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5 Air Conditioner Sounds Your System Should Never Make

5 Air Conditioner Sounds Your System Should Never Make

June 17, 2019

Air conditioners are complex machines. Like any other machine, they make noise, but there are some air conditioner sounds you don’t want to hear. Before you get hot under the collar, try these troubleshooting tips to see if you can find and fix the problem.

Squealing or Screeching

Squealing or screeching noises from the indoor or outdoor blower motor indicate a frayed belt or problems with the motor bearings. If it’s a worn belt, it should be replaced before it breaks and the fan stops rotating. If the sounds are coming from a blower motor, turn off the system and contact your HVAC professional.

Clanking Sounds

The outdoor blower assembly is exposed to the elements. It’s inevitable that debris falls into the unit. Sometimes the debris becomes lodged in the fan blades and makes a clanking or “thwapping” noise. If you can see the obstruction, you can try fishing it out. Make sure power to the air conditioner is turned off at the outdoor disconnect box.

Rattling or Banging

Rattling or banging are sure sounds that something has come loose or broken. The sounds could be caused by loose motor mounts, a misaligned motor or rattling air ducts (though not technically an A/C component). Motor mounts and motors may be tightened and aligned, respectively, if you feel confident. Seal duct leaks with duct mastic and metal tape.

Humming or Buzzing

Humming or buzzing is a sign of a failed capacitor. If you’re handy with do-it-yourself projects and have the correct tools, you may be able to change the capacitor, though it’s not a job for an amateur. Consulting your HVAC tech is the smarter way to go.


Rapid or intermittent clicking sounds are indicative of an electrical signal problem, which could originate with the thermostat or with the relay located next to the capacitor. Check the thermostat’s wiring for tight connections. Changing a relay requires the same handy skills and tools as changing the capacitor.

If you need help diagnosing unusual air conditioner sounds in your greater Cleveland home, contact Geisel Heating, Air Conditioning & Plumbing.



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