I went on this service call, this is called a bottom mount refrigerator(Refrigerator on Top, Freezer on Bottom), and the freezer section was freezing and doing good, but the refrigerator section was warm above 50 degrees.

I opened the freezer door and heard the evaporator fan motor running and saw lots frost build up at the bottom vent on the back panel inside the freezer, I removed the freezer door, shelves, and ice maker, then I removed the back panel inside the freezer, and the evaporator coil was completely frosted up to where I couldn’t even see the coil.

Before I defrosted it I unplugged the refrigerator, and ohm tested the defrost thermostat and it read closed(continuity) on my multimeter, so I knew that was good, then ohm tested the defrost heater and had 11 ohms and that was good. So the only part left that would cause this is a faulty control board(JAZZ).

Remember: Before you replace the JAZZ board you MUST defrost the evaporator coil first! I used my heat gun to defrost it.

Here’s the JAZZ board for this model:
WPW10503278 Electronic Control Board