A bathroom extractor fan that has stopped working has usually lost power (an isolator switched off, a blown fuse, a tripped breaker or a faulty pull cord or light switch), has a clogged or seized fan blade, or has a failed timer or humidity sensor. You can safely check the switches, the fuse and the consumer unit and clean the grille with the power off, but any work on the wiring in a bathroom should be left to a qualified electrician.

What is your fan doing?

Symptom	Most likely cause
Completely dead, no sound	No power: isolator, fuse, breaker, switch or pull cord
Hums but the blades do not turn	Seized motor bearings or blades jammed with dust
Runs, but steam hangs around and mirrors stay misted	Clogged grille or blades, blocked or crushed duct, stuck outside flap
Grinding, rattling or whining	Worn bearings, loose cover or blades catching
Runs all the time and will not switch off	Faulty timer or humidity sensor, or the sensor set too sensitive
Stops as soon as the light goes off	Timer overrun not set or failed, or a fan without a timer
Water dripping from the fan	Condensation running back down the duct
Cold draught through the fan when it is off	Backdraught shutter stuck open or missing

If you want it sorted rather than diagnosed, our electrical repairs and fault finding service covers extractor fans, and the phone is answered 24 hours a day, 7 days a week.

Check these first

These checks are safe for a homeowner. None of them involve opening up wiring.

1. The switch that runs it. Most bathroom fans come on with the light, from a pull cord or from their own switch. Check the light works. If a pull cord feels loose or does not click, the switch may have failed.
2. The isolator switch. Fans are normally wired through a local isolator that can switch off all the wires to the fan, often a small switch outside the bathroom, high on a wall or a ceiling pull. It is easy to knock off, or to leave off after decorating.
3. The fused spur. If the fan is on a fused spur, check it is switched on. If the fuse carrier looks out of place or the fuse has blown, a like-for-like replacement at the rating shown in the fan’s instructions is a simple job. If it blows again, stop.
4. The consumer unit. Look for a tripped breaker or RCD and reset it once. If it trips again, leave it off and call an electrician.
5. The tissue test. With the fan running, hold a single sheet of toilet tissue to the grille. A healthy fan will hold it in place. If it barely moves, air is not getting through.
6. Wait for the timer. Many fans have an overrun timer that keeps them going after the light goes off. If yours stops dead every time, the timer may be set to its minimum or may have failed.
7. Look at the outside vent, but only if you can see it safely from the ground. Leaves, nests and a stuck flap all block the airflow.

How to clean an extractor fan safely

Dust and fluff are the most common reason a working fan stops shifting air. Cleaning takes a few minutes.

1. Switch off the power at the consumer unit, not just the light switch.
2. Remove the front cover as the fan’s instructions describe. Most unclip or have one or two screws.
3. Wash the cover in warm soapy water and let it dry fully.
4. Brush the dust off the blades and around the opening with a soft brush or a vacuum brush attachment. Do not bend the blades.
5. Wipe the inlet and front face with a slightly damp cloth, as fan manufacturers recommend.
6. Refit the dry cover, restore the power and repeat the tissue test.

If the blades turn stiffly by hand, or the fan hums without spinning after cleaning, the motor bearings have probably worn. On most domestic fans the motor is not a separate part, so the answer is a new fan.

Common causes

Cause	What you might notice	Can you fix it yourself?	What the electrician does
Isolator or spur switched off	Fan dead, light works	Yes, switch it on	Nothing needed
Blown fuse	Fan dead, isolator on	Yes, once, like for like	Finds out why it blew
Faulty pull cord or switch	Cord loose, no click	No	Replaces the switch
Dust and fluff build-up	Weak airflow, fails tissue test	Yes, with the power off	Cleans or replaces the fan
Worn or seized motor	Humming, grinding, blades stiff	No	Replaces the fan
Failed timer or humidity sensor	Runs non-stop, or stops instantly	Adjust settings if the instructions allow	Tests the controls and replaces the fan or control
Blocked, crushed or detached duct	Fan runs but moves little air, damp loft	Only if safely reachable	Checks and reroutes the duct, insulates it
Condensation in the duct	Water dripping from the fan	No	Insulates the duct and sets a fall to the outside
Stuck backdraught shutter	Draught when off, poor extraction	No	Frees or replaces the shutter or grille

Why a working fan matters

A bathroom fan does more than clear the mirror. Moisture that is not extracted ends up as condensation on cold walls and ceilings, which feeds mould and damages paint, plaster and grout.

The Building Regulations guidance on ventilation (Approved Document F) sets a minimum intermittent extract rate of 15 litres per second for a bathroom. Where a bathroom has no openable window, the fan should keep running for at least 15 minutes after the room is left, which is why many fans have an adjustable overrun timer. When a fan is replaced, the new ventilation should not be worse than the old.

Repair or replace?

Most domestic extractor fans are sealed units. When the motor fails, the sensible repair is a new fan, and it is a chance to fit a quieter model or one with a humidity sensor or timer if the old one did not have them.

• Replacing a fan like for like is usually a straightforward job.
• Adding a fan where there was none, running a new circuit, or altering circuits near a bath or shower can be notifiable work under Part P of the Building Regulations. In England, circuit alterations in the spaces around baths and showers are notifiable, and a registered electrician deals with the certification.

Our guide to choosing an electrician in Hertfordshire explains what to look for. If the fan is part of a bigger problem, such as a leaking shower or failed seals, our bathroom repairs team can look at that on the same visit.

What it costs with Vantage

In normal working hours there is no call-out fee. After the first hour, time is charged in half-hour steps, and parts, including a replacement fan, are quoted before we fit them. Evening, weekend and overnight visits are charged at the out-of-hours rates. Every rate is published on our prices page, so you know what you will pay before we arrive.

Frequently asked questions

How do I reset a bathroom extractor fan?

Most fans do not have a reset button. Switching the power off at the isolator or consumer unit for a minute and back on restarts any built-in timer or humidity sensor. If the fan still will not run, the fault is the fan, its controls or the supply.

Why is my bathroom fan running all the time?

A humidity-sensing fan will keep running while the room is damp, so it may just be doing its job, or the sensor may be set too sensitive. If it never stops, even in a dry room, the sensor or timer has probably failed. Some fans also run continuously at a low speed by design, so check the instructions.

Why is water dripping from my extractor fan?

Warm, moist air cools as it passes through the duct, especially an uninsulated duct running through a cold loft. The condensation runs back to the fan and drips out. The fix is an insulated duct laid to fall towards the outside.

Do you need an electrician to replace a bathroom extractor fan?

We would always recommend one. The fan is in a bathroom, which is a special location for electrical safety, and the new fan must be wired with a suitable isolator and the right fuse. Anything beyond a like-for-like swap may also need certifying under Part P.

Does a bathroom need an extractor fan by law?

For new bathrooms and new homes, the Building Regulations require extract ventilation that meets the rates in Approved Document F. In an existing bathroom, work you carry out should not leave the ventilation worse than it was. A working fan is the simplest way to keep condensation and mould under control.

Help in Hertfordshire, Bedfordshire and Cambridgeshire

If your fan is dead after these checks, keeps blowing its fuse, or needs replacing, our electricians can find the fault and fit a new fan safely. Book through our electrical repairs and fault finding page or call 01462 506374.