A bathroom exhaust fan that has stopped working almost always falls into one of three categories: no power reaching the unit, a motor that has seized or burned out, or a fan that spins fine but cannot actually move air because the duct is blocked. A simple tissue test at the grille tells you immediately whether you are dealing with the third category before you open anything up.
The tissue test: is it actually pulling air?
Hold a single sheet of toilet tissue near the fan grille while it is running. If it is pulled toward the grille and held there, the fan is genuinely extracting air and any complaint (moisture, odor) points elsewhere. If the tissue barely moves, the fan is running without actually venting — this points to a duct blockage rather than the fan or motor itself.
Check for power first
- Check the wall switch and breaker
A tripped breaker or a GFCI outlet on the same circuit (common in bathrooms) can cut power to the fan without affecting the lights.
- Check the connection inside the fan housing
Most fans have a plug running from the motor to a receptacle inside the housing — this can work loose over years of vibration and use.
- Confirm the fan is not on a separate switch than expected
Some installations wire the fan to a different switch than the light, which can look like a dead fan when only the light switch was tried.
A blocked or disconnected duct
This is the most common cause of a fan that runs but does not actually ventilate the room. Lint, dust and general debris accumulate inside bathroom duct runs gradually over years, and a duct that has come loose at a joint can leak the air right back into the wall or attic cavity instead of outside. If the tissue test above showed weak airflow, this — not the fan itself — is the most likely cause.
Seized or burned-out motor
| Symptom | Likely cause |
|---|---|
| Fan makes no sound at all, no movement | No power reaching it, or a fully burned-out motor |
| Fan hums but blades do not turn | Seized motor bearings — moisture exposure over years is the usual cause |
| Fan runs, but quieter/weaker than it used to | Aging motor losing power, or a partially blocked duct |
Bathroom fan motors run in a persistently humid environment, and that moisture exposure is exactly what causes bearings to seize or windings to eventually burn out. A motor confirmed to be receiving power but not turning at all generally needs replacement rather than repair.
Check the switch itself
A worn wall switch can fail independently of the fan and duct entirely. If you have access to a second known-working switch or can test with a multimeter, swapping or testing the switch is a low-cost thing to rule out before assuming the fan unit itself has failed.
When to call an electrician
If power is confirmed reaching the fan (tested at the housing, not just at the switch) but the motor still will not run at all, the fan unit itself needs replacement. This is a straightforward job for an electrician, particularly since bathroom fans are often tied into shared wiring with the light fixture.
