Why does my microwave not heat up food?

joshua, for the longest time the consensus on iFixit is to replace the whole unit. Microwave ovens generate high voltages and dangerous amounts of radio-frequency radiation. Attempting to repair one is NOT for the amateur. I advise recycling it and getting a new one. On the flipside of this, you may just give us the serial number and we can try to find a common simple problem, but anything above that, you should leave to a professional.

I received a microwave to repair and resell a few months ago with the identical problem. Everything worked except that it refused to heat, so the problem was obviously not the ceramic fuse(s) hidden inside microwave ovens. I removed the outer cover, shorted the super capacitor so I wouldn't get zapped, and proceeded to investigate. I did go ahead and check the fuse just for the heck of it, but if it had been blown the microwave would have been totally dead. No lights, no nuthin'. I noticed that there were 3 micro safety switches on the door latch assembly. Upon testing each, I discovered that the top two were working just fine, but the third one at the bottom was not working. I proceeded to replace it with a like switch that I had salvaged from another appliance, tested the oven, and it has since worked perfectly.

"@Nancy Perez ,

You need to check that the door interlock switches are OK.

There are 3 of them part 41,42 &43.

They are the safety switches on the oven to ensure that the door is properly closed when the oven is started.

Do all testing with the oven totally disconnected from the power.

Even then it is not safe as the HV capacitor needs to be discharged correctly as it has enough power (>6000V) stored in it to either seriously injure or even kill you. This power can stay there for weeks so disconnecting the mains supply is not enough.

Also the “common” method of discharging the capacitor by placing a screwdriver across the terminals may not be too safe either as you need to use an appropriately sized driver. One too small can result in it literally welding across the terminals and possibly causing flash burns in the process.

The safest way is to use a 10M Ohm 10W resistor and use a lead and clips to connect it between the +ve terminal of the capacitor and the oven chassis to discharge the capacitor. This takes a 5-10 minutes and then short circuit the capacitor terminals to make doubly sure that it has fully discharged, but people are impatient and try to take the short way out

Microwave ovens are extremely dangerous if you don’t know what you’re doing. Call an expert instead."

"I hired a repairman who told me the same thing. Too expensive to repair....just buy a new one....is this the only solution? Isn't there enough waste? The oven was manufactured in 2006!

Jim T."

"i have kenmore elite microwave

i change already the fuse but cannot heat what is the problem"

My Kenmore model 790.80333310 microwave stopped heating food. Before I went out and bought another, I unplugged it from the wall outlet for 15-20 seconds and then tried it with ¼ cup of water for 1 minute. It boiled the water. Not sure why, but it did work.