Is my microwave possessed?

Three years old, no issues before yesterday. Doesn’t happen every time. Put item to be nuked inside microwave and shut door. Before you can push a button, the light comes on, and the turntable starts rotating. There’s no fan or anything: it’s silent. And it keeps going until you open and close the door, when it stops and light goes out. There’s no setting that allows the microwave to do this.

What would cause a microwave to do this? Do I need a repairman or an exorcist?

Likely a short in some wiring or bad soldering on a circuit board. I wouldn’t pay to have it repaired as that’s likely to cost as much as just buying a new one.

If it were me, I’d open it up and see if I could track down and fix the problem (yes, caps, transformers, lots of danger, I know).

It shouldn’t be too hard to diagnose if you have a working knowledge of electricity and a multimeter.
A quick fix would be to either disconnect the turntable or just leave the door open when not in use. If you go with the latter, I’d remove the light bulb because it would annoy me to have it on all the time.

Just for kicks, you might try picking it up an inch or so and dropping it. Not hard enough to damage anything, but maybe rattle a wire or sensor into a place that’s not cause a short.

I’ve had that happen, when you sorta half-way click the door shut in the wrong way.

Try boiling some holy water and see what happens.

Slam the door hardish a coupla times. Or smudge it with sage.
Either should work equally well.
Then go to Walmart and buy a new red one.

Hmm. All good suggestions. I should have mentioned I live in an apartment complex, and the microwave belongs to it, not me. Also, it’s built-n. under-cabinet microwave. I also should have said that a firm click to close the door doesn’t prevent its dizzy behavior.

I was kind of hoping there might be a simple fix even I, the Electric Idiot, could do, or maybe that someone could tell me I’d inadvertently switched it to a secret “Light and Rotate only” mode. But it sounds like it’s going to need professional help.

If you rent and the microwave belongs to the landlord, they should repair or replace it.

I’ve heard that under-the-counter microwaves are often quite expensive, and may be worth their while to fix it.

In that case, let the manager know. They’ll likely just drop a new one it and take that one out. Why are you considering calling (and paying) someone to repair it when it’s not even yours?

I REALLY screwed up the OP. I meant to say call the maintenance man, not the repairman. The maintenance guy is very slow here, and I suspect it’ll be a couple of weeks before he’d get here. Add in the time for parts or the new microwave to arrive, and another two weeks for him to come around and fix it, and, like I said, I was hoping for an explanation of what’s going on (which I now have, thanks to you, Joey P.) and maybe an easy fix I could do so I wouldn’t have to wait for the maintenance guy…

My apologies for that OP. Yikes.

While the OP is not likely to try to attempt a repair, I want to caution people that there’s a good sized capacitor in microwaves that might hold a charge. So care must be taken that you don’t touch anything conductive inside until you discharge that cap.

One thing to try is to unplug it, wait, and plug it back in. Given the type this might be hard to do, but check it out anyway. (And if unplugging is not doable, then DIY repair is even more “fun”. Finding and shutting off the right breaker and all that.)

Also, safety wise, the door interlock/power system is designed to prevent the microwave from operating if the door is not completely closed. There seems to be a problem going on related to this. I would suggest not using the microwave until it is fixed.

In mine, the condition is reproducable–almost close the door, but hold it in place just before you would normally hear the click of the door locking, and it starts up.

Is there an ominous voice that says: “Zuul” when you open the microwave?

If so, you know who to call.

This used to happen to my old TV set.

That microwave needs to be sent to a stud farm, to live out its golden age in happiness. And by stud farm, I mean a recycling depot.