Original post by: Al Seaver ,
I received a microwave to repair and resell a few months ago with the identical problem. Everything worked except that it refused to heat, so the problem was obviously not the ceramic fuse(s) hidden inside microwave ovens. I removed the outer cover, shorted the super capacitor so I wouldn't get zapped, and proceeded to investigate. I did go ahead and check the fuse just for the heck of it, but if it had been blown the microwave would have been totally dead. No lights, no nuthin'. I noticed that there were 3 micro safety switches on the door latch assembly. Upon testing each, I discovered that the top two were working just fine, but the third one at the bottom was not working. I proceeded to replace it with a like switch that I had salvaged from another appliance, tested the oven, and it has since worked perfectly.