hope this tips works for you and keeps you cool all summer long. Thanks for writing and good luck!–Joe T.

  56. Hi Lori, So glad to hear this simple trick worked for you. If you repeat it every few months, you’ll prevent a major clog from developing. Thanks for writing and good luck!–Joe T.

  57. THANK YOU THANK YOU THANK YOU!!! I just saved myself thousands of dollars worth of water damage! This trick worked so well!

  58. Hi Laquita, I’m so glad that this clog-clearing tip helped. It really is a “Simple Solution” but it works so well. Thanks for writing and keep watching/reading for more solutions to help you thoughout the year.–Joe T.

  59. Hi, I live in a condo on the bottom floor. Their is a pvc pipe that runs from the ac unit above me, then to my ac unit, then to a drain pan, then underground through my bedroom, and finally is released outside. This pipe appears to clog a lot. I’ve lived here sense the fall of 2003. And the drain pan that collects water then over flows into my unit. It happen in July 2004, July 2007, July 2009, and then I happen to spot the pan today and it was almost filled. My insurance company refused to pay for July 2009 because I had water damage in July 2007 in the same area. I never claimed July 2004 because I thought it was the water heater. Plus it was caught in time to only need the carpet replaced. I have used the dry vac from the outside and vacumed the water on the inside up. I pour color water down the drain to see if it comes out with color (and it doesn’t), but water is coming out (doesn’t seem to be as much as I put in). I do pour bleach down the pipe as my neighbors told me to do this to clear the lines. Last year we did the same and the maintance people came into my house while I was at work to use the hoze to clear the pipe with water. Does anyone else have any ideas as the pipe is clogging faster the longer I live here. Oh yeah, I had two other neighbors (who may not be reliable sources but were on the board) tell me there was an old oak tree that had to be chopped down as it was looking for water under the unit. I’ve been told I should get a plummer camera to see if it is my unit and if it than the only way to have my unit fixed is to sue. I been told the association only listens to lawyers and I can see this is true as they come into my unit as they desire (locks changed now) they ignore my letters, and they hang up on my when I’m asking for something (I’m not even cursing or yelling). I been told from unreliable source that their are people on the board who are getting paid off to keep their mouth shut. I know take everything from the source and never repete something unless you know it is true. That’s why I said unreliable source because it’s not been proven to me. Oh yeah and I was told by the unreliable source that we have a natural spring under the condo and the trees roots were growing into someones ac pipe… but they didn’t remember whose. I want to sell my unit as the place is terrible. They have so much money in reserve but they refuse to do any painting or fixing exterior doors. But the docs clearly state that I can’t paint my door or make any changes to the exterior. Sorry venting about how much I miss having the control of a house without the third party. Warning… know what your getting into when you buy a condo. I just have no idea what to do. I tried to find a lawyer years ago when I had mold because the association wouldn’t help with the cost of dry wall, but lawyers do not want to get involved with condos. And I’m broke. This condo was suppose to help me get through college, but it prevents me because of all the money I spend on it. HELP HELP HELP ME… I BEG FOR ANY AND ALL HELP!

  60. Wow, Melissa, what a nightmare. I’m so sorry for all your ongoing problems with the A/C drain. Wish I could come over and clear that clog for you. The good news is that you can probably clear it yourself, but first…
    Pouring bleach down the drain line can prevent clogs from forming, but doesn’t do much once the line is plugged up. Sounds like you’ve got a severe clog, so the wet/dry vacuum tip we showed might not work either. However, as I’ve mentioned to other viewers/readers, the Mighty Pump is the best tool for clearing stopped up drain lines (Check it out at: ). You can attach it to the outdoor end of the drain line, and pull out the plug with suction. Or, you can also blow out the plug from the other end of the drain line, near the air handler unit. However, sucking out the clog almost always works.
    Finally, if the oak tree’s roots, in their search for water, worked their way into the drain line, then you’ve got real trouble. No pump or bleach solution will help. Your only option is to hire a plumber or drain-clearing contractor (like Rotor-Rooter) to cut through the twisted mass of roots. However, I’m not sure they have root-cutting cables small enough to fit inside the small-diameter drain line. They just might, but I’m not sure.
    Again, sorry for all your troubles. Hope this info helps. Thanks for writing and good luck.–Joe T.

  61. Here is my problem, I got water dripping from my pvc line which comes from the drip pan. The drip pan is half full. There another line coming form the a/c the looks like it draines to the breather pipe in the wash room, is this the primary, is this the line that I should some who pour water and bleach thru, it looks like it doesn’t have that secondary line to do this. In your video you show how to suck out any blockage from the external pipe, but if its the one that pours into the breather than I won’t be able to do this.

  62. I have attempted to clean out my 1″ drain line from my ac. It is approximately 35 in lenght. I blew air through it and got out some rusty water, it seemed to be fee. I hooked it back up and with two hours it was backing up again. I hooked up a water hose and flushed it out, nothing but clean water came out. I turned on the hose with just a trickle, and a trickel came out. I opened it up and all came out. So I rehooked it and drilled a 1/16″ hole in top or pvc. to allow air. Didnt’ work, within thirty minutes it started coming out of the hole. When I opened up the joint there is water standing in the downstream part of the pipe. All grades are good, the unit is in the top of garage and it angles down to the floor and then runs level I guess, in the concrete floor. My next move is to re-route the line in the other direction to the outside wall. It will look somewhat bad but will be a lot shorter route.
    Before I do this do you have any sugguestings?

    Where the pipe comes to the outside it seems to go into wall then down too floor level and then goes approcimately 20 feet too ther vertical. I suppose this is some sort of trap. The house was new four years ago.

    Thanks for your help.

  63. ac unit has a pvc drain pipe into the basement floor…over the years i learned how to reomve the “ice cream cone” shaped drain and clean that so that the rising disk moves freely….this time that is not doing the trick –should i pour bleach into the floor hole?…thanks barb

  64. I have 2 HVAC systems in my attic – condensor units located outside. The evaporator coil units in the attic have primary drains (PVC) that connect to 2nd floor sinks under their U traps. The primary drains in the attic both have an uncapped vent about 6 inches higher than where they connect to the evaporator units so that I can easily pour bleach down them or flush them. Every year we have water in the overflow drip pans which drain via PVC pipes to the soffit above our back patio. Because these constantly drip on our patio I have always assumed that the primary drains must be clogged.

    Could this actually be an installation problem because the primary drain coming out of the evaporator unit (connects to bathroom sink) is at the SAME level as another PVC pipe coming out of the evaporator unit but draining into the overflow pan. The overflow pan then has a PVC pipe at the bottom draining to the soffit. Since both primary and secondary drains coming out of the evaporator unit are at the same level wouldn’t the water be equally divided between them due to basic physics? Could this be solved by putting a slight U riser in the PVC pipe going to the overflow pan so that the water would take the easier route down the primary drain?


  65. A couple days ago our upstairs AC stopped working. The next day, an AC technician came out and checked the attic. Said the drip pan was full which is what caused the AC to automatically shut off. Later that day another technician came out to drain the pan and check why it was filling up. He tried to get a clog out, but said there was none after he blew some pressurized air into the pipe. Either that or it was a small clog.

    Over Memorial Day wknd, the drip pan filled up again and the AC shut off. My husband used a shop vac to drain it to about 1/3 full on Monday night. It is now Wed night and the drip pan is 2/3 full.

    Does anyone have any idea as to why it is filling up so quickly? If it is not a clog, what else could it be? I read somewhere else something about frozen coils…

    From what I’ve read, the drip pan is kind of the AC unit’s back-up when the water isn’t draining properly.

    Any input is appreciated!!

  66. My PVC drain pipe from my central air unit has cracked at the threads going into the drain pan. Any tips on getting out the broken threads so i can put a new section back in. I temporary used hot glue to seal the crack but it isn’t working.
    Thank you

  67. I have a HVAC system that is not draining water. The furnace is in the basement and the drain tube coming from the system discharges to a floor drain. When I blow into the drain tube air moves freely so I can tell it is free of clogs. Is this a problem? If so, what is the fix?

  68. I was having dripping from the handler that is located in a small hallway closet. Called repairman and said the pan had a crack in it, replaced it. (I can’t see the drip pan) Today the system wasn’t cooling for a few hours and then began to. The temp went from 80 to 84 and remained there for about three hours. Finally began to cool again down to 77 and worked for about three hours. Now I notice it is not cooling.
    Please help…thank you!!!!

  69. I have two lines, a primary and secondary. My primary line drains out to my indoor plumbing. My secondary line runs from the drain pain out to the eave and drips outside. I noticed the secondary line is suddenly dripping a LOT of water, so I think my primary line is clogged.

    My problem is that my primary line does not run out from my drain pan sitting under the unit. It runs out from this big enclosure where the coils are (maybe another drain pan is inside there). Anyway, I may tackle getting inside of there but I want to make sure such a project is worth my while. Should I even try and mess with the primary line since it runs from the coil enclosure or should I just call a professional?

  70. Bernard, Eileen & anyone else living in a condo. Read this link and that should help you solve your condensation line clog problem. Seems like pressurized air is an effective solution when living in a condo. Personally, my tiny condo HVAC closet is so small & crowded with pipes that I’m not so sure I can get a wet/dry vac in to suck out the clog. I’m going to try the CO2 cartridges and clog-clearing gun to shoot pressurized air in the line to see if that works.
    Good luck.

  71. Hey Jim, Glad the wet/dry vac tip worked for your A/C clog. It’s especially impressive when you factor in the 30 ft. of horizontal piping. Good job, and thanks for writing.–Joe T.

  72. I have a split A/C system in a condo. The air handler condensate trap was full of water and no water was draining from the condensate drain line outside the condo (beside the condensing unit). I bought a wet/dry vac at Home Depot, brought it home, connected the vac hose to the drain line with duct tape, and ran the vac for 3 mins or so. A lot of green algae and water came out. I poured a small amount of bleach into the un-capped drain line in the air handler, then added about 2 cups of water, and vac’d the line again. All that water came out as evidenced by the odor of bleach. The line appears to be clear, but after 2 days, no water is coming out of the condensate drain. I live in South Florida, it is June, hot and humid, and water should be constantly dripping out of the condensate drain line, as it did before I got a new a/c system in November, 2009. The old system did not have a trap, the new one does. Could this difference make the unit not drain as it did before? Thanks, any help will be appreciated. Barbara

  73. I noticed some water damage on ceiling and discovered pan to be full of water. Called technician who blew out the primary drain line with compressed air and said should be ok. I emptied pan but next day checked and saw water building in pan again. Primary drain was not draining. It empties to drain under bathroom sink. Upon taking apart plumbing under sink, entire drain was pretty clogged, although sink would still drain. Tee from primary ac drain WAS completely clogged. Cleaned out plumbing and ac drain worked. The clog was actually caused by hair/gunk going down sink for 5 years that backed into tee. Also, the furst cleanout port on the primary drain before the p trap needed to have tape over it to ensure all if the water went out the primary drain and not the secondary. Hope my experience might help somebody wit similar problems.

  74. My primary drain does not have a cap to remove in order to pour in the bleach. Last year the line clogged and the HVAC repair man said just pour some bleach in the line on occasion and that will solve the problem. My question is where do I pour the bleach with the main drain not having a cap?

  75. Hello guys, I might have missed a posting about my problem/concern but I do have a slightly different issue. My hubby and I know about all of the techniques to clear the lines listed above. We used them 3 weeks ago. However, the a/c flood switch clicked off again today. The line was full but hubby didn’t find a visible clog when he cleared the line. There are only two elbows in the drip line and they appeared clear. Can anyone give us an idea why the line might have been blocked so soon? All input is appreciated. Thanks.

  76. I live in an older condo and have been experiencing some problems. Earlier this week, I had the compressor and the furnace replaced because it was very old, leaking, etc. A day later, I noticed that the A/C wasn’t working and called the company. A tech came out and said that the safety switch had been set off. He also said that I might have a clogged main drain and they might need to tear down part of the wall to find the problem. YIKES!!! I told him that I was currently unemployed and could not afford those types of repairs. Well, today I noticed the floor of the bathroom, where the furnace is located above, is all wet. I checked the drain pan and it is filled with water. Will the wet/dry vacuum solution help clear the main drain that the tech said might be the problem? I can’t afford any more repairs. Any advice will be greatly appreciated. Thanks.

  77. I live in Texas and have two AC units for my house. Both drip pans under units in the attic are bone dry. Directly below one of the units is my master bathroom and there is a black hose connecting to one of the sink drains. I assume this is the main drain for both ac units. Outside of the house by the two ac units there are two small pvc pipes sticking out of the hous with an elbow on them. I assume thes are the drain pan drain lines but not sure.

    Today I found water on my carpet close to my ,master bath in the area of the black hose. I shut off the main water supply to my house for and hour and drained all water lines. I could hear dripping in the wall.

    I went to attick and both drain pans were bone dry. I poured bleach adn water into both main drain lines. Went outside and didnt see any water coming out of the two small pipes by the units, or out of a pipe coming from the eves.

    I disconnected the black hose in the bathroom and blew air in it and heard water make some noise then a small amount of algae came out. I put everything back together and no longer heard the leak in the wall.

    My question is, is the black hose going to the sink drain the main drain for both attic units, and if so, why did water not fill the drain pans when it got clogged? Why did it run down in the walls?

  78. My AC drains from the main unit through PVC. It has a drain pan that has remained dry for 14 years. This year the drain pan is filling with water and causing a float / shutoff valve to actuate. The PVC is connected to the unit (and assembled) with PVC glue – is there any way to detach / clear the PVC without cutting it / replacing?



    • Hi Carole,
      You AC is probably dripping more than usual due to higher than average heat and humidity, but it’s not a good idea for it to drip on your brick ledge, since over time that may cause problems. I’d put an extension on it to direct the water on the ground away from your house.

  80. I have a Space Pak A/C system in my home. Last year the condensate drain clogged before and within the P-trap and need service. The service man told me there is P-trap with a self cleaner available but I can not seem to find one any where. Where can I purchase one of these? Are they worth the investment.

    J. Evans

  81. the drip pan under my heat pump inside of my downstairs closet was full I wet vac all the pipes which were filled with a mud like substance , what should I do water had seeped into my laundry room wetting the floor . help me please.

  82. I’m in Austin, TX. I noticed dripping from what searching on the web leads me to believe is called the backup condensation line. I checked in the attic and, sure enough, the pan is half full of water. Also, I think I managed to find the main drain — i.e. the one I’m assuming I need to clean out. So, the general advice seems to be, clean the main drain — warm water and bleach for minor blockage, snake and/or wet/dry vacuum for large blockage.

    Problem is, the inside of that “main” drain is dry. I don’t understand how that can be. Surely it should be completely backed up so that when condensate tries to get in there it can’t and so get’s diverted to the pan?

    I suppose I can always attempt to clean the main drain anyway, but is it worth the bother (i.e. is it actually blocked at all)? Can someone explain the leakage mechanism a bit more — specifically, how is it I have water in my overflow pan and coming out the overflow pipe, and yet the main drain is dry?


  83. @Steve (in Texas), I’m an utter newb here and trying to fix my own problem, but I think those pipes with elbows are the main drains, not overflows from the pans. I think the elbow is probably to make the occasional drip (regular drip, not overflow drip) inconspicuous.

    So when you poured bleach and water in, maybe you were pouring it into whatever leads to the bathroom? That would explain why you did not see anything coming out of the elbow pipes, and why you saw algae coming out of the bathroom black pipe. Possible?

    So here’s an alternative (highly speculative) theory. Your a/c is OK. Yes the drain pipe (the black one going to the master bath) is a bit blocked, but at the moment it’s not doesn’t matter because your main drain (the one with the elbow) is working fine (hence the pan being dry)

    In which case, something else, non-ac-related is the problem.

  84. I have almost the same situation as Jonathan… my pan in the attic is half full. BUT I have two pipes that run out of my house. One is down low and is by the AC unit OUTSIDE, this one is dry and not dripping at all. Then I have one that is up high, at an eve outside my home, this one has gone from dripping to a slow but steady stream. Is this the one that I am supposed to put a vacuum to and try to suck out a clog? Goodness, I can just see me standing on a ladder and attempting this…doesn’t look good. I’ve also heard of using a snake…do you do it there at the exit outside of the home or in the attic? In the attic it looks like there are a LOT of curves and bends and I’m not sure if a snake line will make that sort of bends and do me any good (and I really don’t want to damage anything…)
    HELP please…hopefully soon as I’m guessing I should try to take care of this quickly.

  85. Robin,

    Now bear in mind when I say the following that my system is still not right so I may well be clueless! But:

    No, I think the high-up one that’s dripping/slow-streaming is the “emergency” pipe and it’s doing what it’s supposed to. The question is, why. Usually no water should be getting to it (via the pan) because instead it should be coming out that other pipe.

    So, if I was you, I’d apply the suction to the other pipe — the low down one near the ac unit. The general theory is, it’s supposed to drip. If it blocks up, only then does the high up pipe need to kick into action.

    So I’d suggest:

    1. Apply suction to that lower pipe with a shop vac.
    If that works, it should end up with gunk and then water coming out. In that case:
    2. Then pour some water a cholorox down it from the top. That’s simply to discourage the blockage in future, which is largely algae.

    If the suction has no effect, try to decide it it’s because the blockage is too tough to move, or if it’s ‘cos you’re sucking on the wrong thing. For example, if when you suck does the vac begin to labor and change sound? If so, it may be sucking on a very tough blockage. You may then need either a snake or compressed gas (or get a plumber). OTOH, if the sucking seems fine but just isn’t bringing forth gunk and water … well then you’re where I am.

    Let us know what happens.

  86. There’s a good video on this problem here.

    Unfortunately I don’t get the gunk/water coming out as he does, and in fact I don’t think the pipe I have low down *is* my a/c pipe (although then what it is I’ve no idea).

  87. Great video and everything is clear and makes sense. However is it possible that there is no outdoor drain line? I checked the back of my house where the air conditioning connects and there is NOTHING that looks like the drain in the video. HELP! air conditioner is leaking like crazy. Thanks in advance!

    • Hi Rich,
      Every air conditioner I know of removes humidity from the air and has to dispose of the excess water somewhere. It’s possible that your AC drain line may run into a drain in the plumbing of your house or a drain used by a basement sump pump.

  88. Yes, Rich, as you’ve discovered, not every A/C condensate line drains to the outdoors. Sometimes it’s connected to a buried drain line. If you can’t locate the end of the line, you’ll have to cut into it near the air handler in the attic or utility closet, and blow (not suck) out the clog. You can try a wet/dry vac, set to “blow” but the Mighty Pump would likely be a better option. Check it out at Good luck and thanks for writing.–Joe T.

  89. Thanks. Perhaps I may have to try to get to my attic. I guess I’m having trouble identifying what I’m looking for to follow (whether it be to the ground, the attic, or to plumbing). Besides electrical, there is a connection wrapped in black, rubbery insulation (i’m assuming that is the “coolant” line… along with this there is a metal/coppery line that attaches to the bottom of the air conditioning unit itself. Is it possible that this is the drain line? it looks very different from what is in the video. If that metal line is not the AC drain, how can I identify it?

  90. We just moved into a new house in March and our AC unit outside has a drain line that drains into the yard next to the unit. The area where it drains is extremely soggy and muddy. We can’t even mow that area. Is it normal for that much moisture to be discharged? Is there something we can do to prevent it from making a swampy spot in our yard?

  91. Well, Tammy, the amount of moisture being released by your A/C might seem high, but it’ll likely vary from one summer to the next. However, you shouldn’t have to live with a soggy spot. Depending on where the end of the line is located, you could bury it and extend it to the edge of the property, set down a splash block or gravel bed to disperse the discharge, or even put in a small dry well. Again, next year this might not be a problem, but solving it now will eliminate the soggy spot forever. I’d also suggest that you contact a local A/C contractor and ask his/her advice. I’m sure this isn’t an unheard of problem in your area. Be sure to say that you’re looking for a low-tech, DIY solution to this problem. Most contractors are happy to dispense at least a little free advice. Good luck!–Joe T.

  92. I have a 7 year old Trane heat pump. Condensation water has suddenly began to run out of a small square port located next to the PVC drain outlet and just above the filter cover. How do I remedy the problem?

  93. Thanks so much, your trick worked wonders! We have a system that shuts off if the water isn’t draining, so it’s been a hot couple of days here in So. Florida. We called a technician, who said that he cleared the line, but within 2 weeks, it was backing up again. We kept trying to wet/dry blow and suck out the clog from inside the house, but it would only fix the problem for 30 minutes and then fill up again. After we found your video we decided to go hunting outside for the outlet. We live in a condo, so it was a little tricky to find ours. Once we did, we had to vacuum the line for a couple of minutes, and then I heard some rumbling from the pipe, and a bunch of “goo” came out. Now it’s working great, our condo doesn’t feel like a sauna anymore, and we saved $200 since we don’t need to call a technician out again! Thanks!!!

  94. Hi Michelle, I’m so glad to hear that your persistence paid off, and that our tip worked! Just remember to vacuum out the line every three or four months to keep it draining properly. Thanks for writing and good luck!–Joe T.

  95. I have read how to try to unclog a pipe, but mine pipe seems different from everyone elses. I have a older home and in my laundry room is my AC unit…the ac unit sits ontop of a wooden box that has concreate underneath it.It does have a pvc pipe running from the unit through my outside wall down to the carport and off the carport to the ground. t seems that these PVC parts are very glued together. I have tried several attempts of taking them apart with no sucess. I do not know how or where to pour the bleach since I can not get the PVC pieces apart. Could I just use the wet dry vac and see if it works? Also I notice a very nasty smell coming from my laundry room and I took my filter out which leads to the box under the ac unit and it is filled with water maybe two inches. Help, It is leaking from the box and into my laundry room. This can’t be good. Any pointers on how or what is wrong with it?

  96. PLEASE HELP ME! My ac blower works, air comes from my vent, but it is very low and not cold. I dont have a part of my airconditioner unit inside. Im pretty sure I have a large package unit outside. When I look at it I dont even see a place to take a cover off or anything. There is a small copper end sticking out with a small amount of water coming out. Is this the drain? Shoud alot be coming out? Again please help me any way possible! Thanks

    • Hi Mom of 3 Kids,
      A clogged AC drain line can cause water to back up inside your unit, but it doesn’t sound like that’s your problem. It could be any number of things, and may be as simple as having the coolant recharged in your unit. Your best bet is to have a licensed HVAC pro take a look at it.

  97. Danny,

    My drain was clogged and after following the pipe I discovered that it is connected to a rubber hose that goes underground. It is this rubber hose which is clogged. My question is 1. Where does this hose go? 2. Is this hose really necessary. Is there any harm in just allowing the water to drip by the house? FYI — I live in Florida, and so I have very sandy soild.

    Thanks for your feedback!


  98. It has been an unusually hot summer this year in PA and my condensate drain is giving me problems. The pvc pipe drains into the floor/foundation in the basement. As instructed by the HVAC tech. in spring I poured 1C of bleach into the hole into the basement floor drain but since early July the drain is clogging and water is flowing up out of the drain openingevery couple of days. I have also been using CLR and trying to unplug drain by plunging when I used the wet vac only a little water came up but mostly rocks. Thanks for any advice to my situation.

  99. I have learned alot. In Virginia the temps have been very high this summer – so my AC in the attic runs all the time.
    The “drip pan” is half full, but is dripping slowly to the outside – it appears the line is open. I don’t think I need the bleach and dry vac at present. To be on the safe side – I will remove some of the water by hand. ( IF I am wrong – please let me know!)
    Excllent information

    Thanks Bob

    • Hi Bob,
      If your condensation line is draining properly, the pan should stay empty, not half full. I would definitely use a wet/dry vac to suck it out now, followed by pouring bleach in the line, before it clogs completely and the water backs up in your house. An ounce of prevention . . . .

  100. Hi,

    We are having a problem with a leak from our kitchen ceiling which is under the air handler unit on the second floor of our town home. Two visits from an Air Conditioning company within about 7-10 days did not resolve the problem.

    On the first visit the guy said the lines needed to be cleared and that was definitely the problem. After he left it seemed alright for about five days and then started leaking again. Called the same place and they sent a different guy out who cleaned the evaporator fins on the air handler unit upstairs which seems like it’s leaking quite a bit. However, he said that he thought the drain pan must be leaking but that there was no way to access it so the only way to fix the problem would be to replace the entire air handler unit. Unfortunately, we are in dire financial straits right now and cannot afford to do that. He also said it was an old unit that he wasn’t even sure they could get anymore!

    After he left, the leaking stopped for about another five days again. At this time I saw that the filter had become very dirty so I replaced it. The leak seemed to stop yet again for about five days! I don’t understand why the leak would stop after each of these events if the pan has a leak in it. Also, water comes out of the drain outside.

    We have never had a technician try to access the attic yet. It’s in an awkward place above the washer dryer and a shelf is in the way a little, but still, shouldn’t they have at least looked in the attic to see what access was available, and at least have tried to look at the air handler other than from a panel and filter access at the top of the stairs facing into the living room? Unfortunately, I have health problems and will need a hernia operation soon, so I can’t attempt to get in the attic and take a look myself. Any help or advice would be GREATLY appreciated.

  101. Hi ….!
    Thank you very much for your advice. I works even without the bleach. I used wet/dry vac it worked perfectly.
    You SAVED me 100$ at least and a lot of annoying time waiting for the technician . thank you again .
    with much respect

  102. Hi, Our central air unit is dripping tons of water inside at the little pump area. We have cleaned the hose that leads to outdoors, but it didn’t help, yet not much at all is dripping outdoors. The drip pan is overflowing quickly, like within minutes after emptying by hand. It all pours down to our floor into a cooler at the moment. I’m not sure if the pan can clog in another location. The pump turns on every few minutes because we hear it running… though we’re not if its doing anything. Is there something else I can try myself before calling for help? I don’t have repair money at this time. Thanks for any help. Jim

  103. My a/c unit just started giving me trouble lately. I have alot of water dripping from the underside of my indoor unit. My drain is a pvc pipe that just drops into a 2in pipe that runs in the foundation to the rear of the house. The bigger pipe is clear but I think im supposed to have a vent on my drain line but it just comes out of the unit and down to the other pipe. Need help, thanks

  104. I don’t have a shop vac, it’s after hours and my unit was not cooling. It was HOT in here! I searched the net and read your tip, and decided to follow the drain pipe from the unit (it’s in the hallway) and found it connected to my bathroom sink (not outdoors which was a very good thing for me). I put a bucket under the sink, loosened the pipe (pvc pipes – I was able to loosen by hand). As soon as I loosened the lower elbow, water rushed out and I found a hair clog (held together by makeup residue, facial creams, etc.) I thoroughly cleared the drain, cleaned the lower elbow with some hot water, Windex and a rag, removed and cleaned the upper elbow the same way and put it all back together. Then I added some bleach to the drain pipe next to the air unit through the air vent and poured some down the master bath drain (for good measure). The temp dropped from 86 to 80 in less than 30 minutes. I’m a single mom with a kid in college. I used no tools and this took about 20 minutes and cost me 2 pairs of disposable gloves and about 50 cent’s worth of bleach. I’ll get something at Home Depot tomorrow for preventative maintenance. I will also share all this with my neighbors in my subdivision as we all have the same units and are all experiencing similar issues. Thank you for sharing!

  105. I recently started noticing water dripping, well more like running, from a pipe I’ve never seen it drip from before. So I started doing some research and learned that it was the back up drain line for my Air Conditioner condensate. I read different methods of clearing the line. First, I tried to access the clean out on the primary drain pipe to pour some bleach down it. Unfortunately for me, who ever installed the AC in my house didn’t put a clean out on it. So I tried another method, the shopvac. This was ineffective. So, my brother is a plumber and I thought I’d have him look at it and maybe put a cleanout on it for me so I could pour some bleach down the drain. When he cut the pipe to do so, we realized the drain pipe wasn’t even clogged. It seems to be clogged before the condensate p-trap. Like maybe in the unit itself. I’ve tried to see what I can do to fix this and I’m not finding anything online. Also, I don’t know if this helps, but my wife and I just discovered that there is water leaking from only one of the vents (our vents are in our ceiling because we live on a slab). Is there anything I can try to do before I pay someone for a service call?? Thank you for your time!

  106. When walking around my house yesterday I noticed a puddle of water next to my house. While investigating, I saw a white pipe coming from the wall. I assume this is the A/C drain line. I’ve never noticed it before because it is directly behind a bush and there has never been a puddle build up there. What could be causing this puddle to form next to the house like that and do you think this is a DIY fix.
    Thank you for your help!

  107. I just had my drain line unclogged and the tech placed a new drain fitting t-pipe on the drain line above the unit and closed off the old one. Today I was going up in the attic to pour a cup of bleach down the new drain to prevent future clogs as the tech suggested. I was very unsuccessful due to cool air blowing out thepipe. Is this supposed to have air blowing out it? The bleach just bubbled up and wouldn’t go down the pipe. Do I need to call the tech back out? Thanks for any advice!

    • Hi Susie,
      Be sure the AC unit isn’t running when you pour the bleach in the drain line to prevent any air from coming up through it. If you don’t have one already, put a cap on the drain line access port when you’re not cleaning it (caps for various types and sizes of pipe are available in the plumbing department of your home center or at a plumbing supply store). Good luck with your project!

  108. Hi Danny,

    I have noticed a mildew smell in the house over the last couple of days so I went into the attic and noticed the drain pan had standing water in it, so I would assume we have a clogged line. While up there I noticed that there was a bit of mold around the duct work that connects to the unit in the attic and on one of the vents that leads into the house. Is this what is causing the smell? Should I try the two steps you show in your video…the wet/dry vac step and the bleach? Do you think we need to have the ducts cleaned out, in case there is mold? Thanks for your help!

  109. My AC drains from the main unit through PVC. It has a drain pan that has remained dry for 10 years. This year the drain pan is filling with water and causing rust to form on the outside of my vinyl siding since my unit is in the attic. What is this cause and what is the solution.


  110. George from Austin, TX said: “Have a friend/spouse go to the AC system and plug up the bypass line with their hand (i used a 1/2 pvc cap i had lying around). This will give you a more solid suction and pull out the gunk.”

    I just wanted to say thanks, George. That was exactly what I needed. I had the wet-dry vac working and working, and I was still getting water built up in the drain pan. Once I found and plugged the bypass line on the unit in the house, I got the clog out with the vacuum. I wasn’t sure which line was the bypass line, so I left the vacuum running on the drain line and hurried back to the unit in the house and listened until I could hear the air moving through a line. It had two outlets, each of which was too big to seal with my thumb, so I used a couple of small rubber balls, sitting them on top of the two outlets on the bypass line to plug them up. Then I went back outside and worked the wet-vac, and pretty soon I was hearing a “clomp-clomp” sound, and water was gushing into my wet-vac.

    I think this trick saved me the $70 I would have had to spend otherwise on the “Mighty Pump” thingy.

    Thanks George – very helpful.

  111. Decent trick but be careful of blowback or vapor coming from the wet/dry vac exhaust. I’d hate to see any readers get an eye full of bleach. Make sure that you stand away from the wet/dry vac exhaust…

  112. I have a new Carrier AC (bought new home 2 years ago) with a Safe T Switch and it stopped last night. The Carrier website said that the condensation line should be cleaned. I cleaned the filter. I checked the coils, its not frozen. How do I clean the condensation line or turn the unit back on if it has anything to do with the Safe T Switch? Any suggestions? Thank you.

  113. When my HVAC was installed, the primary and secondary drain lines don’t drain water away from the unit since they are not installed lower than the unit. Basically, the pipes run uphill and the water can’t flow out. Now, one is leaking down into my attic and soaking sheetrock. Should I lify my HVAC unit up a few inches hoping to not crack or break the ducts that attach to it?

    • Hi Liz,
      I would turn the AC unit off first and wait until it stops running, then pour the bleach into the AC drain line. After allowing the bleach to work for 10-20 minutes, you can pour tap water in to rinse it out (it doesn’t need to be hot), or the condensation from the AC unit will rinse the bleach out over time. You can find out more in our other video on How to Clean Out an Ac Condensation Line. Good luck with your project!

  114. Lots of water drips under my AC unit. When it first started I didn’t know what to do about it so I just put buckets under there and would empty them every day. This spring I decided not to use it at all until I could have it fixed because I’m worried about mold possibly getting started. I had a guy come out and look at it and all he did was blow out the drain line and charge me 60 bucks to do so. I used the AC the next day and noticed that it is still leaking underneath. I looked and felt underneath and found that there is a lot of thick rusty gunk in the pan and the pan was full of rusty stagnant water. My unit has only been used four summers, should it be so rusted already? I took off the side panel and looked in there to see the other side of the drain pan, and it was sitting full of extremely rusty water and the coils and everything was very rusty. Should that water just be sitting stagnant? I thought it was all supposed to drain? I looked at my drain line and noticed that the line seems to go slightly uphill from the drain hole. Shouldn’t it slope downward since its a gravity drain? It seems that the pan is having to get so full that it runs over before the water will overcome gravity and some of it will drain out.

    • Hi Savannah,
      You are correct, since the AC drain works by gravity, the pan needs to be level (or slope toward the drain) and the drain line needs to go downhill from the drain pan. It’s not unusual for the pan to have a little water in it while the AC is working, but it should drain out freely.
      Good luck with your project!

  115. Greetings!
    Thank you for being so forthcoming about your knowledge! I have a fairly new HVAC unit and the installers told me to pour a cup of vinegar into the overflow pipe (which is inside the house) once a month and to put a whole gallon of water with some vinegar into the air handler during summer-time.
    Well, this seems kind of excessive to me, but he seemed confident. “Trust us! If you don’t do it, we’ll be able to tell!” he said.
    When I asked him what kind of vinegar, he said “any kind”. My questions: is apple cider vinegar OK? It seems to work for everything else around the house! And is a gallon too much water to add?
    Finally, do I have to turn off the unit to pour this mixture in?
    Thanks and God bless, Ben!

  116. My drain pipe runs from the central unit on of the closet floor into the garage floor troft gravel just has always soaked up the water. It is plugged and my closet floor and part of bedroom is getting really wet I mean soaking wet carpet. I tried to run a hanger up the rubber end thagt connects to the copper. I can not get to unplug? Could I shoot some air in the line? Thanks for your help. Liz

  117. Thank you so much for the help. This happened to us and we didn’t know why. I watched your video and immediately went out with the wet dry vac and viola it is not leaking over anymore. I can’t thank you enough. 🙂

  118. Hi, we are having a problem with our heat pump and are wondering if our dog could actually be causing it. We have noticed for the past several weeks that the dog comes in muddy even when there is no mud in the yard, and have narrowed it down to her laying in the drainage next to the outdoor unit.

    About a week ago we put up some barriers so that she can’t get into most of the drainage, and we made sure not to block the tube where the water comes out. The dog is still somehow getting muddy from it and the only place there would even be room for her to lay would be right in front of the tube.

    Well today we noticed a little bit of water in the floor beside the INDOOR unit. My husband opened the front and everything looked fine, nothing was frozen over or leaking inside that he could see. We dried the floor and moved everything out of the way so we can see if it happens again.

    We are just wondering if the dog could somehow be blocking the drainage outside and causing it to get backed up. I guess my real question is if an outdoor blockage could cause an indoor leak or if it’s more likely to be something more serious happening to the indoor unit. If the indoor water leak happens again we will definitely call someone to look at it though. Thanks!

  119. We had our air conditioning unit installed about 5 years ago, but we did not know that he didn’t connect a drain line. The water has been draining under our house every summer, we have had mold issues, and my wood floor has warped. We finally found out why. We aren’t exactly sure what we need to do. I know we didn’t have this issue before with our other unit, which was about 20 years old. We need to know who we need to call for this issue, and do you think there is a line that goes somewhere that he did not hook up? Please, I need some advice.

  120. my air conditioner is running but not putting out cold enough air, I checked the pvc pipe that the condensation should run out of but it is dry however there is not any leaking of water anywhere around the unit, I used a wet/dry vac to clean the pipe in case it was blocked, but still nothing. Any suggestions?

  121. a/c drain — draining to much out side my yard and causing my grass to die and buling moss and mildew what should i do ? need help/ advice. thanks..

  122. I want to say Thank You, Thank You, Thank You! Your advice to use the Shop-vac to unclog the drainage worked like a champ. The A/C unit stopped working during some of hottest days in July (2011) and all due to the excess of water accumulated on the drain pan. There was not enough water to drain on through the back-up pipe, but enough to activate the sensor. After flushing all the dirt with the Shop-vac, the A/C unit continued working normally. We feared that it would be yet another costly repair and thanks to your advice I got the A/C up and running in no time for just 30 bucks! Thanks again.

  123. A air conditioner repair person came to my house and the air handler in my attic has a trap on it. He drilled a hole to clean out the trap, however, he left the hole open at the top of the trap. Should I be concerned that water could come out of the home from the top of the trap?

  124. I have a problem with water dripping from the split AC every time it rains. The water drips from the pipe in the wall that connects to the indoor unit. This is the case with more than one AC in the house.

  125. I’ve tried the bleach, and shop vac methods, but still cannot get the main drain unclogged. There is a secondary drain that drains into a bathtub, and I can shop vac that one, but the condensate pan still overflows if I don’t suck out the secondary drain at least 3 times a day. The main drain is 3/4 PVC. and runs approximately 40′ laterally, then 10′ up, and then 2′ laterally. Has anyone ever used a snake to clean one of these things?


  126. I manage a large condo in Boca Raton, we had one unit where its AC line kept blocking but no one else. From the roof I used a pipe camera and found that that section of AC line was blocked with algae. We cleaned the line with a pipe snake from the roof and will run some water mixed with Clorox and some white vinegar in it.

    This should fix the problem for some time to come but we will occasionally put the mixture down to keep it clean.

  127. Turns out the leak was from the roof, but I still have the problem with the main A/C drain. I took a 100psi air compressor, and blew it through the drain from the out let side, and you can hear the air whooshing through. So that must mean the line is clear enough to allow water to flow. I’ve either got a disconnect between the drain pan, and the pipe, or the drain pan is tilted the wrong way. Gonna have to cut out some dry wall to take a look.


  128. Hi ,try this wet vac attatchment which fits air tight on wet vac hose and condensate line pipe and creates a very powerful vacuum on youtube also .good luck!

  129. Jack:

    I did not get it solved. I did find out that the dripping was from a roof leak, and I fixed that, but the main A/C drain is still a mystery. I took a 100 psi air compressor, and blew it through the line. You can hear air whooshing at the air intake so I’m assuming the line is clear, but still no water comes out. I think either the line is disconnected from the drip pan, or the pan is tilted the wrong way because the overflow line at the other side of the drip pan does drip water, and when I put a wet vac on it it sucks quite a bit of water out. I’m just going to have to bite the bullet, and cut out the drywall to see whats up. Will keep you advised



  130. My AC drips water from the air intake located in the ceiling and there is no water building up in the drain pan. This is highly confusing. Any idea what may be going on?

  131. I found out I have a considerable armount of water under my home. The condensation wasn’t draining properly therefore it caused floors to warp and also structural damage.

    I need to find out an approx number of gallons that were produced per day from the condensation. Temps of 90 to 107 outside. My AC at 65. Is there a calculator or formula for this? By the way, it caused a high amount of humidity in my home. Probably caused a vicious cycle.

  132. hello-


    my AC unit was installed 2 yrs ago. i started having water drain problems the first summer just a few months after it was installed, when the AC was being used for the first time full-time. unfortunately my contractor moved to another state, so i was left without warranty & without anyone i could trust to call & do the job they get paid to do.

    also unfortunately, maybe because they see a woman who has no real knowledge of how to do this that could tell if they didnt do it right; and has no option but to trust whoever she hires & pray to not be taken advantage of by charging unreasonable amounts of money and not really fixing it. (how could i know if they actually fixed it or not before they leave? or how could i even prove that they didnt do the job right the first time so they dont charge me again?) it wasnt just one time. i’ve hired the services of HVAC “professionals”. these are companies i picked from the yellow pages since i couldnt find anyone with recommendations from someone i trusted. twice last year & already once this yr, so far, i’ve had the same experience with all three! not only i’ve paid a fortune for it not being done, but also i still have the problem. i live in a condo and the unit below mine is being affected as well, greatly i might add.

    i NEED to have this REALLY fixed once & for all. i’ve had too many problems as a consequence of this ongoing issue. i havent been able to remove the bucket i put there for the water once the drain pan gets full. i just have to make sure i empty it every few hrs so it doesnt overflow and cause another flood or worse, to drain to the unit below mine. this is not a solution i can even use anymore. the AC is getting all rusted because the water level never goes down on the drain pan.

    i cant know for sure it’s clogged but it’s certainly what looks like. the water doesnt drain it just stays in the tray & leaks while the AC is on & try is full. the contractors i hired before they’ve said it was clogged but how can it be that it gets clogged after just a few weeks of use? unless they just didnt do it right.

    i read all the input from everyone above and the sites you recommended to others, but i didnt find a solution that works for me to unclog the drain pipe, where ever the clog might be.

    my AC drains from the main unit to the drain pan through PVC. i cannot unhook the PVC as it’s is directly connected to the unit’s water drain tray & permanently glued. i have no idea where the water goes ends up going either. so i cannot suck anything at that end. is there any way i can on my own detach|access|clear the PVC without cutting it or having to hire someone to replace it? i honestly can’t afford to continue being charged for nothing. they took it all and now i cant pay for any more “repairs”.

    i havent been able to pour the bleach because the space available in the drain pan to access the hole to the PVC drain is too small for me to do as you suggest. nothing fits. how should i pour the bleach if i cant put it directly in the PVC drain? should i pour it on the tray high enough to reach the PVC drain hole and see if that works? i’d have to fill the tray at least half way but not all the bleach will reach the hole, so it wont drain. it would eventually leak when the tray fills up again.

    could you PLEASE PLEASE PLEASE HELP ME so i can do this on my own?

  133. This was tremendously helpful. Unfortunately the installer didn’t install the tap for the bleach so I had to cut the pipe to twist it off because I wasn’t sure the wetdry got the clog (it didn’t). It seemed to have a lot of white calcium type sediment. I might also suggest trying a plumbers snake. Draining into a bucket for now, will rework the PVC with the tap tomorrow. Thank you. Will bookmark for future.

  134. My son really needs your help. I beleive the A/c value that is drippping right outside his bedroom window, may have caused fugus under the building and causing him and I have major respiratory issues. I see the valve dripping and making the area very damp, and wonder how I can effectively move that drain so that it drips away from the house. I also need to know how to dry out that area so I can get ride of the fungus under the house right under his room. Please Please please help. He is feeling sooo bad and I have him on tons of medicine just to get him thru this, but I need to fix the source of the problem so he can off this medication, he is a major soccer player and recently got cut from the school team because he couldn’t perform, when he is an awsome player and sought out by travel teams in the area. He was heartbroken and I promised him that I would get this problem fixed, i just don[‘t how. Please advise. I have taken pictures of the set up and can forward if that will help. Thank you so mch for your help. I look forward to hearing from you SOOOOOOn

  135. Ihave two units in the attic,one drains good ,no water in pan and the other has water in pan .I followed every direction i was told to do, like pour bleach down the line , blew the line with shop vac.Both drains are connected to bath room sinks up stairs. I checked the sink that connects to the one that is clogged, and feels like the air coming thru, but is still condensating on secondary line on the outside, what do i do next.

  136. we have central a/c unit in a closet and pipe drains outside we have blown, sucked and poured bleach and still it leaked then we decided ok is drip pan tilted so we shimmed it up just a bit. All was great for about 3 days now its leaking again. How can we check to see if drip pan is cracked or if it has a hole in it, do we have to remove the A coil? With this going on again we checked and there is still water dripping out the outside pipe too.

  137. Thanks for a good video.

    My drain was plugged. My drain from the AC feeds into my internal plumbing. I disconnect it, hooked up my vac, worked at it for a few minutes — and then got it to drain completely.

    Good stuff!

  138. Does it matter if the ac unit is on or off when trying to use the wet vac to clear that drain pipe?? Does it make a difference? I’ve tried several times, and cannot seem to clear the pipe – still water in the drain pan.. ?

  139. New home owner found myself facing a clog out of reach of my drain snake. Great solution and so much cleaner and easier. Thanks!!!!!!!

  140. Thank you so much!
    After watching your video I cleared my pvc line in a total of 10 minutes!
    This is thanks from a 61 year old homemaker.
    You saved me a service call. I knew my hot pink shop vac would come in handy!

  141. Don’t use bleach. Bleach will damage copper, plastic and pvc. It will also caused the joint to leak by eating the glue away.

    People say use it when the ac is on in the summer because the water is washing it right out. However that’s not the case when it’s clogged or when there is little humidity the bleach can sit in there.

    Why use something that will eat the pipes and glue. Use white vinegar. It works just as good and does not damage the pipes.

  142. Ok attic people…. pay attention, this may be part of your problem with this not solving your drain issue.
    Check your air handler (box in the attic that looks like a furnace) and you will notice the coil is before the fan…….. it is sucking air thru the coil instead of pushing it. It should have a tee with no vent. if it doesn’t, install one. if you want a vent put it AFTER the trap. a trap is an elbow down then across and elbow back up to trap water in it.
    The problem is……… when your air filter gets a little dirty, the unit fan will be sucking air thru the vent or the drain pipe to go thru the unit and no water will come out with the unit on. it sucks it back in until it overfills the drain pan.

  143. We had a clog and I wet vaced it out but now very little water comes out of the copper line. We have to leave the sensor out of the pipe because it fills with water and turns the unit off. My question is this we have a pump does that pump need to be primed in some way to get that good water flow back it almost seems like there is air in the line now? Thank you Kaye

  144. OK I’m bit confused if anyone can help. My drip line was clogged and i found it and cleared the line. I never touched any electrical and my unit will not kick on now. I’ve checked all the breaker and the switch line has no water. Does anyone have a suggestion.


  145. Nathan, I’m sure this is too late, but; check and see if there’s a safety switch that’s triggered on the pan. Lots of units have that built in for when the drain pan gets close to overflow to prevent water in the House

  146. Hi, we have a problem with a semi clogged line. Problem is, to clear it out we have to find the end line which we cannot find. Literally the drain is come out near the unit but this house was built sort of odd and the line goes away from the unit out the other side where it’s under a porch but we still cannot find that line anywhere. We’ve checked the unit up and down for any signs of water but found none, followed the line to it’s possible location to find any signs of water leaking out but still nothing. The owners swore that it does not lead to the septic.


  148. I was so happy to read that you can prevent AC clogs so easily. My AC recently broke; leaving our house sweltering. I will be sure to get my AC serviced and will take preventative measures for next time so I can keep my house nice and cool.

  149. So recently the blower to my hvac has quit working. So I ordered another switch board and replaced it. It then started working again. Well it’s been about a week and I went back under house to grab a tool that I left. That is when I noticed water. I opened the hvac to see that everything in there was covered in moisture and water. All the electronics. And the tray behind blower is full of water. Also noticed that above the blower the installation is sagging and the blower is about to suck it right in. So I immediately shut it off. Can anyone guide me to what might be causing all this water. Thanks

    • Hi, Yvette,
      Danny says, “Most condensation lines drip right on the ground and it’s good in that you can see that the condenser line is working properly.
      “If it’s concealed in a sewer pipe or drain pipe, you can’t and won’t know if it’s working properly. If it’s not sealed up, there’s really no problem in it leaking into the drain line.
      Thanks for your question.”

  150. Is it possible to attach a drain line for an A/C to a drain line in your crawl space instead of outside, which creates a muddy mess

    • Hi, Paul,
      We don’t recommend draining into the crawlspace as this area needs to be dry and well ventilated.
      Draining in this area could promote standing water situations and fungus growth.
      Thanks for your question!

  151. I have condensation on my windows from the inside. Humidity levels are high 70 to 80% inside the house. Ehat do uou think is thr problem? I did blow the AC drain line and pour bleach down the line. Still have humidity problem.

  152. The water drain line for one of our AC units recently burst. The line runs from the attic to the lower level of our three story townhome. The break was in the ceiling in the ground floor level bedroom. Instead of opening up the walls and ceiling on all three levels of the house, the AC company has recommended that a new drain line be run from the attic level to the exterior of the house and then outside along the gutter downspout. At the ground level the new drain would be attached to the existing exterior portion of the existing drain line. According to the AC company, this fix does meet city/county codes.

    Can anyone confirm for me that is a viable solution and that it is ok to run a AC drain line on the exterior of a house? Thanks so much.


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