HI ,
My Jenn Air over-the-range microwave is just out of the one year warranty, and the microwave will not heat. Everything else works fine! The convection oven, lamps, ventilation fan, display, and timers, turntable etc all work normal. Microwave does nothing to a glass of water 5 minutes. I did some inspections inside. The primary and secondary resistance of high voltage transformer are nominal. The high voltage capacitor is not shorted and seems to take a charge. The high voltage diode conducts in one direction but not the other. The filament resistance of the magnetron is nominal and has infinite resitance to ground. The primary, secondary and monitor switches which engage/disengage with the door are correctly conducting or not. The thermostats seemed to be working although the documentation is confusing me (Bottom therm and MGT seem to be the same thing).
I was wondering if the power relay and control board was working - I listened carefully at power 50% mode and could clearly hear the 16 second on and 14 off cycling of the power relay.
So I am pretty sure it is a bad magnetron. It isn't obvious how to replace the magnetron and a call to Whirlpool told me they would not send me a magnetron because "Only certified technicians are allowed to do this work for fear of radiation exposure if it was installed incorrectly. Please call the store that you bought it from to get service. Only the parts are under warranty not the labor."
Any help would be useful.
Thanks
Paul

I have had many customers get free mags up to 5 years from date of purchase. But they need to call and ask for it.