3 Common Causes of Noisy Air Conditioners

Modern air conditioning systems are relatively quiet, and though some noise is to be expected, any sounds that are new, unusual or that have become louder should be investigated to prevent expensive damage to your system. Three of the most common sources of abnormal sounds include the fan belt, the electrical system, and the compressor, and they should be thoroughly inspected if your air conditioner is noisy or suddenly louder than normal.

Blower Fan Belt

Inside the air handler, especially in a commercial application, a belt connects the blower motor to a squirrel-cage fan, which is used to move air through ducts of your home. Over time, the belt can stretch or begin to crack, and the pulleys on the motor and the fan can lose lubrication or become misaligned. A stretched belt can cause screeching sounds as it slips, and a cracked belt can start thumping as pieces break away. Pulleys that are starved of lubrication or misaligned can begin to whine or screech, as can the blower motor if it’s not properly lubricated. Have the belt adjusted or replaced, if necessary, and check the pulleys and blower motor for proper lubrication and alignment. Failing bearings can also cause this type of noise.

Electrical System

Faulty electrical contacts, relays, and capacitors can cause many strange noises in a system, including clicking as relays or contacts fail to engage properly or buzzing as the start capacitor fails to start the compressor properly. Have the electrical system inspected, cleaning any dirty contacts and replacing burned or faulty components.


Problems with the compressor can cause screeching, whining, thumping, buzzing or hissing noises. If it’s hissing, there’s likely a refrigerant leak; and if it’s buzzing, the start capacitor may have failed. Screeching, whining, thumping or other noises may indicate serious problems with the compressor, such as damaged pistons or scrolls, lubrication failure or worn brushes. Have the compressor inspected immediately to avoid unnecessary damage.

If your air conditioner is noisy, talk to our HVAC experts at Conditioned Air today to determine the cause of the problem. We serve the Southwest Florida area, including the communities of Naples and Sarasota.


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