Sounds Like a Problem – 6 Noises Your Air Conditioning Could Be Making

“What’s that noise?” It’s a question that you don’t want to ask in regards to your central air conditioning. But the reality is that ACs are complicated systems with many moving parts. Even if just one of those parts is off in some way, it could cause a startling noise, which might be the sign of a more troublesome problem.

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The first thing you want to do is try to identify the type of noise and where it’s coming from. This can be useful information when troubleshooting and fixing the issue. Air conditioning noises can be hard to describe and subjective – but in general, we break them down into a few different categories.


You notice a banging sound coming from the outdoor AC unit. This most likely means that the fan inside the unit is hitting an obstruction or is loose.

What to do: Shut off the unit and call an HVAC professional. Opening the unit could result in an electric shock if you aren’t experienced with this equipment.


Some customers call about a strange squealing noise that occasionally comes from the inside unit, but aren’t sure if it’s a serious issue. A likely explanation is a worn-out or misaligned belt that connects the fan to the motor.

What to do: Take this as a warning sign that the belt is on its last legs. You should still be able to use the AC but eventually the belt will snap and the unit will stop working entirely. Our recommendation is to have it replaired before that happens.

High-pitched hissing

If the outside air conditioning unit makes a high-pitched hissing or screaming noise (specifically when it first turns on), it could be a sign of excessive pressure inside the compressor.

What to do: Shut off the unit and call an HVAC professional. If the pressure gets too high it can be a very dangerous situation.


There are few things that could cause a clicking sound from the outdoor unit. If it happens when the unit is on, then it could be a small piece of debris stuck in the fan. However, if the clicking occurs when you try to turn the unit on, that’s a sign it’s an electrical issue with the compressor, capacitor, or thermostat.

What to do: It’s always better to be safe than sorry with an electrical issue. If you can’t easily remove the small obstruction, have an HVAC professional take a look and determine the problem.


The awful sound of metal scraping against metal coming from the outdoor unit could mean that the fan motor bearings are worn out.

What to do: Turn off the unit or limit its use as much as possible. Putting off this repair can make the situation much worse.


Sometimes described as a bubbling sound when the AC is running. The confusing part is that it can be tricky to locate where this noise is coming from. It could be bubbles in the condensate drain line, or there may be a refrigerant leak.

What to do: Check the condensate drain line to make sure it is clear and draining properly. If everything looks good there, have an HVAC professional check for a refrigerant leak.

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One thing is for sure – if there’s a strange noise coming from your air conditioning, there’s an issue that needs to be fixed. For experienced repair service, call Baylor Heating & Air Conditioning, Inc. a call at (812) 425-8435.

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