Fixed: Loud noise (buzz/rattle/vibration) in window air conditioner


Premium Member
Apr 13, 2010
Brookline, MA
Model Number
6-10 years
SUMMARY: Loud buzz, even with front cover removed. Fix: wedging a toothpick under the loose lower-right corner of the evaporator.

I had a loud, intermittent, buzz/vibration from my LG-brand window A/C. Removing the entire plastic front panel, the buzz continued, and could be made to start or stop with pressure against the evaporator or the plastic housing/divider.

After an hour or two of tinkering, to no avail, here's how (I think) I finally fixed it:
I noticed that the evaporator was secured only at the top and bottom-left corners. Pressing a finger against the right edge, I could wiggle it back and forth, and be rewarded by a thump or click that sounded like (a sample of) that annoying buzz.

Awed by the carelessness of LG's design, I wedged a toothpick between the right-side bottom of the evaporator, and the plastic tray underneath it. The evaporator could not be shaken, and the unit no longer emits that maddeningly loud (disposal-like) grinding buzz.

Other fixes that I doubt made any difference, but maybe they'll work for you. With the unit out of its case:
* Tightening every screw, slight tightening of compressor hold-down bolts,
* wedging a wood shim under the two otherwise-loose tabs on the back of the bracket, atop the unit, that secures the front evaporator casing to the rear fan housing,
* gently (!) bending copper loops away from the compressor and from the unit's metal floor, and
* reducing the pitch, so that the back of the unit was 1/2-inch lower than the front (per LG's instructions)


Appliance Tech - Moderator
Staff member
Jul 11, 2006
Murray, Utah 84107, United States
After 5 years, it seems the rubber grommets under the compressor and fan motor, if it uses them, start to get hard from the heat of the compressor. I found that was usually where the vibration starts. Sometimes WD40 will soften them, but not always.