AMV4204AAW - Instructions

I had to unmount the over-the-range microwave oven to be able to gain access to the interior of the oven. Complicating removal (and re-installation) was the fact that there is a "pot-filler" faucet installed directly underneath the oven. In retrospect, I should've removed the faucet before doing the repair, but "c'est la vie."

After I got the microwave down, removing the case was also "interesting." I get bonus points for the fact that the previous owner must've had to replace the same diode before - and then re-assembled the microwave case incorrectly - thereby adding to the confusion (BTW, the service manual that I found online said nothing about how to remove the oven's case).

To remove the case, undo all the screws holding it on, and then rotate the case upwards from the back while also pulling the case backwards. There are crimped folds on the inside of the case that mate with the back edges of the front of the oven's chassis, and these folds have to be unclipped from the chassis in order to remove the case.

Replacing the diode itself was the easiest part of the job. The two connectors on the diode are of different types, making it impossible to install the diode with the wrong polarity.

BTW, the diode that had failed was not an OEM diode; I suspect it was a generic component that had been installed by a repairman sometime between 2004-2008 (when our home's original owners still owned the home). On the other hand, the new diode from PartSelect is an OEM part (it came packaged in a sealed Whirlpool bag).

The fact that the oven had stopped heating indicated that it was either the high-voltage diode or the magnetron that had failed. Since a replacement diode costs ~ 1/10th as much as a replacement magnetron, I figured it made sense to replace the cheaper part first. Fortunately, this fixed the problem.

One last thing: I tried testing both the old and new diodes for conductivity and polarity using my volt-ohm meter (VOM), but I was unable to get either diode to "turn on," even though my VOM is powered by a 9-v battery, and I used the 2-Mohm range setting. I guess the test voltage of my el-cheapo VOM isn't high enough to exceed the diode's threshold voltage, (even though I have successfully used this same VOM to test low-voltage diodes).

Unplugged the microwave. I opened the door. I used a butter knife to pop the bezel off the inside of the door. I pushed the locker up and to the left and used the butter knife to pry it loose. Disconnected the locker from the spring, and reversed for the installation.

Repair was very simple, removed microwave from wall and removed top cover and found fan loose on shaft. Removed fan and motor, new motor and fan slotted, good upgrade. Installed new motor and fan and top cover on, installed back on wall plate, tried and wife said it sounds like a new one.

Watched a you tube video prior to installing new switch. Followed the video which gave me confidence i was up to the task. After removing the touch pad I found my design was not exactly like the you tube model but I found the defective switch, replaced it and put the microwave back together. Works great. Again watch the videos

You Tube

Replace (after testing w/ohm meter) diode and locker holder. My door often would not close properly. Microwave let know by saying not shut properly. When disassembled found the top screw mount was hollowed out resulting in it moving on occasion when you close door. First remove casing (special safety torx head) needed for rear screws. Onc e removed all parts available to view or work on. Diode is on the capacitor so caution is needed when removing. Serious shock hazard if touched. Use insulated pliers to remove from capacitor and a phillips on the ground. Test with ohm meter Should have resistance on way and non the opposite. Replaced mine bad. Next the holder 2 phillips screws and its yours. Unplug each switch and remove. Take note to what wires go to what switch and what switch mounts where. Mine had 3 switches. Removed from old holder and put in new. Screwed holder back in place and left scrws loose till re wired. Once wired set the holder by lightly tighting the screws. Try the door till it seats properly ensuring that all 3 switches are working properly. If so thighten screws. If all seems to work as advertised, safely plug in and test unit if heats up un plug and put cover back on micro. Your all set. Happy heating.

I had a son put in the new light bulbs. Rather simple

I looked up my problem on the internet and found a very helpful video. Microwave on video was different brand but the internals and methods were very much the same. The video made it simple and easy to fix. Found the replacement switch on the LG parts site and ordered. Two different switch types. One with red switch, the other green. Part was $7.28. Saved a bundle in service costs. Here is the repair video.

https://www.youtube.com/watch?reload=9&v=_AglBJoHgDs

just lift the glass turntable off and take the ring out and put the new in and put the glass back.

tested cap. with ohm meter which showed a short. A new HV cap., a fuse and it is working fine again.

It was not the magnitude of the repair but the fact I ordered the part on a thursday and it was delivered on saturday. Timing ws very important, especially this time of year.

using the measurements shown in parts catalog, it appeared the item I needed was correct for what I ordered.

Philips screwdriver
Removed screw (1)
Removed light bulb
Put in new light bulb
Closed door to bulb compartment
Returned screw.

Pro tip! Check how many bulbs you need before ordering. Mine only needed two. I got two. I suspect I’ll buy a new microwave before new bulb burns out again. Ordering/delivery was fast. No need to have spare on hand.

I UNPLUGGED the microwave and removed the cover, using a phillips and a Torx screwdriver for the machine screws. I set these screws aside, so as not to confuse them with the later encountered screws. I photographed the magnetron to assure proper placement of the 6 phillips machine screws involved in reassembly (marking the the locations on the old magnetron would do as well. I marked the old magnetron "old", to avoid later confusion. I removed the two screws holding the shields to the magnetron. I removed 3 of the 4 screws holding the magnetron to the microwave, leaving one of the top screws. I held the magnetron securely and removed the last screw, pulling out a the part of the magnetron that penetrated the microwave. I installed the new magnetron in reverse order. One problem I encountered was locating one of the six screws, which had been pulled into the old magnetron by magnetism.

remove the part from the box and wipe it down with warm soapy water, rinse and dry and place in microwave.