temps keep fluctuating. fridge is pretty consistent 37* but the freezer is all over the place. took off panel in freezer and the top right of the coils is all iced up. actually, more above the coils. have replaced the defrost thermostat. still happening. compressor and fan running. also fan in the freezer running. being told i have a sealed unit and fridge might not be worth fixing. i can't believe it. can someone help me!!!!