Symptoms
- Rattling or buzzing during operation
- Noise changes with fan speed
- Vibration felt through the wall or sill
- Grinding or squealing sound
Likely causes
- CommonLoose front panel, grille, or mounting screwsVibration works screws loose over a season of use.
- CommonUnit not seated firmly in the window frameGaps let the whole unit vibrate against the sash and sill.
- PossibleDebris or ice contacting the fan bladeLeaves or built-up frost can cause a repetitive clicking or scraping noise.
- PossibleWorn fan motor bearingsProduces a grinding or squealing noise that gets worse over time.
- Less commonBent fan bladeCauses a rhythmic thumping tied to fan speed.
What to do
- Turn off and unplug the unit before inspecting it.
- Tighten the front grille, side panels, and any visible mounting screws.
- Check that the unit sits securely and levelly in the window frame with no gaps at the sides.
- Add or replace foam weatherstripping around the sides if the frame fit is loose.
- Remove the front cover and filter and look for leaves, ice, or debris near the fan blade.
- Plug it back in and listen: a steady grinding or squealing that follows fan speed suggests a worn motor rather than a loose part.
Tools and parts
- Screwdriver
- Flashlight
When to call a pro
Call an appliance technician if the noise is a persistent grinding or squealing from the motor, since fan motor bearings aren't practical to service yourself.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.