How To Fix A Microwave Fan That Isn't Working - Microwave Repair

How To Repair A Microwave Exhaust Fan

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About this repair:

  • Rated as REALLY EASY
  • 48 repair stories
  • 4 step by step videos

Charcoal Filter

If the exhaust fan on your over-the-range microwave is not working, the problem may simply be the charcoal filter. The charcoal filter is used to trap and absorb cooking smells when no external vent system is used. Over time, the charcoal filter will become clogged and restrict the air flow. The charcoal filter is normally located behind the exhaust air outlet grill. You can typically detach the grill by removing some retaining screws and then remove and replace the charcoal filter which may also have a spring clip to hold it in place. Replace the charcoal filter on a regular basis to maintain a good airflow. You should also check the condition of the primary grease filter as well.

Grease Filter

If the exhaust fan on your over-the-range microwave is not working, the problem may simply be the grease filter. The grease filter or filters are used to trap cooking oils and fats to prevent contamination of the exhaust system. With normal use, the grease filters will become clogged and restrict the air flow. Normally, the grease filters are located on the bottom of the microwave and are held in place with spring clips or tabs for easy removal. Regular cleaning of the grease filters in hot water and detergent will help maintain proper airflow, however, if the filters are very dirty or damaged they should be replaced. If an external exhaust system is not used, you should also inspect the internal charcoal filter.

Damper Assembly

If the exhaust fan on your over-the-range microwave does not appear to be working, the problem may be with the damper assembly. If you are connected to an external exhaust system, the damper is used to prevent unwanted outside air from entering the room. The damper is basically a metal or plastic flapper that closes off the exhaust duct when the fan is not running, and opens when the fan turns on. The damper may have a spring assisted flapper or it may rely on gravity to keep it closed when the fan is not in use. If the damper does not open easily or completely, then the airflow may not be sufficient to remove steam or cooking smells. The damper is located at the exhaust outlet of the microwave and removal from the wall or cabinets may be necessary. Verify that no foreign objects or the exhaust duct connector are interfering with the damper. Replace the damper if it appears to be damaged or does not open and close easily. When re-installing the vent connector, make sure there is no interference with the damper.

Fan Motor

If the exhaust fan on your over-the-range microwave does not appear to be working, the problem may be with the fan motor. The fan motor is located at the top rear of the microwave and exhausts the air into the duct system or re-circulates into the room through the charcoal filter depending on the installation. If the fan motor does not turn on when selected, you will need to disconnect the power and remove the unit from the wall or cabinet to service. Remove the cover and locate the fan motor. Rotate the motor by hand. If the motor will not turn, it needs to be replaced. If the motor turns freely, you can check the motor for continuity with a multi-meter and if no continuity is found, you will need to replace the motor. If the motor does show continuity, the next step would be to check for power to the fan motor. This is a live voltage test and should only be performed by a qualified person. If the correct voltage is available, then the motor is likely defective. If no voltage is detected, the problem may be with the wiring or the electronic control board.

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