Wednesday, August 30, 2017

Common Air Conditioner Noises and What They Mean

On a hot day, the last thing you want when you turn on your air conditioner is for it to start making noises that remind you of a 747 heading down a runway or rocks being tossed around inside a steel drum. The following are a few of the most common air conditioner sounds that you might encounter and what they mean.

You turn on your AC and hear a high-pitched screaming or hissing sound similar to a tea kettle coming from the outside unit that stops within a few seconds. The air conditioner may also cycle on and off frequently. This is usually the result of high pressure building up in your system and causing the compressor to scream. You should immediately turn off your AC and call for service.

Knocking, Banging, or Clanging:

If you notice this sound when the outside unit is running but not when you set the thermostat to fan only, the most likely cause is an obstruction. The fan may be hitting a rock or stick or may have come loose from the mount causing it to wobble inside the cage. You should turn your air conditioner off and call for service.

Gurgling or Bubbling:

It may be hard to identify the source of the gurgling, but it is most likely the condensate drain line or a refrigerant leak. You probably will not make the problem worse by continuing to run your AC, but you should make sure that you have a proper trap for the condensate drain line. You should also call a professional to rule out a refrigerant leak.


A metal-on-metal screeching sound while the AC is running typically indicates that the fan motor bearings are worn and that the fan motor should be replaced. You should avoid running your AC if possible and call for service.


If there is an intermittent squealing coming from the inside unit, you may have a worn or misaligned fan belt. The sound may come and go as the belt expands and contracts with changes in heat and humidity. Your AC may continue to run for a while, but it is best to go ahead and call for service since the belt will eventually break and leave you sweltering in the heat.


If you hear a sound similar to a baseball card in the spokes of a bicycle tire, there is probably a small obstruction in the fan of the outdoor unit. You should remove the obstruction before continuing to run your AC. If the outside unit tries to turn on but only clicks, you may have an electrical problem involving the compressor, thermostat, or capacitor.

Any type of strange noise coming from your AC should be evaluated by a trained HVAC professional. J.R. Perkins Heating and Cooling has been serving homeowners in Scottsdale and the surrounding area since 1960. Call (480) 422-4437 today or visit our website to have one of our licensed HVAC experts make sure that your AC is ready for the hot weather to come.