Repair and disassembly guides for Kenmore Microwaves.

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Why does microwave oven fan turn on erratic

i have disconnect oven from outlet wait for a few reconnect turn on fan and it will run continously want turn off why?

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3 Answers

Chosen Solution

Exhaust Fan Motor

If the exhaust fan does not run the fan motor might be bad. Remove the fan motor from the microwave oven and see if the blades can be turned by hand. They should turn very freely, if they're stiff the fan motor will need to be replaced. The fan motor can also burn out. To test this use an Ohm meter. The motor should have continuity. If it doesn't, replace it.


If the microwave exhaust fan is not working the thermostat might be defective. The thermostat senses the air temperature and turns on the fan as needed, if it's defective it won't turn on the fan. Watch our video on testing thermostats.

Main Control Board

If the microwave exhaust fan is not working check the exhaust fan motor and wiring. If they are good the main control board might be defective.

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The question was about a fan that doesn't shut off. It runs continuously. It doesn't have a problem staying on. The only way to shut it off is to unplug the microwave oven. William Frazier wants to know: How do you get it to stop running?

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Fan thermostat switch senses high temps and to protect circuit board, will turn on the

Fan. It is annoying to hear that mother turn on and I don’t give a $@$* if I need to replace $220 micro a bit prematurely—I just disconnected the switch and everything else is fine with no annoying fan turning on when I’m cooking on Christmas Day!!

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