How to Troubleshoot & Replace Whirlpool AP4429884 / W10269458 Microwave Door Interlock Switch

I have a Kitchenaid KMHC319ESS-0. On this model, the keypad is on the door, and the entire microwave front surface is one big door. I didn’t find any helpful illustrations or movies on the internet for this model, but I can share that it is unnecessary to uninstall the unit for door switch replacement. If you open the door, there are 3 screws holding the plastic indoor vent; remove those and the plastic, then the fourth, single screw holding the vertical plastic piece on the right of the microwave, then slide this piece up to disengage the tabs. From this point on, switch replacement is like what you see in the videos. If you are careful, you can save $ by buying three of the w10727360 switches instead of those two $20 switches. The left position of the top assembly has connections to all three switch terminals (common, NO, NC) but the right top switch and lower switch only have two of their terminals used. Carefully note in each case whether the connections are to the NO or NC terminal (they are marked on the switch body), then wrap a piece of electrical tape around the unused terminal and install. One piece of advice is to disconnect the wires so that the switch assembly is completely free of the microwave before trying to remove the switches from the assembly - it will make it much easier to not break the mounting tabs. When reassembling the plastic vent, either a pair of needle nose pliers or a magnetized screwdriver is needed to get that rightmost screw in place. This is only speculation on my part, but it appears that opening the door (for example) doesn’t hold one switch state until the door is subsequently closed, but instead cycles the switch, and the switch output looks like a logic state change to the computer. If you inspect the mechanism, you can see a bump on the switch actuator so that in the process of closing the door, the little button on the actual switch is depressed then released, not held in the alternate position. I bring this up because a switch that is sluggish might appear functional if checked with an ohmmeter, but it has to respond quickly when the plastic bump goes by, or the computer won’t get the correct information from the switch. 

It is difficult (if not impossible) to remove the electronic switches from the hard plastic latches. I replaced all three switches and both the upper and lower latches I also replaced the main 20 amp ceramic fuse which blew out when the latch/switches failed. 

I'm a 56 year old divorced woman. I started doing these kinds of repairs to save some money and honestly, to see if I could. So yes, if I can do it, it's not that tough to do. My microwave is built in above the stove - getting it down and back up was the hardest part of the job. An extra pair of strong hands really helps-for anybody, not just a 56 year old woman. The actual repair was pretty easy. Most likely problem was pretty obvious after a little research. Easy to take off cover, get to parts, swap for new ones and put it all back together. TIPS: MAKE SURE YOU HAVE THE OLD PARTS IN HAND SO YOU KNOW EXACTLY WHAT TO ORDER AND TAKE PICTURES WITH YOUR PHONE EACH STEP OF THE WAY. If you're a newbie like me, it's the only way you'll get everything back together correctly. Also, microwaves can kill you - take all the necessary precautions you'll see in videos. 

I replaced the three switches and two supports inside the control panel. 

Ordered two switches , looked at diagram took out old and replaced with the ones I purchased from appliance parts pro.com. very easy to do. 

I REPLACED ALL THREE SWITCHES 

Replaced the 3 micro switches and the switch interlocks. I would recommend when changing these out to purchase the new interlock holders. The microswitches snap in place but when try to remove the side clips snap. For the extra 20.00 for both interlock holders well worth it. I had to order after the fact but received the next day. Within 30 minutes I was done and microwave works perfectly. Thanks for the great prompt service. 

Replaces all 3 micro switches. Not first time I had to do this. 

After locating an electrical circuit diagram, determined the 1st area to look at where a direct short could occur would be the door interlock switches. Testing and then disassembling the switches showed two of the three micro switches were welded closed, definitely, a higher rated switch could be used in this circuit. Replaced the micro switches AND the interlocking support where the 2 switches mount ( I ordered the interlocking support because I assumed the plastic retainers would break when changing the switches - and they did!). 

Ordered all new door switches and a ceramic fuse. Replacing fuse brought it back to life. Upon initial testing, operation was good and repeatable, so I forwent the switch replacement and later used the machine to cook (3) sweet potatoes (at once) using the "Potato" auto sensing button. It then threw an "F4E4 Humidity Sensor" error code. I'm assuming other auto features are either bugged or broken, as well, but standard operation via number pad is dependable so far. Cooked the potatoes for 9 minutes with no issues. I'm also assuming my problem likely lies in the circuit board, not the switches, and whether or not that was the initial culprit or if I caused it when blowing the fuse is anybody's guess. If replacing the board is cost and skill friendly, I'll likely swap out the switches at time of that repair.