Author Topic: Interlock Switch on Frigidaire Microwave Keeps Failing?!  (Read 1515 times)

Offline bio132

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Model PLMB209DCC

About 8 months ago, my microwave stopped cooking, but the timer counted down fine. Research here helped me quickly suspect a faulty interlock switch. We also figured out that if we lightly pressed the "open" button, the microwave worked fine. In testing the switch (photo attached), I found that with the plunger depressed completely, the switch didn't work correctly, but if I let the plunger out slightly, it was fine. I ordered a replacement switch and since I'd need to wait a bit for it to arrive I ground some plastic off the plunger on the existing switch. This allowed the switch to function normally (with the door closed, the plunger was at rest slightly less depressed than normal). The switch opens again when the plunger is released a little more - so it still retains the safety functionality of ensuring the door is closed.

The CRAZY FREAKING THING I CAN'T FIGURE OUT: I've gone through 3 replacement switches that all develop the same exact problem after a couple of months. The third one just did it. I can now slightly press the "Open" button and make it work, but I need to order yet another replacement switch. Any ideas as to why this switch keeps failing? Could I really have such bad luck that I'd get 3 new bad switches?

I ordered the first one from a guy on Amazon. The second two came from Mouser. Here's the part number:

Omron

653-D3V-16G-3C25
D3V-16G-3C25
MINIATURE BASIC

Any help is appreciated!!


Offline keithvibe

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Re: Interlock Switch on Frigidaire Microwave Keeps Failing?!
« Reply #1 on: July 13, 2014, 08:34:16 PM »
if the switches keep failing and you say you put light pressure on the door switch I would go after the latch itself.

Offline bio132

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Re: Interlock Switch on Frigidaire Microwave Keeps Failing?!
« Reply #2 on: July 14, 2014, 11:31:21 AM »
Are you thinking the latch is causing the switch to fail? The switches actually go "bad". A new switch works correctly with my multi-meter. When I push in the plunger (little button on the switch) completely, the circuit is closed. After a couple of months in my microwave if I push it in completely, the circuit is open. I have to let it out maybe .5mm for the circuit to close. Could the latch be causing something to happen that would mess up the switch? Like the door closing too far and pushing the plunger in too far and misaligning something in the switch?

Offline keithvibe

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Re: Interlock Switch on Frigidaire Microwave Keeps Failing?!
« Reply #3 on: July 14, 2014, 06:46:02 PM »
Just thinking out loud. If you keep getting the same part to fail need to consider other things other than that part. Could be the latch, could be something like the board. Could try getting different manufactured switches.

Online wildimaginations

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Re: Interlock Switch on Frigidaire Microwave Keeps Failing?!
« Reply #4 on: July 15, 2014, 03:20:44 AM »
Get an amp meter and measure how high amps are running through that switch.  If it's excessively high, you'll need to find out why.  Could be a magnetron or hv diode going out.  Could be a high draw through the transformer.  Any number of things could be wrong.
Appliance Service Technician
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About 45 mins east of San Francisco

Offline bio132

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Re: Interlock Switch on Frigidaire Microwave Keeps Failing?!
« Reply #5 on: July 19, 2014, 04:09:10 PM »
Ooooh. Good tip! I replaced it again. The previous post got me thinking that perhaps it is something mechanical. I grinded down the plunger a bit with a dremel so it wouldn't be depressed quite as far (maybe it was bottoming out and getting out of alignment). If it goes out again, I'll be back in a couple of months to let you know  ::)


If I need to replace it, I'll definitely get a read on the amps through the switch.


Thanks!

Offline bio132

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OK, the switch is failing again. How do I test the amps through the switch? I have a fluke multimeter, I know how to switch it to amps, but where do I test? It seems like if I put a lead on each side of the switch, all the amps will go through the switch, not through the multimeter. I know this has to be easy - any pointers would be appreciated. Thanks!!

Online wildimaginations

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About 45 mins east of San Francisco

 

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