How to get my microwave oven to heat again

April 11, 2009 6:17 AM

Why did my microwave oven stop heating after I tried to use it to heat water in a clear pyrex measuring cup? And how can I get it to work again? I've had the not-heating problem before, and it has gone away. I can't remember whether I did something to make it work again. This time, I tried unplugging the oven and plugging it in again -- no dice. Everything works except for the heating up part.
posted by Sia Stewart to home & garden (5 comments total)

I have had something like this happen before: a fuse was blown.
posted by aroberge at 6:59 AM on April 11

Heating water in a pyrex in and of itself wouldn't be the cause (I've been doing this every day for a few years). How old is the microwave? You might have blown your magnetron which, if it's a fairly inexpensive microwave (<$100) means it's not worth the cost of repair.
posted by zerokey at 7:30 AM on April 11

The intermittentness of this problem means your door switches (there are two to four) aren't being triggered properly. This can cause a fuse to blow. You can try giving the door a wiggle up and down but it really needs adjustment. Probably not worth getting done in most cases.
posted by Mitheral at 7:48 AM on April 11

Is it running at all? (I.e. is the fan/deflector running and making the usual sounds?) Generally the door switches keep anything from working, at least on the microwaves I've had break on me. Although I guess it's possible that it could be designed so that the door switch cuts off just the magnetron but not everything else, I've never seen that.

If it's not a "disposable" microwave, it shouldn't cost you more than the very minimum service charge at an appliance-repair place to diagnose. It'll probably either end up being a cheap repair not much more than the cost of the diagnostic, or it'll be prohibitive and you'll need to replace the whole unit.

If you want to try to DIY here is a extensive FAQ on microwave repair, but I'd advise you not to do this unless you are very comfortable working on HV systems. You can seriously zap yourself working inside a microwave; along with big CRTs they're one of the things I generally don't truck with unless I'm 99% sure I know exactly what to do.
posted by Kadin2048 at 9:37 AM on April 11

Thanks, everyone. I don't think it's a fuse, because everything else works. The magnetron sounds like the likely culprit. I will take it to a repair shop for a diagnosis. I'm not going to mess with it myself.
posted by Sia Stewart at 8:26 PM on April 11