Common HVAC Sounds and What They Mean

common hvac sounds

“Clank, hiss, pop.” There aren’t sounds you should be hearing from your HVAC system. They indicate that there could be a problem!

Obviously, some level of noise is expected when you run your furnace or AC, but if you’re hearing much beyond that, there may be an issue at hand. These issues could range from bad blower belts to faulty electrical equipment and much more. As always, you should contact a professional to get any of these problems fixed if you notice them. 

Here are some of the common noises you might hear coming from your HVAC system, what they mean, and what to do when you hear them!


If you hear squealing, it means you may have an issue with the belt on your blower. This is a similar sound/issue that plagues many car owners; you’ll recognize the noise when you hear it. Additionally, a squealing sound could mean that the motor needs more lubricant. 

In any case, it’s best to call a professional to handle the issue for you. If you let the squealing go unfixed, the resulting friction over time could cause expensive damage to the rest of the system. 


Clanking is a surefire sign of a problem with your HVAC system. Why? Clanking indicates that there is external debris or loose components within your system. HVAC systems are very precise, with components and parts that fit perfectly together. So when you hear something clanking and rattling around that wasn’t there before, it means your system has an unwanted guest inside. 

First, check your vents. If you can see some debris in the grate that you can clear out safely yourself, give it a shot. However, if the problem persists or if you are unsure of where the clanking is coming from, always call a professional. 

Get the issue fixed by a professional ASAP, as debris hanging out in your vents for a while could lead to expensive damage to your HVAC system and your home if it’s left unaddressed.


No, there’s not a cat inside your vents. Well, let’s certainly hope not. 

Hissing coming from your HVAC system means that air is escaping where it shouldn’t be. Try to locate the source of the hissing; it might clue you in on what repairs may be necessary. 

If the hissing sounds like it’s coming from inside your walls, you likely have an issue with your ducts. Malfunctioning ducts can lead to the air flowing into your interior spaces between your walls, instead of in the areas of your home that you actually occupy like bedrooms or the living room. This leads to wasted energy, as your HVAC system has to work harder to keep your house warm in a way it’s not supposed to operate. 

For issues with your ducts, call a professional to come help. This isn’t a DIY job. Plus, you’ll benefit from energy savings and a more comfortable home after you get the problem resolved.

If the hissing noise is coming from your vents, it could be caused by your air filter being placed incorrectly. You can usually correct the issue yourself by readjusting the air filter, but if the problem persists be sure to ask a professional for help. 


Whistling indicates a high-pressure leak within your HVAC system, which is a major issue that a professional should handle ASAP. The noise will sound similar to a hot tea kettle, and if you hear it you need to act quickly. 

High-pressure leaks of any sort are a serious problem since they can damage the system quickly.

High-pressure leaks usually occur in the refrigerant line of your home’s cooling system. If your system is losing refrigerant fast enough to whistle, you need to have it serviced right away. Wait too long, and your AC might not really work as AC. 


Hear clicking coming from your HVAC system? The cause of the sound might vary depending on if it’s coming from your AC or your furnace.

If the clicking is coming from your furnace and is persistent, there could be an issue with your ignition system. This issue should be addressed by an HVAC technician to prevent further damage to your heating system. 

On the other hand, if the clicking is coming from your AC system, you could have an issue with your compressor or air handler. Once again, these components aren’t DIY fixes, make sure you have a professional check them out. 


A popping noise indicates a serious issue that can lead to safety hazards and expensive damage if the problem isn’t addressed. It is likely being caused by one of two things: a break in a wire or conductor, or moving components getting stuck/hitting each other. 

Both causes are serious issues, so if you hear them you need to turn off your HVAC system and call a professional ASAP to come take a look.

Hoosier Indoor Air Quality Can Help

If you’re in McCordsville, Indiana, and hear any of the sounds we mentioned earlier in your home, be sure to contact Hoosier Indoor Air! We’ll come to your service to diagnose and fix the issue. Plus, we’re here for any other HVAC needs. 

Whether you need emergency heating repairs, new furnace installation, or seasonal furnace maintenance, Hoosier Indoor Air is here to help keep you warm during the cold Indiana winters. 

We’ll take care of your HVAC needs so you don’t have to worry about them, allowing you to just focus on living your life. 

One of the ways we do this is through our Comfort Guard™ maintenance plan! 

This service includes more than just routine maintenance. It also offers discounts and perks for heating and cooling repair services—and more—for just $18 per month! 

Our certified HVAC technicians are standing by and equipped to handle any type of heating problem in your home. To schedule an appointment or learn more about how we can serve you, call 317-466-7437 or book a visit online.

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