Why Is My Air Conditioner Making a Screeching Noise?

July 15, 2015

Does your air conditioner make a loud, high-pitched screeching noise when it runs or starts up? Perhaps a metal-on-metal sound like when a train is braking to stop on the tracks?

That’s not a pleasant noise. And it’s probably not good for your air conditioner either. Please contact a professional AC repair company to diagnose and fix this problem. Continuing to run your air conditioner could cause bigger problems that result in even more costly repairs down the road. 

For your reference, here’s a list of some of the most common causes of this screeching noise.

If the noise is coming from the outside unit...

If the screeching screeching noise is coming from your outside AC unit, there are 2 probable causes: the fan motor or the compressor.

Fan motor

The fan on your outside unit is responsible for blowing air over the condensing coils, which helps remove the heat from the refrigerant. The bearings on the motor may be shot, leaving the fan to screech as it turns. 

 If this is the problem, you’ll probably hear the screeching the entire time your air conditioner is running.
 
The fix: You need an AC repair tech to replace the fan motor.

The compressor

The compressor is responsible for ‘compressing’ the refrigerant in your air conditioning system so that it can help cool your home’s air. The compressor itself has a motor that can begin making a squealing or screeching noise when it has gone bad. 

 
If this is your problem, you will likely hear the noise when your AC unit starts up (or tries to). 
 
The fix: You need to replace the compressor. Unfortunately, that usually means you’re best off replacing the entire AC system (unless it’s under warranty). Contact us for more info.

If the noise is coming from the inside unit…

If you’re hearing a screeching noise coming from the attic or closet where the inside unit of your air conditioner is located, the most likely causes are a blower motor bearing or a worn belt

Blower motor

Your inside unit has a fan (commonly called the blower) that blows air over the cold evaporator coils in your inside unit. The bearings in this motor can go bad, resulting in loud screeching noises when your AC runs.
 
The fix: The fan motor will need to be replaced by an air conditioning repair professional.

Belt slipping/wearing

Some air handlers have belts that spin the blower fan. The belt may be worn or misaligned, creating a screeching noise.
 
The fix: The belt may need to be replaced or adjusted.

Get a pro’s help

All of these fixes should be performed by a trusted, professional air conditioning repair technician. If you need someone in the Kansas City area, contact us today.