Will everything run, except heat, if you have a faulty door switch?
I have a Maytag Microwave, Model # MMV1174DS-1, which is appears identical to a Whirlpool. Everything appears to run on the microwave (fan, lights, turntable, sounds fine) except it doesn't heat anything. I replaced the diode yesterday. I tried it again after the diode replacement and nothing changed. However, the microwave heated up the water one time when I used the cook-Food Item #-Quantity sequence instead of just a timed cook. I thought I was on to something but I could not get it to heat again after about 15-20 more tries. So, I am thinking maybe it is a door switch that clicked just right, because if it was a high-current failure (diode, capacitor, or magnetron) the microwave would be able to heat after the part failure, right? Would a faulty door switch allow a microwave to run normally with the exception of producing heat?
"Most Maytag / Whirpool microwaves have either 3 or 4 door switches which are connected to mechanical cams driven by the door latches. With the use of cams, the switches are made to activate in a particular time sequence (one after another in rapid succession) to indicate to the control board that the door latch process is ""successful"". This feature is called a safety interlock, and it's design requires > 1 switch to prevent improper operation of the magnetron in case a single door switch sticks in the closed position.
Often the plastic cams or switches simply wear out (prematurely worn-out cams are often are caused by frequent door slamming), and the interlock stops working. In this case, the magnetron will no longer turn on (so, no heat), but the light and turntable will still work perfectly fine.
Replacement cams will run ~$35 (best case)."