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Bathroom extractor fan not working?
Dead, humming, weak or won’t switch off: the quick checks, the common causes, and the extraction you need to stop damp and mould.
A bathroom extractor fan that has stopped, hums without spinning, or won’t switch off is a common fault. Left unfixed, it means steam stays in the room, and that means damp and mould.
Quick checks
- The fan isolator. Most fans have a small switch outside the bathroom, often high on the wall or near the light switch, so they can be isolated for cleaning. Check it’s on.
- The fuse board. Check the lighting circuit or fan circuit hasn’t tripped.
- How it’s controlled. Many fans run with the light and keep running for a few minutes after (an overrun timer). Some only start when humidity rises. It may be working as set.
- Clean the grille. Switch off at the isolator first. A clogged grille and fan cuts the airflow dramatically.
Common causes
| Symptom | Likely cause |
|---|---|
| Completely dead | Isolator off, tripped circuit, failed motor or a wiring fault |
| Hums but doesn’t spin | Seized bearings or a failed motor |
| Runs but barely pulls air | Blocked grille, ducting or outside vent; crushed or very long ducting |
| Won’t switch off | Overrun timer or humidity setting, or a faulty humidistat |
| Noisy or rattling | Worn bearings, loose fixing, or a backdraught shutter flapping |
Most bathroom fans are cheap to replace, and a like-for-like swap is usually quicker than a repair. If the fan is in the shower area, it must be rated for that position, and usually low-voltage (SELV) or suitably protected. We’ll fit the right one.
Damp, mould and how much extraction you need
The Building Regulations (Approved Document F) set extract rates: 15 litres per second for a bathroom, and 30 l/s for a kitchen with a cooker hood (60 l/s if the fan is elsewhere in the room). Many older fans and long duct runs don’t achieve it. If you have mould on the ceiling, the fan may be working but too weak.
Landlords: damp and mould is a hazard your tenants can report, and social landlords now have strict timescales to investigate and fix it. Working extraction is one of the simplest fixes; see electricians for landlords.
A recent fan call-out in St Albans
On Monday 19 October 2026 a customer in St Albans called us because their extractor fan had stopped working. It was an inline fan, fitted in the loft and ducted to the room below, so nothing could be seen from inside the house.
- Same day: we went out that day, checked the supply to the fan at its fused spur and confirmed the fan itself had failed.
- One visit: from the description on the phone we had already picked up a replacement 150mm inline fan on the way, so it was fitted, connected and tested there and then.
- Simple bill: one hour’s labour plus the cost of the fan. No second visit and no waiting for parts.
See the full job: what we found, what we fitted and photos.
If your fan has gone quiet, tell us what kind it is (ceiling, wall or a fan up in the loft) and, if you can, send a photo. It often means we can bring the right part first time. Call 01727 238 999; our phones are answered 7am to 10pm, seven days a week.
Questions we’re asked
Why has my bathroom extractor fan stopped working?
Check the fan isolator switch outside the bathroom and the fuse board first. If they are fine, the motor has usually failed or seized, and the fan needs replacing.
Why does my extractor fan keep running?
Most bathroom fans have an overrun timer that keeps them going for a few minutes after the light goes off, and some start on humidity. A fan that never stops usually has a faulty timer or humidistat.
Is it worth repairing an extractor fan?
Rarely. Most domestic fans cost less to replace than to repair, and a new one is often quieter and more powerful.
Do I need an electrician to replace a bathroom fan?
It is mains electrical work in a bathroom, so use a competent electrician. A like-for-like replacement is not notifiable; a new circuit would be.
Why is there mould even though my fan works?
The fan may be too weak for the room, the ducting too long or blocked, or it may not run long enough after a shower. Approved Document F expects 15 litres per second in a bathroom.
Written by SEGplc. Last updated 19 October 2026.
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