Grinding Noise in the Air Conditioner

Written by steve smith
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Grinding Noise in the Air Conditioner
Air conditioner fans and grates often cause grinding noises. (Comstock/Comstock/Getty Images)

Air conditioners make many different types of sounds and noises, from clanking and humming to grinding and churning. Some confusion surrounds what each type of noise means, and, because describing the noises is difficult, you should examine all the reasons for the noises before determining what to do.

Blower Fan Belt

If your air conditioner is making a grinding sound, the fan belt may be catching or rubbing on a loose part. This belt attaches to the fan blower inside the blowing unit. The belt is a chain, so when a part rubs against it, a grinding noise occurs. Since this is a complicated repair, contact a professional air conditioning repair man to fix this issue. Most of the air conditioner is disassembled to fix this problem because the blower unit is located inside the unit behind the blower grate.

Fan Blades

Another possible problem is a bent fan blade or broken grate. If the fan blade is bent and contacting the grate, it causes a grinding, rattling noise. The sound comes from the constant, repetitive striking of the blade against another metal part, which is also a complicated repair. To fix this problem replace the entire fan, or bend the blade straight. Replacing the grate or bending the grate back up also solves the problem. Do not remove the bent grate piece completely because this allows foreign objects like twigs and leaves to enter the air conditioner.

Piston Rods and Compressor Issues

Another possible issue lies within the compressor. When the piston rods inside of this part fail, a grinding sound that is more like a constant clanking and banging occurs. This repair is costly and difficult because the entire compressor needs replacing. Another possibility is loose hardware on the compressor mounting brackets. The brackets hold the compressor in place so it does not shake when operating. When loose, the brackets rattle and the noise often sounds like grinding. A repair technician can replace the brackets and remount the compressor to solve this issue.

Loose Nuts and Bolts

Loose nuts and bolts cause grinding sounds in some cases. These loose nuts or bolts clank around inside the air conditioner, rub against the fan blades or rattle around in the blower unit. If the grinding sound is metallic in nature, this is most likely the problem. This sound often occurs after a servicing or when a new part is put in place. Removing the nut or bolt is the simple way to solve this issue. If you are unfamiliar with air conditioners, contact a service technician to inspect the unit and find the loose piece of hardware.

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