How to Fix a Microwave Exhaust Fan – Microwave Repair
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How to Fix a Microwave Fan That's Not Working

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Charcoal Filter

If your microwave exhaust fan stopped working, the issue may be a clogged charcoal filter. This type of filter is used in over-the-range microwaves, to absorb smells and pollutants from heating food. These pollutants will build up over time and cause the filter to become clogged. Make replacing the charcoal filter on your microwave a regular part of your home maintenance routine.

How to inspect a microwave charcoal filter:

  1. This is a very simple inspection. For most models no tools will be needed, however, some models may require a screwdriver to access the filter.
  2. The charcoal filter is usually located behind the exhaust air outlet grill. Remove the grill in order to access the filter. The method for removing the grill varies between models, refer to your owner’s manual to determine how to remove the grill for your model.
  3. Remove the filter in order to visually inspect it for any signs of built-up debris or damage.
  4. If your filter is damaged, clogged, or if it has been longer than the manufacturer’s replacement guidelines, you will need a replacement charcoal filter.

Grease Filter

If your microwave exhaust fan has stopped working, it may be because the grease filter is clogged. The grease filter traps oils and fats from the food that is being heated, to keep the exhaust system clear. It is common for grease filters to become clogged over time and need replacing.

How to inspect a microwave grease filter:

  1. This is a very simple inspection; you should not need tools to complete it.
  2. Grease filters are typically located at the bottom of the microwave and are held in place with spring clips. Locate and remove your grease filter in order to inspect it.
  3. Looking for any signs of damage or debris, visually inspect your grease filter. You can clean your grease filter with soap and water, although it may need to be replaced entirely if the buildup is too stubborn to clean.
  4. If your filter is damaged or is still clogged after cleaning it, you will need a replacement grease filter.

Damper Assembly

If your microwave exhaust fan is no longer working, the damper assembly may be causing the problem. The damper is a component in over-the-range microwaves that prevents exterior air from entering through the exhaust system. The damper is a flap made of metal or plastic which seals the exhaust duct when the fan is off and opens when the exhaust fan is running. The flap is often spring-loaded or may be designed so that it simply opens and closes relying on gravity.

How to inspect a microwave damper assembly:

  1. Disconnect your microwave from the power supply before beginning.
  2. Depending on your model, you may need to remove the microwave from its place in the wall and may need to remove all or part of the microwave’s cabinet to access the damper assembly.
  3. Check for any objects that could be keeping the damper from opening and closing. You should also visually inspect the damper for any signs of wear, cracking, or damage.
  4. If you identify any issues during your inspection, you will need a replacement damper assembly.

Fan Motor

The exhaust fan on your microwave may not be working because of an issue with the fan motor. This part is a component of over-the-range microwaves and helps circulate the air through the exhaust system.

How to test a microwave fan motor with a multimeter:

  1. Begin by unplugging your microwave and removing it from the wall.
  2. The fan motor is usually located in the back of the microwave, near the top. Remove the fan motor cover and try rotating the motor manually. If the fan does turn, remove it from the appliance to test it using a multi-meter.
  3. With your multimeter set to Rx1, touch the motor’s terminals with the probes to test for continuity. You should receive a reading of 0, indicating that there is continuity.
  4. If the fan does not turn in step 2, or if your fan does not have continuity, you may need a replacement fan motor.

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