Range Hood Fan Not Working? Start With Power, Then the Switch
Quick answer
A hood fan that does nothing at all is usually power or the switch. A fan that hums but will not spin is usually the capacitor or a seized motor. A fan that works on some speeds but not others is almost always the switch. The light still working tells you power reaches the hood.
When a range hood fan stops, the useful question is not whether the motor has failed but whether it is being asked to run at all. Hoods are wired through a switch that carries the full fan current and clicks thousands of times over its life, and that switch fails far more often than the motor behind it. A few observations from the kitchen floor will tell you which half of the hood the fault is in, before anyone opens anything.
1. Does the light still work?
This is the single most useful check and it takes a second. On almost every hood the light and the fan are fed from the same supply and separated only after the switch. If the light works, mains power is reaching the hood and the fault is in the fan side: the fan switch, the wiring after it, the capacitor, or the motor. If neither the light nor the fan works, the problem is upstream — a tripped breaker, a GFCI outlet, or the connection in the cabinet above.
2. Test the speeds against each other
Run through every fan speed in turn and note exactly which do nothing. A multi-speed hood switch has a separate set of contacts for each speed, and they wear one at a time. If high works but low does not, or the reverse, the motor is fine by definition — it is running on at least one setting — and the switch is failing. That single test rules out the most expensive part on the hood, which is worth doing before any part is ordered.
3. A switch that feels loose or clicks without doing anything
Rocker and rotary hood switches wear mechanically as well as electrically. A switch that has become loose in its housing, rocks further than it used to, or clicks without the fan responding is telling you the internal contacts are no longer meeting even though the mechanism still moves. It feels like something is loose and needs tightening, but the movement is a symptom rather than the fault. Grease that has worked into the switch body from years of cooking above it accelerates this, which is why hood switches age faster than switches anywhere else in a kitchen.
4. A motor that hums but does not turn
If the fan hums, buzzes, or gets warm without spinning, the motor is being powered but cannot start. Two things cause it. Many hood motors use a start capacitor, and a failed capacitor leaves exactly this symptom — power present, no rotation. Or the motor bearings have seized, often after years of grease and heat. There is a rough field test: with power switched off at the breaker, see whether the blower wheel turns freely by hand. A wheel that spins freely with a humming motor points at the capacitor; one that is stiff or will not move points at the motor or a jammed wheel.
5. Grease on the blower wheel
A hood pulls cooking vapour through itself for years, and the blower wheel collects a layer of hardened grease that adds weight and can bind it against the housing. This shows up as a fan that starts slowly, struggles, or stops under its own load. It is also the cause most often mistaken for a dying motor. Filters that have not been degreased in a long time make it worse, because everything the filter misses lands on the wheel behind it. Cleaning the filters properly is worth doing regardless of what the fault turns out to be.
6. When the fan runs but the kitchen still fills with smoke
If the motor spins at full speed and the hood still does not clear the air, this is not a fan fault at all and the checks above will not help. That is a venting problem — a blocked duct, a stuck exterior damper, a recirculating hood with exhausted charcoal filters, or a duct run that is too long or too narrow. Our guide on a range hood not venting covers that separately, because the fix has nothing to do with the motor or the switch.
When to Call a Specialist
A range hood sits directly above a cooking surface and is wired into a mains circuit, often hardwired rather than plugged in, and frequently above a gas range. Switch, capacitor, and motor work all mean opening a live-wired appliance overhead, so this is not the place for improvisation: switch the circuit off at the breaker before removing any panel, and if the hood is hardwired, hand it over. Call us straight away if you smell burning, see scorching around the switch, or the breaker trips when the fan is selected. Built-in and luxury hoods commonly use model-specific switches and control boards that are not generic parts.
Frequently Asked Questions
The light works but the fan does nothing. What does that tell you?
It tells you power is reaching the hood, which rules out the breaker, the outlet, and the supply wiring in one step. The fault is after the switch: most often the fan side of the switch itself, sometimes the capacitor or the motor. It is the most useful single observation you can make, and it is worth mentioning when you call because it narrows the visit before we arrive.
Is a hood fan that hums always a dead motor?
No, and it is worth checking before assuming the worst. A hum means the motor is being powered but cannot start turning, and on many hoods that is a failed start capacitor rather than the motor — a much smaller part. A blower wheel jammed by hardened grease produces the same symptom. The motor is the least likely of the three and the most expensive, so it should be the last one concluded, not the first.
Only the high speed works. Is that worth fixing?
Yes, and it is usually a straightforward repair. A speed that has stopped working while others still run means the contacts for that speed inside the switch have failed, and the motor is proven good by the fact that it still runs on another setting. Replacing the switch restores every speed. Left alone, the remaining speeds tend to follow the first one over the following months.
My hood is a built-in luxury model. Does that change anything?
It changes the parts rather than the diagnosis. The checks on this page apply to any hood. What differs is that built-in and professional hoods often use a model-specific switch, control board, or motor assembly rather than a generic part, so identifying the exact model matters before anything is ordered. We diagnose first and give you a firm price before any work begins.
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