I went out to the customers house and their refrigerator was not cooling in the freezer or refrigerator sections.
I pulled the refrigerator out from the wall and removed the rear lower access panel and the compressor was not running at all, but the condenser fan motor, that mounts next to the compressor, was running.
Then I checked for 120 volts AC at the two larger wires that go to the compressor invertor board and 120 volts AC was present and on the two smaller wires I was getting 5 volts DC, which means the compressor inverter was the bad part.
I then unplugged the refrigerator and I replaced the compressor inverter board and the compressor started running and it started to get cold inside the freezer and refrigerator sections.
Here’s the compressor inverter board for this model. You will see a video of how to replace it when you click the part link to the compressor inverter board: Compressor Inverter WR87X29409