I hane a Galaxy over the range microwave model # 721.80002401. The problem is the fan randomly turns on and will not go off unless I unplug it.

You probably have a bad fan thermostat. This thermostat is supposed to turn on the vent fan if the microwave oven gets too hot (caused by cooking too much or having too many burners turned on on the range beneath the microwave oven). It should shut off in about 15 minutes after your turn off the range burners. But if it comes on for no reason, or won't turn off, then You probably have a bad fan thermostat.

If you need further help, reach me via phone at https://www.6ya.com/expert/ronald_e6b9572cebe3ad27

the low fan relay on the circuit board is faulty

mine turned exhaust fan on automatically... i couldnt shut it off... had to unplug it.... no buttons worked.

I would check the door switches for a faulty switch. If it were condensation on the control panel. I would think it would have dried out by now unless it has damaged the control board.

I regularly see (and repair) this light and / or fan failure on model JVM1660SB005 and most any model of over the range microwave.
The problem is on the controller assembly, which I regularly repair very affordably.

At my Web site, you can get details, plus I have a video available showing how to remove a typical over the range control panel assembly in under 5 minutes.

This light failure often occurs when a bulb goes out and the filament shorts, or when the bulbs are removed or installed without first unplugging the oven from the power line. Either can cause such a failure on the controller.

The lights can can be inoperable or stuck on or stuck in "night light" mode. Sometimes this will similarly affect the fan operation or inside light, too.

For more free DIY and other help & advice, feel free to contact me via my site.

Please include FULL model number*, FCC ID number*, + detailed symptom information. ( * on the tag in cooking cavity or around door frame or control frame or on back)

William E. Miller, AS-EET
http://www.microwavecontrol.com
Microwave Oven Control Panel Repair Nationwide
"Recycling by repairing since 1982"

Sounds like you have a shorted fan motor. Disconnect the power going to the fan and then try turning the microwave on again. Do not run the microwave for more than 5 or 6 seconds without the fan operating. If this does not cure your problem then the next most likely problem is either the AC Capacitor (silver can), or the Magnatron (4 inch square silver unit with cooling fins and thick wires. The voltage present on these two units can hold a charge in excess of 5000 volts, even after a time it is unpluged. Don't go near these unless you know what you are doing.

Best of luck.

Board needs to be replaced

My Kenmore microwave oven fan has been turning on and off, almost every hour. Sometimes 3 or 4 times in one hour. It's very random. Model No. 721-80593401 Serial No.503TA03208
Please help!!!

my microwave oven have inside a a metal papel i remove becouse sparks when turn on .this pece of paper is necesari
thanks
alexas