How to Fix / Troubleshooting

Safety: Unplug the microwave before accessing the fan.

Check controls: Try all fan speed settings. If none work, suspect power or motor. If only one speed works, suspect the control or speed circuit.
Access fan motor: Remove the top grille and, if necessary, lower the microwave to access the blower assembly.
Inspect blower wheel: Look for grease buildup or foreign objects preventing rotation. Clean thoroughly.
Test motor: With a meter, check continuity of the fan motor windings. Replace the motor if open or seized.
Control board: If the motor is good but does not receive power on any speed, the control board or fan relay may be defective.

Over-the-range microwave vent fan does not run or runs only on one speed

Possible Causes