Question about Microwave Ovens
may be the fuse, which is usually located behind the grille, on
floor of the oven behind the control panel, between the door switches,
or on a filter board near where the cord comes into the unit.
If the fuse is good, it may be an open thermostat or thermal cutout (TCO) / thermal fuse on or near the magnetron or on top of the cavity / body of the oven.
If it goes dead for a while during or after cooking then comes back on, the magnetron is probably overheating and causing the magnetron thermostat to open.
Then when it cools, it closes the circuit and allows power through again.
When checking TCOs or thermostats, if it has a hood fan thermostat, that should read open, as opposed to the others, which should read closed.
So don't let that fool you.
If the cavity thermostat needs to be checked or replaced you'll need to pull the oven from the wall.
If so, the installation instructions are very handy, and it's best to have two people since the microwave can be heavy and awkward.
You can download Whirlpool owner's manuals and installation instructions here.
If it went dead almost immediately after pressing the Start pad, that's usually a shorted high-voltage capacitor.
If it went dead a few seconds after pressing the Start pad, that's usually a failing high-voltage transformer.
If it goes dead or blows the breaker (or GFI) when you plug it in or open or close the door, then there's a problem with a door switch or door switch mount.
If it's intermittent or random, it may be a bad connection, usually on the control board or a loose fuse holder, or even an intermittent fuse.
You should do a continuity test on the fuse while it's in the holder (with the microwave unplugged, of course) then turn the fuse by hand or take it out and put it back in, then test it again.
If you remove the fuse, then press the meter leads against the ends, it can allow internal contact to be made and make a bad fuse appear to be good.
If you or someone you know decide to look into it, we have critical safety information and disassembly information at our site, and our link is at our listing here on FixYa.
There should also be a "mini-manual" hidden inside the unit behind the control panel or hidden on the left side behind the grille, which is very helpful when troubleshooting & testing.
If you don't find yours, or if you want to look at it without disassembling the oven, you can download it here.
At our Web site, we have a video available showing how to remove a typical over the range control panel assembly in under 5 minutes.
You can usually find helpful exploded view diagrams and order parts by entering your full model number here.
We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.
Posted on Dec 25, 2008
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Posted on Jan 02, 2017
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