Fix a noisy or weak bathroom exhaust fan
A bathroom fan that rattles, hums or barely pulls air is often just dirty: lint and dust clog the grille and coat the blower wheel. Cleaning it, with the power off, fixes a lot of weak and noisy fans. If it's still loud or weak afterward, the damper, the duct or the motor is the next place to look. A fan that's doing its job should hold a single square of toilet paper against the grille, which makes for a handy before-and-after test.
How a bathroom fan moves air
A bathroom fan pulls damp air through the grille, past a small blower wheel, and out through a duct to a vent on the roof or an outside wall. A flap called a damper opens as the air pushes out and closes to keep outside air from coming back in.
Dust matted onto the wheel throws it off balance and slows it down, which is why dirty fans rattle and move less air. A crushed duct or a stuck damper does the same thing, even with a clean fan.
Why fans get loud or weak
It throws the wheel off balance and cuts airflow.
Lint blocks the air coming in.
The flap can't open to let air out.
Air can't get out easily.
Worn bearings hum, squeal or slow down.
| What you notice | Likely cause | What to check |
|---|---|---|
| Rattles or buzzes | Dust on the wheel, or loose parts | Clean it; tighten the screws. |
| Hums but barely spins | Worn or gummed-up motor bearings | Clean it; if it still drags, replace the motor. |
| Runs, but steam doesn't clear | Clogged grille, damper or duct | Clean it; check the damper and duct. |
| Doesn't run at all | Breaker, switch or motor | Check the power; call an electrician. |
Clean and quiet the fan, step by step
- Turn off the powerSwitch the fan off at the wall, then turn off its breaker. Don't rely on the wall switch alone before reaching into the housing.
- Take off the grillePull the grille down gently. Most are held by two spring clips; squeeze them together to release it. Wash the grille in warm soapy water and let it dry.
- Clean the fanVacuum the housing and brush the dust off the blower wheel blades. If the motor plugs into a receptacle inside the housing, unplug it and lift the fan assembly out; it's easier to clean on a table.
- Check the damperLook where the fan connects to the duct. The small flap should swing open freely; clear any lint or debris holding it shut.
- Put it back and testReinstall everything, restore power and run the fan. Hold a single square of toilet paper up to the grille; a working fan should hold it there.
Watch it done
- The fan runs without rattling
- The duct damper flap swings open freely
- A single square of toilet paper stays held against the grille
Still rattling or weak? Check the wheel for wobble, then the duct.
If it's still loud or weak
If it still rattles, tighten the grille and housing screws and check whether the wheel wobbles. A wobbling wheel or a squealing motor usually means a replacement motor, which many makers sell by model number.
If airflow is still weak, check the duct for crushed or disconnected sections, and the outside vent for a stuck flap or a nest. A fan that vents into the attic rather than outdoors should be rerouted by a pro.
What a pro typically charges (a rough estimate; prices vary by area): An electrician typically charges $150–$400 to replace a bathroom fan motor or the whole fan.
Find an electrician near you