The frost free feature of the freezer was freezing over with ice and cooling coils were being insulated with thickening frost which caused the cooling air to rise in temperature from -5 degrees to 20 degrees.

I troubleshot the problem by reading the electrical schematic and concluding the heating elements (defrost cables) were either defective or the bi-metal temp sensor was open. When closed the temp sensor completes the circuit for the current to flow through the heaters to defrost the cooling coils every 8 hours and then when the bimetal opens at 55 degrees the circuit is open and the coils are cooled because the refridgeration motor is in run mode. A timer between the motor and heater elements also was defective. The timer controls the cooling period and the defrost period. I ohmed out each part according to the spec sheet of normal resistance of parts and thus the bimetal and timer were defective. I gather a surge of some duration and amplitude affected these parts because a storm 24 hours prior to refridgerator problem had passsed through the area and the AC electrical power had oscillated several times during that event. I used hand tools to do the repair. If you are not mechanically inclined a step by step proceedure would be moot. It is a matter of disassembly and assembly paying close attention to fragile parts.