Microwave did not heat so I replaced a cracked magnetron and diode. Still didn't heat (but all other functions working fine). I found a bad thermostat fuse and replaced it. It now heats, but as soon as I plugged it in this time after replacing the thermo-fuse, the hood vent exhaust fan turned on. The touch pad only lets me toggle from high to medium exhaust and skips low and off. I also noticed the light that illuminates the stovetop below only toggles from high to nite light to off, but skips medium light. All other touchpad funtions operate as normal. I appreciate any ideas you can give me. Thank you.

This is from two years ago, so I can't remember what I did, but I got the fan to be able to turn off and on with the right number of speeds (and I was wrong about the light....there is no medium light). Anyway, the microwave would not heat UNLESS I turn on the exhaust fan. I couldn't figure it out, so I installed it back on the wall and now for the last two years we just have to turn on the exhaust fan for the microwave to heat. No fan, no heat. It's a slight annoyance, but we're otherwise glad it works now after having to replace the magnetron.