[jsarp59]

Our microwave will cycle and when we open the door after cycling it blows our house circuit in the circuit box. Yesterday after I blew the circuit I could not reset the circuit in the circuit box. This morning the circuit reset but as soon as I pushed the button to open the oven the circuit immediately blew again. Any ideas?

[Gene]

Hello,

Remove the outer case and check the door interlock and the monitor switches.

Here are the breakdown diagrams and Parts for Maytag MMC5000BDW Microwave - AppliancePartsPros.com

Gene.

[jsarp59]

Opened the microwave. Nothing looks fried. The fuse in the microwave looks fine. Assumed it would be since the house circuit is the one popping. Located the four door switches. Suspect one of these may be the problem?? But seriously, what do I know. Is there a way to test these to see if they are working properly? Didn't see any loose wires on the switches.

Anything else I should look at?

[Gene]

Originally Posted by jsarp59

...The fuse in the microwave looks fine. Assumed it would be since the house circuit is the one popping...

...Located the four door switches. Suspect one of these may be the problem?? But seriously, what do I know. Is there a way to test these to see if they are working properly? Didn't see any loose wires on the switches...

The microwave build-in fuse should blow first. Possible the house circuit breaker is bad.

Visual test does not work with electrical parts. You have to test the switches for continuity with the door opened and closed. The wires have to be removed from the switch terminals prior to testing. Draw a picture for yourself of the wire connections so you would know how to reconnect them properly.

The following article on our forum will explain in detail how to run a continuity test - How To Check Continuity With Ohmmeter

Gene.

[jsarp59]

I also felt that the fuse should blow first but wasn't sure since both the fuse and the circuit breaker are 20 watts. Out of curiosity I plugged my microwave into another outlet and tried it. We opened and closed it 5 or 6 times and it worked fine. Also heated some water twice for 1 minute. Fine. Then after about 5 minutes when I went to open the oven this other circuit breaker popped. So I feel pretty it is not a faulty circuit breaker. Can't explain why sometimes it works and sometimes it pops?????

[Gene]

You still have to check the microwave switches and, may be to call an electrician to check the circuit breakers.

Gene.

[sdimple387]

Circuit popping is combined with limited resistor or capacitors.

[jsarp59]

See next response

[jsarp59]

I took out and tested each switch (with a meter) individually. The three bottom switches tested fine. Cleaned the terminals and replaced. I noticed on the top switch (2 terminal switch) that the blue heat tape over the connector was black like it overheated. I tested this switch multiple times and it worked as it should. I cut off the tape and the plug didn't look melted. Just a little corroded. Not sure what I should conclude from this.

I also tested the fuse in the microwave with the meter. It tested fine also

[jsarp59]

Cleaned the top switch connectors and the plugs. Replaced the blue heat shrink tape. Microwave worked good for two days. This morning the main circuit popped again when opening the door after microwaving something. Should I replace the top switch?

Noticed the mount where the top switch pushes into only has one plastic prong that fits into the hole in the switch. Is this normal or did one break off? All the other mounts have two prongs that fit into the two holes in the switch.