[TWA]

This Kenmore microwave worked fine for 4 years until yesterday. Now, when you open the door, the thing turns on, the platter turns, and it is microwaving. When you close the door, and it stops. If you need to cook food, it still works normally with the door shut - even turns off on time. But open that door, and it turns on again.

Obviously, this is not safe, because I think microwaves are escaping.

My initial impression is a circuit board malfunction. It almost acts like it needs to be reset - or rebooted as with a computer. I don't know how to do that, however, and unplugging the thing for a minute and plugging it back in does not make a difference.

Mechanically, the door opens and closes normally, and the latches look OK.

Please let me know any ideas on this odd problem. Such as, what parts might be at fault, and how to fix it.

Thanks,

TWA

[Gene]

Originally Posted by TWA

... when you open the door, the thing turns on, the platter turns, and it is microwaving...

How did you know it is "microwaving" when the door is open?

Gene.

[TWA]

Gene, I checked to see if food became hot when the door is open and the fan and turntable are working. In fact, the food did not heat up, so I think you are right, and I'm now hopeful there is an easy solution here.

The microwave works properly on the timed cooking when the door is closed.

When the door is opened, the fan continues to run, and the turntable continues to turn. Interestingly, when you open the door repeatedly, the turntable changes directions almost every time. One time, however, the turntable did not move, and the fan did not turn on. So, now I wonder if there is something stuck in there that a bit of WD-40 might cure. In particular, I wonder about the lower door latch, which seems to have something to do with this problem. I don't have a diagram, and the manual is no help.

I'm very interested to read your suggestions before I take this thing apart and start spraying WD-40.

Tom

[Gene]

Hi Tom,

Most likely the problem is a bad secondary interlock switch which is usually located on the bottom part of the door frame. DO NOT use WD-40 on any electric parts - it will cause a short.

I'm not able to provide more accurate information because the model number you posted does not come up.

Gene.

[TWA]

Thank you Gentleman Gene,

I was able to find a diagram of the part #4002 at Sears Parts:

KENMORE | Model #72163252301 | MICROWAVE | LATCH BOARD PARTS | SearsPartsDirect.com from Sears

I read somewhere it is a good idea to change out both switches if one of them goes bad. They will send me the Primary and Secondary Interlock Switches for $20 delivered. If your company sells these same parts, I'd prefer to get them from you, so please let me know.

However, I still wonder if there is a mechanical part causing the problem, so I think I'll open up the microwave and take a look at the situation. I understand that it is probably not such a good idea to start spraying WD-40 on everything, especially electrical parts. My general impulse is to either use the WD, or else duct tape! I'll also try to keep the hammer in the toolbox, although that's worked in the past...

Thanks,

Tom

[Gene]

Tom,

After you installed the new switches, with the control panel removed, check how they are engaged by the door latch and adjust it if needed.

- The part number for the interlock switch is AP3153831

This switch can be used as a replacement for a monitor switch as well. You have to break off an unneeded terminal.

Gene.

[TWA]

Dear Gene - aka Appliance Sherlock Holmes,

Thanks so much for your advice. I installed the switches I ordered online, and voila! the problem is solved. When I opened the case or this Kenmore Microwave, I discovered a wiring diagram folded up in a little plastic holder, which was nice. Between that and the diagram I was able to download from sears.com parts, and your advice, the repair was very clear. Thanks again.

Tom

[Gene]

Hi Tom,

I'm glad you were able to fix it.

Gene.