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So it sounds like your unit is not defrosting on it's own. Too much frost blocks the air from getting up to the refrigerator section from the freezer. You'll need to remove everything out of the freezer and remove the entire back panel inside the freezer and use a multimeter to test continuity through the defrost heater and the defrost thermostat. The thermostat is a 1" round device with 2 wires going to it clipped onto the top of the silver evaporator coils. If you don't have continuity through the heater or the thermostat, you'll need to replace the part. Now if the fan above the silver evaporator coils isn't running, just replace the fan motor because that is the fan that blows air up into the refrigerator so that the refrigerator can cool down.
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