Updated On

May 14, 2024

Why You Can Trust Us

Today’s Homeowner exists to help you maintain or improve your home safely and effectively. We uphold strict editorial standards and carefully vet the advice and resources referenced in our articles. Click below to learn more about our review process and how we earn money.

Learn More

    If you got a sinking feeling when you realized the horrendous noise you heard outside was your air conditioner compressor, we understand. Malfunctioning AC compressors can make ear-piercing clanking, buzzing, humming, rattling, and squealing noises that keep you and your neighbors awake at night. 

    A compressor can make noise for several reasons – worn bearings, loose parts, no oil, and electrical issues.

    To learn more about the sound your compressor is making, we recommend you take a look at this video or scroll down to learn more:

    What Is An AC Compressor?

    Your AC compressor is a part of the condenser unit or your outdoor unit. The compressor is responsible for heating and pressurizing coolant from the evaporator coil before the condenser cools and compresses it. 

    When your compressor is malfunctioning, it often causes other parts to breakdown, because it does not push the right amount of refrigerant through the system. Air conditioner compressors are high-pressure part that takes a lot of wear.

    So, it is not uncommon for compressors to fail, especially if you own an older air conditioning system.

    If you’re looking for a trusted, industry-leading home warranty company, we recommend Choice Home Warranty. Choice Home Warranty is an industry leader in providing home warranties for HVAC systems, and right now you can take advantage of their current promotions that get you $50 Off + 1 Free Month and Free 30-Day Cancellation. 

    Also, if you’re on a budget, you can explore some inexpensive home warranty options available in the market.

    Do Loud Noises Mean Your Compressor Is In Trouble?

    Honestly, it depends on the sound. It is normal for your compressor to make some noise when it is running. However, strange sounds coming from your AC unit might mean a costly component, like your air conditioner’s compressor or blower fan motor, is failing. 

    So, read through the common causes of AC compressor noises to help you pinpoint what is causing your compressor sound.

    Squealing Sounds

    A squealing sound while your compressor fan motor is running is a telltale sign that you may need to replace it soon. Worn bearings cause the horrendous shrieking.

    Rattling Noises 

    Rattling sounds could be something as simple as a loose part, improperly installed air filter, or airflow causing your ducts to vibrate. Or, it could be something more serious, like a broken fan blade. 

    Clanking Sounds

    Clanking noises usually come from the air condenser fan. When it begins to fail, it can get off balance due to the worn-out parts that cause it to bang against the condenser coil, which creates the clanking noise. 

    Clanking is one of the worst AC compressor noises because it can mean your outdoor unit is breaking down. Or the broken fan caused damage to other components in your air conditioning unit.

    So, you may be looking at replacing the compressor or your entire HVAC system soon. 

    Did You Know

    When your AC compressor is malfunctioning, it often causes other parts to break down because it does not push the right amount of refrigerant through the system. Compressors are a high-pressure part that takes a lot of wear.

    Banging Noises 

    Your AC damper is usually the culprit when you hear a banging sound as your air conditioner shuts down. The damper makes the loud banging sound because internal pressure changes caused by the air conditioner powering off, pull the damper closed. 

    The sound is pretty distinct and you have likely heard an air conditioner unit damper slamming shut many times. If the sound bothers you, you may want to have an air conditioner repair technician adjust the damper, so it is not as loud when it closes. 

    Banging noises can also come from broken piston pins and crankshafts hitting the inside of the crankcase in your compressor motor.

    Hissing Noises

    Refrigerant leaks can cause a hissing noise as the refrigerant gas escapes from your unit. If you hear hissing from your air conditioner, you need to contact an HVAC professional. 

    Under normal operation, refrigerants do not pose a threat to homeowners. However, refrigerants are toxic gases that are harmful to the environment and humans or animals if inhaled or ingested.

    Related: What is Compressor Oil?

    How Much Does It Cost to Fix an AC Compressor?

    If your compressor in your air conditioner needs to be repaired, the cost ranges from $150 to $650, depending on the issue. Replacing capacitors and contactors will be on the lower end, while extensive repairs will be more costly. If you need to replace your AC compressor, it will cost between $1,000 to $2,600, unless it is still under the manufacturer’s warranty.

    How Can You Prevent AC Compressor Noises?

    Caring for your HVAC system can keep it running well, which should help to reduce noisy system breakdowns.

    When you have your air conditioner and furnace maintained annually, the HVAC technician will go over your entire system to ensure all of the components are working and your refrigerant levels are correct. The contractor will advise you of any parts that are worn and give you the option of replacing them.

    Even if you decide to wait until major components like your air condtioner compressor stop working to replace them, you will have an idea of your compressor’s condition long before it starts making strange sounds. 

    If you keep up with your air conditioning maintenance and your compressor starts clanking or squealing, you will know, you need to schedule an appointment to have it looked at. 

    Get HVAC Estimates In Just 30 Seconds
    Then connect with local experts to get the help you need.

    Final Advice For Dealing With A Noisy AC Compressor 

    Having an air conditioner tuneup is a good idea anytime you hear a strange sound coming from your compressor, especially if you have tried to identify the source of the sound unsuccessfully. 

    When your AC compressor makes strange noises at start-up or when it is shut down, it is usually a sign that a unit or your HVAC system needs repairs or a replacement soon anyway, and the longer you let it wait, the more stress is put on parts like the piston pins, gaskets, and connecting rods. 

    If you have not yet planned for the cost of replacing damaged or loose parts, it would be wise to start now. A wise way to protect yourself from unnecessary expenses on home appliances is to get a home warranty protection.

    Frequently Asked Questions

    Why is my AC compressor making a loud buzzing noise?

    Loud buzzing noises coming from the outdoor unit of your air conditioner are usually caused by electrical issues with the compressor. Most often, it’s from loose wiring, a failing capacitor, or a bad contactor. An HVAC technician can help diagnose and fix the issue.

    How often should I have my AC compressor serviced to prevent noise issues?

    I recommend having your air conditioning system serviced by an HVAC technician at least once a year.

    Can I continue to run my air conditioner if the compressor is making noise?

    If the noise is loud and some out of the ordinary, I recommend turning off your AC unit until an HVAC contractor can assess it. Running it while its damaged can cause further, more expensive issues.

    Article Update Log
    Reviewed for accuracy, cost data, industry best practices, and expert advice by Jonathon Jachura.
    Editorial Contributors
    avatar for Alexis Bennett

    Alexis Bennett


    Alexis is a freelance writer with nearly a decade of experience covering the home services industry. She’s built considerable expertise in roofing, plumbing, and HVAC, as well as general construction and real estate matters. In her free time, Alexis enjoys coaching women’s golf. She lives in the Triad area of North Carolina.

    Learn More

    photo of Jonathon Jachura

    Jonathon Jachura


    Jonathon Jachura is a two-time homeowner with hands-on experience with HVAC, gutters, plumbing, lawn care, pest control, and other aspects of owning a home. He is passionate about home maintenance and finding the best services. His main goal is to educate others with crisp, concise descriptions that any homeowner can use. Jon uses his strong technical background to create engaging, easy-to-read, and informative guides. He does most of his home and lawn projects himself but hires professional companies for the “big things.” He knows what goes into finding the best service providers and contractors. Jon studied mechanical engineering at Purdue University in Indiana and worked in the HVAC industry for 12 years. Between his various home improvement projects, he enjoys the outdoors, a good cup of coffee, and spending time with his family.

    Learn More