i replaced defrost timer and defrost thermostat. i advanced the timer before i replaced it and the heater glowed red. it still frosts up the back wall and coils. what else could be wrong ? what am i missing ?
Mark the timer cam and a spot on the cover so you can check that the new timer is advancing.
Are you sure that it is not defrosting?
If it is just heavy frost on the walls and food in the freezer then it may be a bad door seal.