Over range microwave fan not working

Microwave Repair
1

about 3 years ago I bought the over range microwave oven from a large warehouse open box sales extravaganza, took it home and tested it, everything was fine and the fan started, worked on both speeds, no problem

so, I installed it with the back draft damper off and the exhaust duct rising straight up through the upper floor and through the roof

the fan still worked, but seemed to start slow sometimes

I “built-in” the unit and now, when all is done, the fan tries to start but won’t

if I reach down into the top of the unit where the duct comes up, out of the wall cabinet bottom and spin the fan, just to get it going, it works fine; but shut it off and try to start it again, it won’t

it makes a soft whirring (or buzzing) sound like it’s trying to start, but can’t quite get up the power to start to spin, spinning it by hand (or little wire) gets the squirrels exercising

what’s wrong?

I would have to destroy the wall cabinet, back splash tile and part of a wall to get it out to disassemble it, more work and expense than the unit was worth

2

What is the complete model number of the microwave?

Gene.

3

I don’t know how that could be the issue, unless it’s for a recall

but, it is:

JVM 1540 DN 1

could it be some capacitor in the control panel?

it’s probably not gummy in the fan, since the unit is new and never used

hope to hear some intelligent responses to this before I use plastic explosives to take it out of the “built-in” position

B3

4

There is the motor run capacitor which is located behind the control panel. The capacitor is used for more torque and electrical phasing.

So the problem can be a bad capacitor (strange for a new microwave), something wrong done during the installation or something interferes with the blower wheel.

Gene.

5

Gene, now I only wonder if I can get to it, being “built-in” and yes, it is strange if that’s it. There’s no blockage of the wheel spinning because I can move it by hand easily and then, as I said, it starts up easily (and there’s no damper in the way) I couldn’t imagine any back pressure enough to stop it starting, so the capacitor should be the fix. Is there a way to test it before I order the part? I know how to run a multi-meter

6

Disconnect one of the leads from the capacitor. Discharge the capacitor by touching the metal end of a screwdriver to both terminals at the same time.

Touch the capacitor terminals with your ohmmeter test leads. Reverse the way that you were touching the capacitor terminals with your ohmmeter leads.

If your meter is an analog then the needle should swing to 0 Ohms and then swing back to infinity. If it does that then the capacitor is good.

If your meter is a digital then it should display some numbers for a second and return to OL. That means the capacitor is good.

Any other readings means the capacitor is bad.

Gene.

7

Gene, it is so nice to have genius to call on; this is worth at least one glass of wine if you ever come North (more glasses if I can un-build-in the unit, dis-assemble the control panel “easily”, fewer if I have to use plastic explosives to get it out, or once out the capacitor is not the problem)

8

You do not have to remove the whole microwave to open the control panel. Just remove the top grille and you will see the screw holding the control panel.

Gene.