Roper rt18bkxkq00 fridge warm, freezer cold. What parts do i need to repair?

Refrigerator & Freezer Repair
1

Please make sure to click on General above and select the correct appliance type first.

Brand: roper
Model Number: rt18bkxkq00
Main Symptom: fridge portion too warm.
What happens & when: Motor turns on and off intermently. Fridge is warm, freezer is cold with frost build up

Error Code (if any):
Parts or tests already tried: I think I need WPW10511937 but want to confirm before purchase
Photos / video link:

2

I would put the 2 wires together on the thermostat or when it shuts off tap the thermostat and see if it comes bad on before buying it.
Roper Whirlpool RT18BKXKQ00 Refrigerator Wiring Sheet-2217549-Rev JY.pdf (3.0 MB)