The reasons listed below when the microwave extractor fan is not working are listed from most likely to least likely. Check or test each cause, starting with the most probable cause:
Exhaust fan motor
Main control board
To determine if the fan exhaust motor is defective, remove it from the microwave and try manually rotating the fan blades. If the blades do not rotate freely, replace it. If the fan blades rotate freely, then use a multimeter to check the motor for input power and continuity. If the motor receives current but does not run, replace it. If the motor is not continuous, replace it.
The thermostat monitors the air temperature and turns on the fan if necessary. If the thermostat is defective, it will not turn on the exhaust fan at all. Use a multimeter to check the continuity of the thermostat. If the thermostat is not continuous, replace it.
The main control board may be defective, but this is rare. Before replacing the control board, first check the exhaust fan motor and wiring. If the exhaust fan motor is not receiving power, the main control board may be defective. If you need help with high-quality microwave repair, call us right now!