The fridge compartment quit getting cold enough. Took the back panel off freezer section - heavy frost buildup. Following your guidelines, I turned the Def Timer manually until it went into def mode. No heat to heaters. So, I jumped around the Def Thermostat and the heaters came on. (I don't remember now if I did that while it was cold or warm.) I ordered a new def thermostat from you and replaced it. No change - the fridge would only go down to around 60. I then ordered a new def timer from you and replaced it. Not much improvement. The fridge will only go down to about 49. The freezer makes ice (but cubes clump together) and the coils are still heavily frosted - especially those above the top heater. When I watch the heaters working the bottom one is much brighter and hotter. I haven't replaced the back panel that hides the coils yet - would that matter? Is there a possibility one heater isn't getting warm enough or is getting too hot? What should I do next?

The heaters are working. I can see them light up and feel the warmth. They do defrost the coils. But the frost re-accumulates after a while. Is there any other module or circuit board to check? Is there a way (easily) to check if the heaters are working properly? I've already replaced two componenet without success.

Yes, I just put a new Def Timer on and the Def program works as it should. The coils defrost during the def cycle. But it seems that the top set of coils (the ones above the heater that doesn't get as hot or bright) get more heavily frosted and quicker. Is there a way to determine if the heater (even though its working) isn't working right?