Why Has the Extractor Fan Stopped Working? Common Causes & Fixes

You flip the switch, and silence. No hum, no whoosh of air, just a dead piece of plastic on your ceiling or wall. It’s frustrating, especially if you’ve got a steamy shower waiting to turn your bathroom into a sauna. But before you call a handyman or rip the whole unit out, pause. Most extractor fan failures come down to three things: power issues, mechanical blockages, or component burnout. You can diagnose and often fix these yourself in under an hour with basic tools.

The Power Supply Check

Start with the boring stuff because it’s usually the culprit. If your fan doesn’t even twitch when you hit the switch, don’t assume the motor is dead. First, check your home’s electrical panel. A tripped circuit breaker or a blown fuse is common, especially if the fan shares a line with other high-draw appliances like hair dryers or heaters. Reset the breaker; if it trips again immediately, you have a short circuit that needs professional attention.

If the breaker is fine, look at the switch itself. In older homes, wall switches wear out. The internal contacts corrode or break, stopping electricity from reaching the fan. You can test this by bypassing the switch temporarily (with power off!) or using a multimeter. If power reaches the fan housing but the fan stays silent, the issue moves deeper into the unit.

Blocked Ducts and Grilles

Sometimes the fan works, but it sounds like it’s straining against a brick wall. This is usually due to blockage. Over time, dust, lint, and humidity build up inside the ducting. If the duct is crushed behind a wall or clogged with debris, the motor overheats and shuts down as a safety measure.

• Check the exterior vent: Go outside. Is the flap stuck shut by bird nests or paint?
• Inspect the grille: Remove the cover indoors. Vacuum the blades and the mesh filter.
• Test airflow: Hold a tissue near the intake while the fan runs. If it barely sticks, your duct is blocked.

In New Zealand, where humidity is high, condensation inside metal ducts can cause rust and collapse. Flexible foil ducts are notorious for sagging and trapping water. If you suspect this, replace the flexible section with rigid PVC pipe for better durability.

Capacitor Failure: The Silent Killer

If your fan hums loudly but the blades won’t spin, or they spin slowly until you give them a nudge, you’re likely dealing with a bad capacitor. This small cylindrical component gives the motor the initial jolt of energy to start spinning. They fail frequently due to heat and age.

Replacing a capacitor costs about $10-$20 NZD and takes ten minutes. Always discharge the old capacitor carefully (it holds charge) and match the microfarad (µF) rating exactly. If you’re unsure, take the old part to an electrical supply store.

Motor Burnout and Bearing Wear

If the capacitor checks out, the motor might be toast. Motors fail for two main reasons: bearing seizure or winding burnout. Bearings rely on lubrication. In dusty environments, oil dries up, causing friction. You’ll hear grinding or squealing noises before total failure. Once seized, the motor draws excessive current and burns out the windings.

Smell the motor housing. A sharp, acrid odor indicates burnt insulation. At this point, repair isn’t worth it. Replacement motors exist, but labor costs often exceed the price of a new fan. For most standard ceiling units, buying a new model is more economical than sourcing a specific replacement motor.

Thermal Cut-Out Trips

Modern fans have built-in safety features called thermal cut-outs. These sensors monitor temperature. If the motor gets too hot-due to blockage, bad bearings, or continuous overuse-the sensor cuts power to prevent fire. Let the fan cool down for 30 minutes. If it restarts, you had a temporary overload. Investigate why it overheated. If it happens repeatedly, clean the vents or replace the unit.

When to Call a Professional

Do you need an electrician? Yes, if:

• You find burnt wiring or melted insulation.
• The circuit breaker trips repeatedly.
• You’re uncomfortable working with live wires.
• The fan is hardwired without a plug access point.

In Wellington, damp conditions accelerate corrosion. If your fan is in a wet area without proper IP rating (Ingress Protection), moisture ingress is a real risk. Ensure any replacement has an IP44 rating or higher for bathroom use.

Preventative Maintenance Tips

You don’t want to repeat this headache next year. Here’s how to keep your fan running:

1. Clean quarterly: Vacuum the grille and blades every three months.
2. Run it longer: Keep the fan on for 15-20 minutes after showering to clear residual moisture.
3. Check seals: Ensure the external vent flap opens freely. Grease hinges if stiff.
4. Avoid painting over vents: Paint blocks airflow and traps heat.