How To Fix a Noisy Air Conditioner

A noisy air conditioner can be more than just an annoyance—it’s often a sign that something’s wrong. Whether you hear a banging, screeching, or rattling sound, these noises can all point to specific issues with your air conditioner.

In some cases, fixing a noisy air conditioner is a simple DIY job. However, if you’re looking for one of the best HVAC companies to take care of it for you, use the form below to get an estimate from a professional near you.

Common Causes of Air Conditioner Noise

Air conditioners make plenty of noise when they’re operating normally, but unusual or excessive sounds are often signs of a problem. Before you fix your AC issue, you need to identify the cause. Here are some of the most frequent culprits behind a noisy AC unit:

Malfunctioning Parts

Several parts can malfunction and cause noise in an air conditioning system. Some of the top culprits are:

• Run capacitor: A failing capacitor can result in motor issues, causing buzzing or humming noises.
• Fan motor: When the fan motor begins to fail, it may produce grinding or squealing noises. If this happens, you may need to add lubricant.
• Bent fan blades: Blades that are bent or misshapen can cause a clattering noise as they turn.
• Air compressor: A failing compressor can make a rattling or banging sound.
• Blower: Blower issues typically manifest as a loud humming noise. If this happens, you’ll likely need to hire an HVAC professional.

Maintenance Issues

If you don’t keep up with AC maintenance, it can lead to noise problems. Some of the most common causes are:

• Clogged, dirty, or missing air filters: When the filter is dirty or missing, the HVAC system compensates by working harder, leading to louder noises.
• Dirty condenser coils: Buildup on condenser coils can cause the system to overwork, resulting in excessive noise.
• Loose screws or parts: Any loose fittings can vibrate or rattle, making a constant noise as the system runs.

Refrigerant Problems

Issues with the refrigerant can also cause your AC unit to make unwanted noises. Refrigerant leaks make a small hissing noise, while low refrigerant levels can cause a gurgling sound. You may be able to add refrigerant as a DIY project, but you’ll probably need an HVAC expert to patch any leaks for you.

Related: Why is My AC Making a Loud Noise When Starting or Shutting Off?

Identifying Air Conditioner Sounds

Different noises can indicate different problems with your air conditioning unit. If you know what to listen for, you can pinpoint exactly where the problem may be.

Squeaking or Squealing Noise

A high-pitched squealing or squeaking sound often points to problems with the fan or motor. This could be due to a failing run capacitor, an obstruction preventing the fan from turning, or a bent fan blade.

If you suspect these issues, shut your AC off and call an HVAC professional immediately. If you continue to run your AC, you may cause more damage to your system.

Buzzing and Rattling

These sounds typically indicate loose parts or electrical issues. The constant vibration of the AC running can loosen screws and bolts, which can make a rattling noise. Most homeowners can tighten loose screws and bolts themselves.

However, problems with capacitors, contactors, and other electrical parts can also produce buzzing sounds. If the noise is caused by one of these issues, schedule an inspection with a qualified technician.

Banging Noise

A loud banging or slamming sound, especially when the system shuts off, may be caused by airflow and pressure issues in the ductwork. Blocked or inadequate ductwork can cause pressure fluctuations, which can make a banging noise. Likewise, loose air cleaners or air filters may fall and hit the return grill, causing a banging noise.

If you have an outdoor AC unit, debris can also cause a banging noise. To fix this, clear any obstructions and make sure there’s no debris inside the unit.

Pulsating Sounds

Rhythmic pulsating, thumping, or humming noises often point to compressor issues like a failing compressor or internal compressor component problems. These issues are typically more complex and require inspection from an HVAC professional.

Bubbling Sounds

Gurgling or bubbling noises may indicate standing water in the condensate drip pan or a clogged drain line causing water backup. Drainage issues can lead to mold and system damage, so try clearing the drain line to eliminate any buildup. If that doesn’t work, call a licensed HVAC technician for help.

DIY Troubleshooting for AC Noise

A lot of air conditioner noises are easy to fix with some basic maintenance and troubleshooting. Here are some steps homeowners can take to quiet their noisy AC:

Replace Air Filters

Air filters play a big role in preventing AC noise. If you replace them regularly, your AC unit will run smoother and quieter. To replace your air filter, simply remove the filter cover, take out the old filter, and insert a new one that is the correct size and type. Then, put the filter cover back on.

Changing filters regularly can prevent airflow issues that lead to system strain and noise. If you aren’t able to change the filters yourself, you can look into HVAC home warranty companies that offer coverage for AC repair costs or filter replacement.

Clean the Coils

Dirty coils can cause the system to work harder and make more noise. To clean the condenser coils:

1. Turn off power to the AC unit to ensure safety.
2. Remove debris from around the outdoor unit.
3. Unscrew and remove the top grill to access the fan and coils.
4. Clean out any debris around the fan to ensure smooth operation.
5. Use a coil cleaner spray to remove buildup.
6. Rinse gently with water, avoiding excessive pressure to not bend the coil fins.
7. Allow the unit to dry completely before restarting the system.

If your coils are damaged, you may need to replace them altogether. To budget out your repair costs, check out our guide on air conditioner coil costs. For more information on cleaning your air conditioner coils, watch the video below.

Check for Loose Parts

Loose parts are a very common problem in AC units, but tightening up bolts and screws is an easy DIY fix. Simply turn the AC power off, remove the access panel, inspect for any loose parts, and tighten any fasteners. Once the parts are tight again, you can turn the power back on.

Inspect for Refrigerant Leaks

While you can’t repair refrigerant leaks yourself, you can still check for warning signs. Some common signals of a refrigerant leak are ice buildup on the evaporator coil or refrigerant lines, hissing sounds near the coils or lines, and oil stains in or near the AC system.

If you see any of these signs, call a professional HVAC technician to patch any leaks and refill your system.

Professional Repairs for Persistent Noise

You can fix a lot of AC problems with DIY methods, but some issues require professional help. If you still have issues after taking the troubleshooting steps above, call an HVAC company.

Air conditioner repair costs are expensive but well worth it in the long run. According to Angi, the average HVAC repair costs $350, but repairs range from $130 to $2,000. Addressing problems before they escalate can help cut down on repair costs and keep your system running smoothly.

Preventing Future AC Noise

To keep your air conditioner running quietly in the future, you should schedule regular professional maintenance to identify and resolve issues early on.

HVAC maintenance costs are steep but almost always less expensive than the cost to repair. Keeping up with regular maintenance also extends the life of the unit, which is a perk for both your home and your bank account.

If you’re considering AC repair, fill out the form below to get quotes from some of the best air conditioner brands on the market.