Hi, my name is Peter.
With no air flow to the refrigerator side check the fan motor is the freezer and see if it is running. If the fan is running the check if there is ice build up on the back wall of the freezer. If there is ice build up then the automatic defrost is not operating and obstructing the air flow to the refrigerator and to the upper part of the freezer. You will need to remove the lower back panel of the freezer and check the heater and thermostat (a small round disc clipped to the top of the evaporator) and see if both have continuity. If they have continuity then you have a defective defrost control which is located in the right rear corner behind the temperature controls in the refrigerator.
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