The microwave has a base thermostat which is a safety device.
Exhaust fan on microwave won t shut off.
The exhaust fan will turn on automatically during heavy use of the surface burners on the cook top if the fan thermostat senses too mush heat.
When it senses heat it turns on the exhaust fan.
Fridgidaire microwave will not turn off check the fan.
On several models of microwaves the thermostat is super sensitive causing the exhaust to run longer than needed.
If you are cooking on the cooktop it can sense the heat and the fan won t turn off until the thermostat cools.
It cannot be turned off manually.
When the microwave gets hot the thermostat closes.
If pushing the stop button does not turn off your microwave try opening the door while it is still.
Thus turning the fan on will keep the electronic control board from getting too hot.
The exhaust fan thermostat is usually the failed component.
When it cools down enough it will shut off.