Microwave starts running as soon as the door is shut, but not cooking?

This just happened to me. In my case, all I had to do was clean the door switch pieces on the door and inside and that allowed me to begin cooking again as normal. I'll keep an eye on it though because this is worrisome. This microwave isn't even 2 years old yet!

I replaced the door switch mounting block that was worn out and when I got it back together the same thing was happening to me. The cooling fan ran whenever I shut the door. Come to find out I didn't notice that the little lever that operates the bottom switch wasn't on the new part. So once I took it off the old block and put it on the new block problem solved

This issue is common amongst microwaves. The issue is within the control board. The main control board houses relays which have different functions. You can look at your wiring schematic and determine which relay (of I think 7 or 6) is the relay for power to cooling fan. Once you’ve located this relay, you can take an x-acto knife and cut the top completely off of this relay and you’ll see that the relay has fused together. Take a small flat head screw driver and pry the contacts apart and use a very small piece of sand paper to sand away any oxidized metal and reinstall control board. Unit should now function per manufacture specifications.

I was actually looking for an answer here. My microwave (same model) after 2 years runs as soon as I close the door (intermittently). It’s not actually activating the magnetron as nothing warms up. No table movement, no heat, and no counter/timing display. The microwave still lights the inside lamp, and the fan still blows. I have seen this over the last 20 or so years and normally this problem is due to the door switch microwaves (easy fix…unplug the system from line voltage first and ohm out the switch when it closes = if it doesn’t change resistance {open/closed} it’s always closed). I can’t duplicate the problem using a plastic device to test this theory when on, with the microswitch closed physically by the plastic pot. turner stick and system on. Looked like possible magnetic switch on face of door, or where these “bumps” hit on the inside of the microwave front plate (I used a magnet thinking it used a “reed switch”) but that had no effect. Hope I added some simple troubleshooting here but would like it if someone else had a better response for my problem. Thanks to all, that’s how we help each other !!

I had the same problem a few mins ago. Right after a major thunderstorm, even though microwave was unplugged. This is how I fixed it.

Unplug the plug from the electric outlet with caution, and very quickly plug it back in. It resets something inside the microwave with the sudden quick surge when u plug it back in very quickly.

Try it again - as I did -if it doesn't fix it completely the first time.

Exercise caution. Wear slippers, avoid contact with water.

Hey guys, i have been having the same issue with my microwave, where the the fan turns on as soon as the door shots. I read all the comments on what might be a potential cause of the problem and still couldn’t quite understand the problem. i found a potential fix while messing with mine, i have a standard 1200W cu whirlpool microwave, if you hold the cancel button for 3 secs it should lock the microwave even if the microwave door is open. And what that does is it prevents the microwave from being functional. you can close the door after you lock the micro wave and then hold for 3 secs to unlock. And that should stop the fan from turning on automatically after the the door shots. BUT my micro wave still couldn’t heat up my food after that trouble shooting. Try this out and let us know if yours heats up your food!! Thanks!!

My NEFF microwave as soon as I plug it in it will turn on the light and the turntable slowly moving without heating, in this time won’t start heating. I fixed it by levelling it up.

My Panasonic microwave displays 00:00 instead of 88:88 during startup and hence I'm not able to input commands..it as if its programming has reversed..can someone please help me

Post above referencing a relay on the control board. Chances are it’s fused closed. But if you tap on it with a screwdriver it may free itself up. Use a tester to see if it’s closed and ensure it has opened.

Hey gang, the light bulb seems to cause the problem with my sears unit

Update : WELL the lamp is not the trouble (new bulb = same trouble) But REMOVING the lamp, I can use the microwave ... I will need to study the Schematic Diagram... probably one on the boards connected to the Primary Interlock :-/

I had this problem. It is the main (usually the largest) relay on the control board. I ordered some after tapping on the relay and it started working again. Just waiting for it to quit again to replace the relay. DO NOT BUY from a parts place. They get about 100x more than they are worth. See AliExpress.

FIXED - Cost zero - Thank you all for your comments. My RCA low cost microwave table kept turning when door was closed and nothing else was working, no matter what button I pushed, I could not reset . I used a small Kid's dry paint brush and cleaned the holes (with microwave unplugged) (where the door things go when door is closed and plugged it back on and voila it is working like before . I am no tech so this is the solution I came up with and it works...

I can not unplug the microwave because it is built in with the oven. Can I still clean the holes with the end of a pant brush if is not unplugged?

Mine did that. I believe it was the main relay on the control board. Is yours a Whirlpool also? I tapped the relay and it started working again. The next time it failed I was ready with replacement relays.