Fixing a Noisy Window Air Conditioner

What You'll Need
Fin comb
Light oil (SAE 10)
Garden hose
Shop Vacuum
Replacement parts as needed
Air conditioner weatherseal

One of the most common types of problems people can experience with a window air conditioner is unusual noise. The noise can be an annoying rattling or a loud hum. Sometimes the noise can easily be fixed, especially if it's caused by movement of a few loose parts. Other times a noisy air conditioner is a sign that the unit is beyond repair.

You can save yourself a lot of money by trying some of these easy and common fixes to alleviate the problem. If none of these solutions work, you may want to either hire a professional or replace the unit.

Step 1 - Make Sure the Unit is Properly Installed

The annoying rattling sound you hear may simply be because the air conditioner is no longer tight in the window frame. The vibrations of the running air conditioner could be causing the unit to shake and lightly bang against the frame. Check to see if this is the problem by pressing your hand against the window glass, then listen for any change in the noise. To fix this problem, push air conditioner weather seal tightly around the unit to reduce movement. Placing shims between the frame and the unit also works.

Step 2- Check Front Panel Screws

A rattling sound could also be caused by a loose front panel. This is an easy fix and simply involves tightening the screws. If there's still some movement, try using putty to tighten the panel to the unit.

Step 3- Examine the Fan Blades

A possible cause of a grinding noise is loose insulation stuck to the fans. To find out if this is the case, turn off the unit, take off the faceplate and check the fans. Remove any foam insulation and discard.

While you're at it, check the fan blades to make sure they're even. A bent or uneven blade can bang against the interior of the air conditioner and cause an annoying rattling sound. Slowly rotate the blades manually. If any blade is rubbing or scraping the side of the unit, carefully bend it back into place.

Step 4- Lubricate the Fan Motor

An improperly lubricated motor can also cause a loud hum, but can only be fixed if the motor housing isn't permanently sealed. If you can remove the motor housing, take off the caps from the ports and add a few drops of SAE 10 oil to each port. Add a couple of drops of oil along the motor shaft and manually rotate the fan to spread the oil.

Step 5- Straighten the Coil Fins

Damaged coil fins can cause a loud hum. To fix this problem, take off the housing that covers the cooling coils. This is usually located at the back of the unit so you may need to remove the air conditioner from the window. Vacuum the coils with the small brush attachment on your vacuum. Carefully place the teeth of the fin comb between the fins in the area above the warped fins. Slide the comb down through the damaged area to straighten the fins.