Kenmore microwave model 721-63252301 - no heat turns on - but nothing is getting hot

Yes, there is a thermostat device located on the magnetron. It will open up (turning off the magnetron) when it gets too hot, and it will reset automatically after it cools back down (in 5 to 15 minutes). The question is, Why is is over-heating? Usually it is caused by the exhaust fan being turned the wrong way. (For example, it may be set to exhaust the air out through the top of the microwave, but you don't have a vent there.) That fan can be turned to exhaust air out the top, out the back, or recirculate the air back through the front of microwave. It's easy to turn it around - the hard part is that you have to take the microwave down to be able to pull the fan out and rotate it the right direction.

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It sounds like you understand that the exhaust fan is SUPPOSED TO come on when the microwave oven gets hot when exposed to the heat of the range below it, since you mentioned that no burners are turned on. So in that case, I'm pretty sure that you have a bad fan thermostat. It's usually located behind the control panel on the bottom (inside bottom) of the microwave floor.

If you need further help, reach me via phone at https://www.6ya.com/expert/ronald_e6b9572cebe3ad27

Actually, that's a feature! If you cook much on the range (stove) beneath the microwave, the heat will cause the microwave bottom to heat up quite a bit (just touch it!), and the microwave will turn on it's exhaust fan in an attempt to save itself from burning up. It will shut off in about 15 minutes after you turn off the source of heat.
But if the fan comes on by itself even when the microwave is cool (or at least not hot), then you probably have a defective fan thermostat. This thermostat is located behind the control console on the inside bottom of the microwave.

If you need further help, reach me via phone at https://www.6ya.com/expert/ronald_e6b9572cebe3ad27

Actually, that's a feature! If you cook much on the range (stove) beneath the microwave, the heat will cause the microwave bottom to heat up quite a bit (just touch it!), and the microwave will turn on it's exhaust fan in an attempt to save itself from burning up. It will shut off in about 15 minutes after you turn off the source of heat.
But if the fan comes on by itself even when the microwave is cool (or at least not hot), then you probably have a defective fan thermostat. This thermostat is located behind the control console on the inside bottom of the microwave.

If you need further help, reach me via phone at https://www.6ya.com/expert/ronald_e6b9572cebe3ad27

bad magnetron... or a bad door switch check the door switches 1st

Hi,

Here is a tip that will help you to figure out what is wrong with your Microwave Oven....

Basic Microwave Oven Troubleshooting Tips

heatman101

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Hi,

Here is a tip that will help you to figure out what is wrong with your Microwave Oven....

Microwave Oven Basic Troubleshooting Tips

heatman101

chances are your magnatron quit on you and you may be better off getting a new one.

your problem might be more than a fuse chech the magnetron