3 Common HVAC Noises and What They Mean

HVAC Noises

Sometimes, you don’t even know there’s a problem with your HVAC until it’s too late. This often stems from the fact that we just don’t know the signs and are therefore blind to indicators of trouble. One of the most obvious signs that your HVAC is malfunctioning is the uncharacteristic sounds coming from the appliance itself.

Normally, you don’t even notice the sounds your HVAC makes because it’s just not very noisy, aside from usual hums or the whooshing of air through vents. Plus, let’s face it: if we’re not confronted with the consequences head-on, we assume all is right and dandy in the world. Ignorance is bliss, right? Wrong. If you hear anything disruptive, chances are it’s time for a serious inspection by a certified contractor in your area.

Here’s a list of the most common HVAC noises and what they mean so you can resolve the problem sooner!

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Do you hear something coming from your system that sounds like the clamor of banging pots and pans? This “clanking” is abnormal and could mean parts are loose, like the blower motor fan or blades/pipes that are colliding. Clanking sounds are up there with more severe issues because of the costs associated with replacing broken or loose parts. If you hear these kinds of noises, shut off your system and call a technician immediately.


Hissing is typical when air leaks from your system. If you hear it in your walls, your ducts could be leaking, too. This isn’t only a nuisance, but it’s also costly because the air that should be circulating throughout your home is now retreating into your walls.

First, use your best judgment to measure the volume of the hissing. Loud hissing noises from your ducts generally signal duct repair beyond the scope of even the most seasoned DIYer. Minimal hissing could mean an issue starting in your air vents. Sometimes these hissing sounds happen when air filters are loose or not the right size, thus causing an opening in the seal. The air is then bypassing the filter by going around it instead of being pulled through the filter. This, on the other hand, is a relatively simple fix that a technician could walk you through so you know what to do if it occurs again.


If rattling noises are coming from your outdoor unit, it could mean debris (twigs, rocks, etc.) is caught inside. HVAC grates are made thin enough to block large obstructions, but occasionally things slip through. In this case, the best thing to do is turn off your system, cut the power to the unit, and remove the debris. Any visible damage to the condenser coils, compressor, or fan should be repaired by an HVAC technician. Internal rattling in your furnace or other components is treated similarly: turn it all off and call your HVAC technician, as these stoppages are harder to remove.

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