I have a run-of-the-mill GE microwave oven that goes completely powerless for about 3-5 minutes after each use, indiscriminately whether the use is for a single second or many minutes. While shut down, the microwave appears to be completely dead, as neither the door light, the LCD display, nor the keypad work. When the microwave reemerges from shutdown, the clock must be reset which indicates that there was a total shutdown without any persistence. How do I diagnose this issue?

  • 2
    Turn off the breaker, remove the receptacle and check for loose wires and/or push in connections. Tighten screws. Repeat for any other receptacles/lights/switches on the same breaker. After this if the problem remains, it might be the microwave.
    – crip659
    Dec 19, 2023 at 23:08
  • 3
    If it's a 120V microwave, move it to another outlet on a different circuit for a quick test.
    – JACK
    Dec 20, 2023 at 0:06

1 Answer 1


Of course check to make sure there isn't a problem with the circuit supplying the microwave first.

What I suspect is actually going on here though is a problem with one of the thermal cutout switches. There's typically two of these: one for the magnetron and one for the cooking chamber. These are the only devices in the microwave that can both interrupt power to the control electronics and reset themselves. One of your thermal switches is probably false triggering.

If you're comfortable with electronics repair, you may be able to follow the electrical diagram located in the service manual or on the inside of the case to determine which switch is triggering. Since it's after only a second or two, it's quite unlikely to be an actual overtemperature situation.

If there is any chance you're not comfortable with working around high voltage, just replace the unit. Microwaves are quite capable of killing you dead once the cover is off.

  • One of your thermal switches is probably false triggering. Be aware that it might not be a false trigger and that something may be overheating (perhaps a loose wire is overheating) and that there may be an actual problem causing a thermal shutdown. Otherwise, +1.
    – FreeMan
    Dec 20, 2023 at 13:29
  • I considered that, but the possibility of it triggering after a single second and then working for several minutes the next time makes me think it's quite unlikely to be a loose wire. I suspect one of the thermal limit switches actually has a bad connection internally, so it's triggering itself occasionally.
    – KMJ
    Dec 20, 2023 at 16:25
  • A loose wire could be wiggled by the vibrations of the microwave, especially the motor spinning the turntable. Some runs could leave the wire more firmly connected than others. Also, my microwave's turntable runs in opposite directions each time I turn it on (why, I have no idea). It's possible that it stops immediately every other run based on turntable direction and the OP just hasn't noticed...
    – FreeMan
    Dec 20, 2023 at 16:27
  • How straightforward is the process of diagnosing the thermal switches?
    – trndjc
    Dec 20, 2023 at 17:43
  • repairfaq.org/sam/micfaq.htm has you covered there. Make sure to read the section on safety. I quote: Microwave ovens are probably the most dangerous of consumer appliances to service. Very high voltages at potentially very high currents are present when operating - deadly combination. These dangers do not go away even when unplugged as there is an energy storage device - a high voltage capacitor - that can retain a dangerous charge for a long time.
    – KMJ
    Dec 20, 2023 at 17:52

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