Diagnosis
The damper door between the freezer and refrigerator sections is stuck closed. The refrigerator cannot receive cold air.
How to Fix It
Locate and manually exercise the damper. Remove the upper refrigerator shelf and the plastic cover at the top rear of the fridge compartment. You will see the damper door. Gently move it back and forth to ensure it pivots freely. Remove any visible ice or debris.
If That Didn't Work
The damper motor actuator may have failed. Listen for a faint humming or clicking from the damper area when the refrigerator calls for cooling. No sound indicates a bad motor. This requires part replacement.
Heads Up
Do not set the freezer control colder to compensate. This will not fix the fridge temperature and can cause freezer burn. The refrigerator control should be at 37°F and the freezer at 0°F for diagnosis.