Found that Evaporator fan had failed, without the fan to circulate any air around the coil, the defrost stat was kicking in the defrost heater. Without circulation from the broken fan, the bottom of the evap coils became warm, while the upper portion remained frozen over allowing the defrost heater stat to remain closed. The defrost heater element finally failed from remaining on for an extended period of time. Ordered a replacement evap fan, defrost stat, thermistor, and defrost element. Parts came super fast. Problem solved in less than an hour from opening package. I have always had excellent service with APP.