please help

hello, my freezer and fridge seem to work on the lower half. top half too warm. looks like my evap coils inside freezer section are freezing up getting frosted over, dont think the fan is turning on in freezer. what should i check, is fan bad or could it be something else? thx Jeff

I would replace both the motherboard in the back AP4436216 and the evaporator fan motor AP3875639 (Without thermistor wired in the harness) or AP3191003 with thermistor.