Updated On

November 9, 2023

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    If you got a sinking feeling when you realized the horrendous noise you heard outside was your air conditioner compressor, we understand. 

    Malfunctioning air compressors can make ear-piercing clanking, buzzing, humming, rattling, and squealing noises that keep you and your neighbors awake at night. 

    Doing some research if your HVAC system is making noise is wise. Running your unit with malfunctioning components could cause further damage.

    To learn more about the sound your compressor is making we recommend you read our article titled why AC makes loud buzzing noise, also take a look at this video:


    What Is An Air 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 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.

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    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 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 compressor is malfunctioning, it often causes other parts to breakdown, because it does not push the right amount of refrigerant through the system. Air 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 Can You Prevent Air 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 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. 

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    Final Advice For Dealing With A Noisy Air 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 air 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.

    Editorial Contributors
    avatar for Alexis Bennett

    Alexis Bennett

    Contributor

    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.

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    photo of Andrew Dunn

    Andrew Dunn

    Senior Editor

    Andrew Dunn is a veteran journalist with more than 15 years of experience reporting and editing for local and national publications, including The Charlotte Observer and Business North Carolina magazine. His work has been recognized numerous times by the N.C. Press Association and the Society of American Business Editors and Writers. He is also a former general contractor with experience with cabinetry, finish carpentry and general home improvement and repair. Andrew earned a degree in journalism from the University of North Carolina at Chapel Hill, as well as a certificate in business journalism. He lives in Charlotte, N.C.

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