I went out to this refrigerator and found the back panel inside the freezer had massive frost build-up on it. I first unplugged the refrigerator from the wall electrical outlet, then ohm tested the defrost heater and found it was bad, meaning the numbers on my digital multimeter didn’t change. Normal ohms for most at defrost heaters is mainly about 30 ohms or less.
I completely defrosted the entire evaporator coil, which is located behind the back panel in the freezer, then I removed the old defrost heater assembly and installed the new defrost heater assembly, worked great!
Here’s the defrost heater assembly for this model:
WR51X10055 Defrost Heater and Bracket Assembly