Strange AC Noises and What They Mean

There are some noises that you normally would expect to hear when your air conditioning is running. However, if you hear any of the following four sounds, it is time to hire a professional AC repair service.


If you hear a squealing sound coming from your indoor AC unit, it could be its fan belt. This is a common problem that is caused when the belt becomes worn or is misaligned. The sound could be intermittent or more noticeable when temperatures or humidity levels change, which causes the belt to expand or contract. You can continue using your cooling system, but you should schedule a repair because the belt will eventually break.

High-Pitched Scream or Hiss

If you hear a high-pitched scream or hiss coming from your AC’s condenser outdoors, it could be that pressure has built up in the compressor. Your air conditioner may turn itself on and off frequently. In this case, you should turn off your system and schedule a repair because this could be a dangerous condition.

Clanking or Banging

If you hear clanking or banging noises coming from your outdoor unit, it could be as simple as a small tree branch having fallen into the cabinet. Or, it might mean that the fan is wobbling because it is loose and hitting the sides of the cabinet. If there is a stick, you may be able to remove it on your own after you turn off the power to your unit. You will need to call in a professional if it is your fan that needs to be repaired, though.


A screeching metal-on-metal sound that starts when your air conditioner turns on could be a sign that the fan’s motor bearings are wearing out. You should get professional help as soon as possible because this could cause your fan’s motor to seize.

Reliable AC Repair

Do not ignore strange noises coming from your air conditioning system. Contact Evans Mechanical to schedule your repair service today. We have been providing reliable heating and cooling repairs, maintenance, installations, and indoor air quality solutions for more than 25 years to residents of Eureka, CA, and the surrounding areas.

Tags: , ,