Updated On

November 9, 2023

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    Your air conditioning unit is making a weird noise. Maybe it’s working fine, or maybe you’ve noticed the air is not flowing with as much force as it used to. Maybe the air is not as cool as it should be. 

    If things seem to be working, what’s the problem? Maybe if you ignore it, it will go away. That’s not the best plan. You want to know what that noise means, and if there are problems beyond the noise, you want to find out if and how the two things are related. You want to know if the sound means there are bigger problems hidden in that HVAC unit. But if you feel uncertain right off the bat, it’s better to find an HVAC company now:

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

    Is This Air Conditioner Noise a Big Deal?

    Should you be concerned about a little bit of extra squeaking, pulsating, humming, or hissing from your AC unit? The short answer is yes. But not all air conditioning system noise is problematic, so it’s important to know the difference and know what noises are a bigger cause for concern.

    You might want to explore our article to discover the causes of pulsating sounds in ACs and possible solutions.


    How Air Conditioners Work

    A basic understanding of how an air conditioner works can help in deciding what noises are normal and when they are a cause for concern. Air conditioners remove heat and humidity from inside a home and transfer it to the outside, and then blows cooler air inside.

    The evaporator is what removes heat from inside air, while the condenser releases that warm air into the outside. Then the compressor moves refrigerant between the evaporator and the condenser to chill the indoor air, and the blower disperses cool air inside. And of course, there’s a thermostat that regulates how cool you want the inside of your home to be. 

    All these complicated processes carried out by these moving parts make noise. While some noises are perfectly normal, others might raise concerns.

    This is why having a suitable home warranty for HVAC systems is crucial. It ensures that you have peace of mind and financial protection in case any unexpected issues arise with your heating, ventilation, and air conditioning system.

    “Normal” Noises

    Air conditioners make noise, so first things first, let’s cover normal noises. There is the “startup” noise of fans and other moving parts gearing up all at the same time. No big deal.

    There is the ongoing fan noise that should be just a low hum as air blows through the ductwork and out through the vents. 

    You might also hear some clicks as the unit powers down until the thermostat changes and air conditioning is needed again.

    Ok, so there are sounds that are truly no big deal. What should you be listening for to check on problems that may be happening in your air conditioner?


    What Could This Air Conditioner Noise Mean?

    You’ve probably heard these noises before, a noise unlike the normal startup or running of the air conditioner. What are some of these noises, and what could be the problem that the noise points to?

    A humming or buzzing noise is less serious but could lead to bigger problems if not investigated. Humming is likely caused by some loose parts like fan blades vibrating against another part of the unit. For instance, loose refrigerant piping could lead to a refrigerant leak down the road.

    You will likely hear clicking sounds when the unit starts up and shuts down. That’s not a problem. If the clicking is constant, there might be a problem, like a thermostat that is not working properly, or a defective control. Clicking is usually related to the parts of your AC system that are directly related to the electrical system, so if it is happening after startup, you’ll want to deal with that electrical problem sooner than later.

    You might not notice this sound unless you are near the AC condenser. But a hissing or bubbling sound is not great news. A likely cause can be a refrigerant leak. You’ll want to have a licensed HVAC technician do some diagnostics to locate and fix the leak. 

    There are a number of possible causes for a loud noise like screeching or squealing noise, and if it does not stop right away after startup, none of them are good news. It could be a loose fan belt, or an outdoor unit fan motor or blower motor that is about to go bad. A squealing sound could also mean you have a refrigerant leak. 

    If the sound persists beyond startup, this is the kind of sound that will alarm most homeowners to investigate and take action. 


    Should I Try and Fix it Myself?

    When it comes to AC repair, for the most part, beyond the investigative phase, if you hear a strange noise, these problems should be left to licensed and trained HVAC professionals. Finding and fixing a refrigerant leak requires special equipment and know-how, and replacing parts on your own could nullify any warranties or insurance claims that you may need to file in the future.

    If a humming sound leads you to a few loose parts that need to be tightened up, that’s probably something you can handle on your own. But beyond that, unless you have the training yourself, it’s best to leave HVAC system repair to the pros. 

    For more information on your noisy air conditioner, check out the video below:

    A low hum or a clicking sound at the start or stop of running your AC unit is normal operation. But if the hum gets louder, or if you hear noises that you haven’t heard before – like hissing, screeching, or a banging noise – it’s time to turn off the unit and contact a trained HVAC technician. That noise may not be the end of the world, but it could mean a crucial part of your AC unit has gone bad, and running it in spite of that sound could lead to bigger problems and system failure. 

    When it comes to loud and persistent noise from your air conditioner, it’s better safe than sorry. Fill out this quick form to get in touch with the best in the business:

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    Editorial Contributors
    avatar for Jonathon Jachura

    Jonathon Jachura

    Contributor

    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.

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    photo of Roxanne Downer

    Roxanne Downer

    Editor

    Roxanne Downer is a commerce editor at Today’s Homeowner, where she tackles everything from foundation repair to solar panel installation. She brings more than 15 years of writing and editing experience to bear in her meticulous approach to ensuring accurate, up-to-date, and engaging content. She’s previously edited for outlets including MSN, Architectural Digest, and Better Homes & Gardens. An alumna of the University of Pennsylvania, Roxanne is now an Oklahoma homeowner, DIY enthusiast, and the proud parent of a playful pug.

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