Lfxs26973s fridge not cooling

Refrigerator & Freezer Repair
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1

Brand:LG
Model Number:LFXS26973s
Main Symptom: fridge not cooling. compressor is warm, freezer still ice cold.
What happens & when:

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

2

You will want to check to make sure that the evaporator coils is not frozen over. If it is then check the defrost heater, thermistor and if they are good then the control board would be faulty. if the coils are not impacted with ice then check the air damper in the refrigerator to make sure that it is good. While your in the freezer check to make sure that the air duct behind the evaporator is not frozen over with ice. This will normally be accompanied by ice freezing the drain trough over.

3

evaporator coils are not frozen. the air damper is good as well. how do i check the defrost heater or the thermistor?