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    From Jeff's site: http://www.applianceaid.com/component-testing.php

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FFMV1645TS tripping circuit breaker then fuses


Premium Member
Mar 28, 2023
Model Number
1-5 years
My three year old Frigidaire FFMV1645TS microwave began tripping its breaker about six months ago, sporadically. I'd reset the breaker and it would run fine, up till last week. Last week the fuse blew. thinking it might be door realted, i checked all three of my door switches on a DVM and all three tested perfect (two NC and one NO). So put another fuse in on Saturday morning, used it a few times, and it blew again today (while running). so it is no longer throwing the breaker, but now is blowing the fuse fully and always, while running.

What things should I check?
Sounds like switches. The switches may test good but timing is off. The latch and holder will wear slightly out of tolerance and cause a mistiming of the switches. The switch holder, switches and latch should be replaced. This occurs often when opening the door while it’s running.

This should fit yours: Latch 5304522899
It’s not blowing the fuse when opening the door while it’s running. It’s just blowing the fuse during running (no opening door).
I understand. I have the same microwave and it would blow the breaker not internal fuse. It was the switch latch and holder. Mine is a 2016 model. Other than that, your magnetron could be failing.
Mine had been tripping the breaker for the last six months but two weeks ago it blew the fuse.
Internal fuse blowing is likely the monitor interlock switch sticking.
Thanks @Wx4usa for helping him, this is the monitor switch:

There's a good video of it here: https://www.repairclinic.com/PartDetail/Micro-Switch/5304509459/4583655
Internal fuse blowing is likely the monitor interlock switch sticking.
But why the circuit breaker for six months and now the fuse? And it never tripped or blew fuse on startup or when trying to open the door while it was running. It only tripped breaker (and lately, blew fuse) while just running.
Without being on site to check it personally, I cannot tell you. All I can say is sometimes the house breaker is weaker than the internal fuse. It happens. I work on a lot of these microwaves and see it quite a bit. As I said in an earlier post, it happened to my personal unit within the last 30 days. It was throwing the home breaker not the internal fuse. Replaced the holder and all three switches and it’s not recurred. I’d sure try replacing the latch, holder and all 3 switches first and see if it rectifies the issue. If not it’s likely pulling too much current with a failing capacitor or magnetron. Then it’s decision time. May not be worth repairing.
Thanks WX4USA. It’s at my sons and unfortunately given his distance I can’t help him as much either since this is an intermittent failure. I’ve replaced a few diodes and electrolytics on microwaves but never had these switch issues. Next time I’m there will replace with the kit you suggested. Suppose I could just put in a cap for good measure (pita take off mount) but after that I’m not putting more money in it. Frigidaire appliances are builders choices for one reason.

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