GE Refrigerator, freezer working fridge warming up

Refrigerator & Freezer Repair
1

Brand: GE
Model Number: GSH25JSDD
Main Symptom: Freezer cold/Fridge warm
What happens & when: Appliance is about 12-15 years old. In the last 3 months, the freezer is working normally but twice now the refrigerator stops cooling and I have defrosted completely overnight and then plugged it back in and it works again for a month or so.

Error Code (if any):
Parts or tests already tried:
Photos / video link:

2

Check the evaporator coils to see if they are frosting up. If they are then test the defrost heater and defrost thermostat and/or thermistor to make sure that they are good. If they check ok then the issue will be with the control board.