Microwave exhaust fan not working

When your microwave exhaust fan is not working, start with the door switch, the most likely cause. A defective door switch or micro switch may fail to tell the control board that the door is closed, preventing the fan from operating. Test each switch for continuity with a multimeter and replace any switch that fails. Next, check the exhaust fan motor. The blades should turn freely by hand. If they do not, replace the motor; if they turn freely, test the motor for incoming voltage and continuity. A failed microwave thermostat can also keep the fan from turning on, so test it for continuity and replace it if open. If the microwave fan is running but the vent is not pulling air, inspect the grille for clogs or damage. The control module is less common, but it may be faulty if the motor is not receiving power after the switches, motor, thermostat, and wiring check out. Enter your model number to find the exact replacement part for your microwave. Any repair requiring removal of the outer cabinet must be handled carefully because the high-voltage capacitor stores lethal charge even after the microwave is unplugged. Proper capacitor discharge is required before interior work, so use a qualified technician if you are unfamiliar with the procedure.

01 - Microwave Exhaust Fan Motor

To determine if the fan motor is defective, remove the fan motor from the microwave and try turning the fan blades by hand. If the blades do not turn freely, replace the fan motor. If the fan blades do turn freely, use a multimeter to test the motor for incoming power and for continuity. If the motor has power but won’t run, replace it. If the motor does not have continuity, replace it.

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02 - Microwave Door Switch

A defective door switch may not signal the control board that the door is closed, which can prevent the button that controls the exhaust fan from functioning. To determine if any of the door switches are defective, use a multimeter to test each of the switches for continuity. If any of the door switches do not have continuity, the switch or switches should be replaced.

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03 - Microwave Thermostat

The thermostat monitors the air temperature and turns on the fan when necessary. If the thermostat is defective, it won’t turn on the exhaust fan at all. Use a multimeter to test the thermostat for continuity. If the thermostat does not have continuity, replace it.

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04 - Microwave Grille

A damaged or clogged grille can prevent the air from being properly exhausted when the exhaust fan is turned on. Confirm the grille is free of obstruction and, if the grille is visibly damaged, replace the component with a new one.

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Highly Likely

05 - Microwave Micro Switch

A defective micro switch may not signal the control board that the door is closed, which can prevent the button that controls the exhaust fan from functioning. To determine if any of the micro switches are defective, use a multimeter to test each of the switches for continuity. If any of the switches do not have continuity, the switch or switches should be replaced.

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Common

06 - Microwave Control Module

If the microwave exhaust fan is not working, the control module might be defective. However, this is not usually the case. Before replacing the control module, first check the exhaust fan motor and wiring. If the exhaust fan motor is not getting power, the control module might be at fault and require replacement.

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Common

07 - Microwave Main Control Board

The main control board might be defective. However, this is not usually the case. Before replacing the control board, first check the exhaust fan motor and wiring. If the exhaust fan motor is not getting power, the main control board might be at fault.

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Common