Appears magnetron fan not working.it over heats and shuts down after running for awhile. after cooling panel says rest and it appears to work ok but fan dosn't sound like it is running

Some ovens have a thermal protector on the magnetron. It opens if the magnetron gets too warm. Or, sometimes they will open at too low of a temperature. Another possibility is that air flow to the magnetron for cooling is bein restricted, or the cooling fan is defective.

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most likely it doesn't have. operation is time controlled (per your setting, in sec or min.) typically it has a or more than one thermal cutout/s (you can call it thermostat too, depending on how you define it) which will temporarily opens the circuit to prevent overheating then should re-set (turn on again) if not defective.

see the steps and use the common sense:
God bless you
All microwaves have some sort of a cooling fan to help keep the magnetron and controls at a tolerable level. Most OTR models will usually use the vent motor for the cooling fan also. Countertop units have a small fan behind the control panel somewhere. Either way, if the cooling fan is not working and heat builds up, it is going to open a thermostat. On some makes, this thermostat might re-set itself as soon as the temperature cools down. Other makes, you will have to replace the thermostat or fuse.
If this is your microwave oven repair problem, you will need to check the operation of the fan. Below in the component testing chart, you will see how to test the fan. Also, if possible, make sure the fan is not obstructed somehow and not turning. Also check your fan relay at your control board for voltage, if no voltage, replace control board. This fan should come on at the same time any cooking starts.

If the cooling fan is not working, that would explain the shutdown problem. The function of the fan is to cool the magnetron down when it is warming or cooking the food, if the fan fails to run, the thermal fuse will detect heat rise causing a shutdown with in 5 seconds or more, the clicking suggest fan issues. I would recommend a whirlpool technician to go through the system.

The cooling fan protects the magnetron from overheating when it is running, the magnetron has probably been damaged and has shorted due to the excessive heat that they generate and blown the main fuse in the microwave to stop any further damage. The repairs for parts and labor will not be justified and replacement in the long run will be cheaper.

It indicates the magnetron is getting to hot "that heats the food" when that happens the thermal fuse opens to protect the magnetron from over heating and shuts it down and waits until it is cooler before it resets. The other problem could be the fan not working or not properly that blows on the magnetron, it helps keeps the temperature regulated so it can run hard. If it turns out the fan is fine, then the magnetron is slowly breaking down until it becomes unusable, which means it will need to be replaced "pricey" or buy new "probably cheaper"

this is the control board that is failing and it can be ordered , if it were the magnetron then it would just not heat up the food
the control board is resetting when the microwave is started because of a faulty chip on the board

You absolutely need the magnetron cooling fan to be working, or the magnetron will be destroyed!

It is part # 3511800100 and you can order it for less than $20 here.

Far less than a magnetron.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

If the fan comes on when you put the unit into a cook cycle and all sounds normal otherwise, you most likely have a bad magnetron tube. (Google "GE magnetron failure" and watch how many complaints and articles pop up). The tube overheats and trips the thermal relay causing the unit to shut off until it cools back down and comes on.
Very, very common problem on these models although GE will not admit it.

It sounds just like the magnetron is bad, overheating and opening the thermostat. This is how it would work if that were the case.

 

One other thing is to be sure that the cooling fan is running and that you feel air flow.

 

You should check the air filter and grille, as well as the outside vent for any blockage.

 

If you or a friend decide to work on it, we have *critical* safety, disassembly, and troubleshooting info at our site, which is linked at our listing here on FixYa: http://tinyurl.com/yzjozk

 

You can find helpful exploded view diagrams and order parts by entering your model number here: http://tinyurl.com/gv383