How to Fix / Troubleshooting

Safety First: Unplug the microwave or switch off the breaker before servicing the exhaust system.

Check controls: Test all fan speed settings. Note which speeds work and which do not.
Inspect filters and vents: Clean or replace grease filters and ensure exterior vent flaps are not stuck.
Access blower: Remove the top grille and access the exhaust blower motor and wheel. Check for obstructions and ensure the wheel spins freely.
Test motor: Use a multimeter to test the motor windings for continuity. Replace the motor if open or seized.
Speed control: If the motor is good but some speeds do not work, the fan speed switch or control board relay may be faulty and require replacement.

Microwave exhaust fan on over-the-range JennAir unit does not run or only works on some speeds.

Possible Causes