ACM1420AB - Instructions

Removed micro bottom - 5 screws. One screw on the motor and a clip. Reversed the sequence, turned it on and watched it turn.

I went to LG website enter model number and was given a list of parts that need to be replaced with a percentage of which part fails the most. I order micro switch PS3522738 which arrived and PS3529293 was backordered. I installed the one that arrived. The microwave worked briefly. I reordered and waited for both switches to arrive and installed both. The microwave still doesn't work.

Put in the new part, took less than a minute...

Replaced turntable support with new unit.

i unplugged the unit,unscrewed the outer shell so that all the wiring and internal components were visible.starting at the first of three micro switches i removed the slip on terminals installed the alligator clips too the wires so the switch would now be bypassed.i made sure the wires and clips were not touching anything plugged unit in and it worked.i then installed the new switch and closed up the outer shell

Easy, and the microwave still doesn't work.

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.

Take off cover then the bottom. Transformer is on the bottom plate and wires won't let it come all the way off, too many wires to pull off so will have to position the bottom plate so you can get to the motor. Remove 1 screw on motor and remove motor. Install new motor connect wires replace bottom plate, replace cover. All done (hope & pray it works ok) mine worked perfect. Hope this helps.

Unplug.Take off the external cowling from the back of the unit by removing the torx security screws. Tip: instead use a thin screwdriver blade to unscrew the torx screws, or knock out the center pins of these screws. Remove the bottom panel. The replacement motor is attached with one phillips screw, re-attach wires to motor - polarity doesn't matter. Re-assemble and you're finished.

Initial failure of over range microwave Aug 3rd. Control Panel worked but no heat. Took to local LG authoriaed local repair place. They fixed it quickly and we re-installed it. Worked fine for 2 months then had similar failure again. Agaim took to same authorized repairer. They kept unit for 3 months but finally concluded theu could not fix it and suggested we contact LG for a partial refund. When they tested the unit during re-assembly in my presence, there was a blue flash and the fuse blew. Since we had built a custom tile mural back splash around this unit, I brought it home, ordered a number of time delay fuses new capacitor and two new high voltage diodes. However, using my Fluke DMM, I checked the existing capacitor and high voltage diode and they checked OK so I just replaced the time delay fuse. The high voltage transformer leads had 2 possible ways to connect to capacitor and diode. Tried one way, plugged unit in and turned it on, and immediatly blew the fuse. Replaced the fuse and reversed the high voltage transformer connections,amd turned unit pn, and it worked perfectly. Since we had experienced several power failures during the time of the original failure, the repairer concluded that power spikes might be at fault, so I also purchased a TrippLite ISOBAR4ULTRA 3300 Joule surge protector between wall outlet and microwave, and re-installed over range. It has worked perfectly since.

Ordered the switches from Partselect, arrive in two days. Had trouble removing the plastic connectors from the old switch terminals, one of the plastic protectors broke, but was able to reuse it. It took a little figuring out how to remove the existing switches. Must push in a tab and rotate the switch on a little pin, then remove. Must be careful not to break the plastic tabs holding the switches in place. Replaced all (3) switches at the same time. All in all it was pretty easy.

The turntable wouldn't rotate any more. The problem was the plastic roller guide (under the turntable glass) had cracked where it attached to the shaft. I installed the new part, it fit perfectly, now works great!

Partselect sent me the right thing in two days! The whole process was easy as pie.

Opened the package and inserted the turntable roller guide. It was the right one and worked immediately!

The door was not engaging the micro switches properly no doubt from 10+ years of wear. The upper switch removed fairly easily but take care not to tweak the plastic brace too much or it will snap. The lower one was the tricky one. After much examination I noticed that the trick to remove it was underneath the brace. Take a butter knife (no joke) and insert it just under the old micro switch and gently press down twisting the micro switch every so slightly til it releases. The replacements snap back in with no trouble. The microwave is working much better now, though not perfect.