How to Troubleshoot & Replace Samsung AP4455982 / DE31-10172C Microwave Ac Drive Motor

I replaced the motor and the turntable coupler 

Found the food we were cooking was burned on one side. Turned on microwave for a 30 second run and noticed the turntable was not turning. Said to self, "Rats have to buy new microwave and started pricing them...ouch." Said to self, " Pull microwave from wall cavity and check it out." Found the bottom removed with only 6 screws and the turntable motor was removable with a single screw and a plug. Tested the current to the motor to be sure the issue was with the motor itself. It was, the current was as it should be. Looked up the microwave model number, went to AppliancePartsPros.com, and looked up the motor part. Found it to be one heck of a lot less expensive than a new microwave. Since the coupler came apart in my hand when I removed the motor I also ordered that part. Total cost: $37.95 vs about $600 for a new microwave. Got the parts the next day. From getting the parts from the mailbox in front of the house, finishing part installation, testing the turntable function, and reinstalling the microwave in the wall cavity: 45 minutes. Only tools required: my small electric screwdriver with a #2 Philips bit and a cheap multimeter. Happy Tinker. 

Installed new motor. 

Removed faceplate 

I ordered a new coupler and a new drive motor. It appears the coupler was cracked. I also replaced the drive motor to be safe. Parts came in day and a half. Very smooth transaction and no problems at all. Great job. 

Replace motor. 

Removed 5 screws from bottom panel pulled wires off motor and replaced it. 

I made sure the connector wasn't broken. Once I confirmed this, I replaced the drive motor part as suggested. Easy to replace and it now works! Only reason I don't give it a 5 star is because the part was expensive; about a third of what the microwave cost. However, replacing the part myself was cheaper than buying and installing a new microwave!