ACM1420AB - Instructions

Unplug microwave! It's NOT necessary to remove microwave from above stove. Removed two Philips head screws on top front of unit to remove front grille. Removed one screw to remove control panel, letting it hang down. Found inline fuse in cabinet where line cord wires come in. Pulled out blown fuse with thumb and forefinger. Snapped in new fuse, replaced control panel and grille with the three screws. Plugged in the microwave. -Worked great! Good opportunity while grille was off to clean it and replace the charcoal filter inside the cabinet.

Initially we started looking to buy a replacement microwave to replace our 13+ year old built-in microwave. It was a real pain finding a replacement to fit the exact dimensions. So I thought I'd try to find an old KitchenAid microwave. However, I was pleasantly surprised when this site came up on my search. Their website allows me to input the problems and then it showed two possible parts that needed to be replaced. I emailed tech support and asked them which part I needed. They responded very quickly and said I needed to replace the magnetron. I watched a couple YouTube videos and then pulled my microwave apart. It was incredibly easy to pull the outer cover off. The magnetron had 5 screws that needed to be removed and one electrical plug. Took me maybe 10 min to complete the entire repair. It was one of the easiest repairs I've done and so thankful for this site They saved me a ton of money from not buying a new microwave and we now have our microwave working again. In hindsight, I wouldn't hesitate. I'd order the Part now and get it fixed.

well I unplugged the microwave one day prior to working on it. shock precaution smart way to do this job. very easy pullout the screws behind the unit pull off the outer casing. minor screws inside the unit you have to remove a couple things out of the way. unplug the magnetron and remove first gives you more room to work on the side panel to replace the micro switches. I only replaced one the bottom micro switch. only one bad, but since I was in there I clean the bulb and changed the magnetron any ways. I read other reviews and made my choice to do so. it works perfectly now. Thanks PartSelect for having parts.

Unplug the microwave. Remove the Philips head and safety Torx head screws along the bottom of the sides and rear of the microwave which hold the black cover on. Lift the cover up at the rear and slide it backwards to disengage the tabs on the front top. Remove the cover. Discharge the capacitor by shorting the terminals to each other and then ground. Do this with a well insulated object and be aware there may be a pop when you do this. Keep hands, etc. on the insulated part of the object (screwdriver handle, etc). There's a lot of stored energy in that capacitor. I'd advise first checking the diode to make sure its not bad. Replace it if it is. The Magnatron is held in with a couple of screws on the top and sides. Unplug the connector and remove the screws. Remove the Magnatron. Installation is the reverse of removal.

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.

The power on the microwave went completely out when I went to use it, but there was no power failure for the house or neighborhood. We removed the microwave from above the oven. Took out the screws on the sides and back of the microwave and slid the top back. The line fuse was located on top unobstructed, NOT behind the button panel like some microwave models. As the appliance is over 20 years old the line fuse was quite old. It was really hard to pry it out of its holder and actually broke. I used a vacuum to suck up the dust and glass and it was easier to get out the ends once the middle broke. Popped the new line fuse in, slid the top back on, put in the screws and put the microwave back in its compartment above the stove. Good as new!! We were about to spend money on a new microwave, but thankfully I came across this site. So happy I did!!

This repair was really easy. The part that took the most time was taking it down from it's compartment above the oven and putting it back up there once repaired.

Removed some cosmetic panels. Removed the assembly with micro switches. Examined the faulty switch by checking the clicking action of switch. Two others were ok by this method. Replaced the switch with new one. Works fine so far. Thanks to web site and YouTube videos.

removed a dozen screws-discarded large cap-replaced diode-replaced a dozen screws(took longer to replace them than remove for some unknown reason). Microwave now works(wife happy).

Took microwave out of builtin cabinet with 4 screws.
Put microwave on center island and removed cover.
Tested interlock switch with volt meter and it appeared ok so I put my kit back in box and sent back.
Took out magnetron unit and replace with new part.
Put cover back on and test.
All is working and installed back in cabinet. Two weeks later all still working great.

The instructions on the website were incredibly easy and I saved myself a lot of headache by using this site.

-it was built in unit - so I needed to pull the decorative grill from around the outside to remove it from the wall
- removing the back of the case involved removing phillips head screws from along the side and back of the unit. the only issue I encountered on removing screws was the fact that the "torx / star" screws could not be fit with the wrench that I had (they had a pin in the center that would not allow the wrench to fit into the star). However, a pair of pliers was handy and they were removed just easily.
- I had ordered both the high voltage diode and magnetron because I didn't know which item was the problem. I grounded the diode with two screwdrivers while wearing rubber gloves to be safe. the warnings on this did the trick as it was the only scary part of the operation.
- the diode was a little hard to spot looking at the schematics, but is is found on the lower right corner of the right side of the panel and easily pulled out and replaced. I tried the microwave again to see if it worked...and it did not. So I confirmed that the magnetron was the issue.
- removing the screws for the magnetron and putting in the replacement was a dead easy and I tried the microwave again before putting cover back on. Worked like a charm. Super easy!

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).

Part select made it very easy for me to purchase a replacement plate, which I didn’t think I was going to be able to find so thank you part select for having what I needed

Take cover off microwave. Check door switches to determine which one was faulty.Remove and replace faulty switch.

Using fingers, the old turntable roller guide was pulled up off the motor shaft. The plastic roller guide shaft coupler was found to be broken, allowing the motor shaft to spin without turning the roller guide. The hole in the floor of the oven was inspected, and no broken pieces were found which could interfere with the new roller guide. The new roller guide was then gently pressed down over the motor shaft. Very easy.

It seems that the heat of the microwave cracks the part over time. It is a very simple installation.