# Microwave starts when lift door



## RAL238 (May 20, 2018)

There are one or more switches that sense when the door is closed. Either your door has become misaligned and it not activating the switch properly, or the switch itself is going bad.


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## huesmann (Aug 18, 2011)

Yep. Here's an example:










They have little plungers, like the nub you can see near the A4315B number. Part of the door latch contacts that plunger and depresses it, so the microwave knows the door is closed. If the latch is misaligned, or the switch is loose, it can malfunction. The little plastic clamps and pins that hold the switch in place can break as the plastic ages and gets brittle.


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## kah5683 (Sep 18, 2010)

microwave built in 2017. Hard to believe due to old age. Maybe slamming door shut?


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## Fix'n it (Mar 12, 2012)

does the door look out of alignment when its closed ?


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## JIMMIEM (Nov 17, 2016)

The switches that the others have mentioned are continuity switches. They are very easy to test and replace and cost under $20. There is also a spring inside the front door panel that works with the latch, which might be involved. There are videos available and you can probably find specific directions for your model. But, microwaves can be deadly so there is understandable hesitation about giving fixit info.
An inexpensive multi meter will perform continuity testing.
Also, if you decide to give it a go be gentle as a lot of the clips holding things together are usually plastic and easily broken.


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## huesmann (Aug 18, 2011)

kah5683 said:


> microwave built in 2017. Hard to believe due to old age. Maybe slamming door shut?


Slamming the door shut can definitely break the latch mechanism so that it's no longer in the correct alignment. Both of these issues can easily be inspected if you're handy with a screwdriver and a strong plastic pry tool (the latter is to disassemble the door frame to access the latch).


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## kah5683 (Sep 18, 2010)

I check microwave again. Setting aside that it may be (and probably is) the switch(s)...


Take a look at the pics below. The door isn't slanted or crooked. If I lift up at the hinge (on with the label), it lifts the whole door.


Is there a way to adjust this up?


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## huesmann (Aug 18, 2011)

Well, that is typically how you remove the door. It rotates on pins; you're just sliding the door up and down on those pins.


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## kah5683 (Sep 18, 2010)

so there is no way to adjust up in hinge area?


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## huesmann (Aug 18, 2011)

I mean, a little bit, like you could jam a spacer in there to lift it some. Whether that would be enough to make it work—who knows? Are you handy enough to disassemble the door?


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## kah5683 (Sep 18, 2010)

I could open the door. I know it is probably a switch. How do you test switch with multimeter? I've also read about the insane level of electricity that flows through the microwave - want to make sure I know how to avoid that issue.


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## JIMMIEM (Nov 17, 2016)

kah5683 said:


> I could open the door. I know it is probably a switch. How do you test switch with multimeter? I've also read about the insane level of electricity that flows through the microwave - want to make sure I know how to avoid that issue.


The multi meter will have directions. You will be testing the switches for continuity. Some of the switches should have continuity when the switch is open and some should have it when the switch is closed. Each switch will have a diagram on it which will indicate when it should have continuity. There are leads on the switch which are connected to wiring. There is a metal arm inside the switch which will touch the leads depending upon its state. The state will be either open or closed depending on it's purpose. The multimeter leads will be touched to the switch leads and will show continuity when the switch is opened or closed. Continuity shows whether current can flow from one lead and through the switch and out the other lead. The metal arm creates the continuity path. If the switch is defective it won't close or open the metal arm when it should.
The dangerous part is the high voltage capacitor which stores energy to power the microwave.......this is discharged by unplugging the microwave and then shorting out the capacitor, which will discharge it.


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## huesmann (Aug 18, 2011)

Here's some more testing info, and videos:
https://www.partselect.com/Microwave+test-door-switch+repair.htm









I actually had a microwave with a door switch that the internal contacts were _fused_ together in the off position, so it wouldn't run.


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