Fan runs when door is closed - no heat

SOMETIMES A DOOR SWITCH GOES BAD AND BACK FEEDS POWER THAT RUNS THE FAN AND IF IT HAS IT SOMETIMES THE TURNTABLE TOO SO YOU HEAR THE FAN RUN ALL THE TIME BUT TYPICALLY IT IS NOT HEATING. YOU COULD PUT A SMALL CUP OF WATER INSIDE TO SEE IF IT IS HEATING, PROBABLY BAD DOOR SWITCHES OR BAD CONTROLLER.

Faulty door switch.

Door switch error. DO NOT USE like this.

see this causes and fix it. God bless you
Magnetron If the microwave is loud or noisy only when cooking, the magnetron tube might be defective. The magnetron uses high voltage, high current DC power to generate the microwave frequency that cooks the food. Under normal circumstances the magnetron is nearly silent. However if it is damaged or nearly burned out it can begin emitting high pitched or growling noises. It's not normally dangerous to use a microwave oven when it makes these noises, but they are an indication that the magnetron is almost dead and will need to be replaced.
Exhaust Fan Motor If the microwave is loud when running the fan motor might be
Stirrer Motor If the microwave is loud or noisy the stirrer motor might be worn out. The stirrer is a metal blade which slowly turns around, deflecting the microwave energy in a random pattern inside the microwave oven. As the motor nears the end of its useful life it begins to make grinding noises. The microwave will not heat food evenly without this stirrer, the motor should be replaced.
Turntable Motor If the microwave is loud or noisy the turntable motor might be worn out. This is a common problem and relatively easy to replace.

Key clue is table does not move---All microwaves with a table have a lever switch that is engaged when door closes--only can get at from inside the unit----it prevents the unit from operation if door not closed.

What happens from closing door a lot is the switch with a lever arm can come loose or even if snapped into a plastic holder break out of the holder.

IF this it is not too expensive a repair.

THere are three possibilities, open magnetron "heats food" cracked high voltage diode, or a shorted high voltage capacitor.

Our microwave in office won't shut off. It continues to heat and fan is running as soon as we close the door. Tried everything, unplugged, canceled everything. Please let me know what to do.

Hello :

This happens because of a bad door switch . The plastic mounts inside the microwave which hold the door switches and onto which the door latches lock when you close the door .

Check also the turntable . It could be out of it's right place .

WARNING :

1:Don't slam your microwave door because this may cause the fuse to blow and this is the reason of bad door switch problem .
2: A microwave is capable of giving you a serious electrical shock even when it's unplugged , so I recommend you to call a repair technician for help .

please don't forget to rate .

good luck .

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The door interlock may be faulty.