Freezer won't defrost, coils full of ice.

Dave, you are throwing me a little here. By jumping line to defrost you should have 120 V. at the heater. J-11 to j-9. Are you measuring voltage? Lets ohm out the circuit. Unplug the refer and disconnect the blue connnector from the main board. Measure between the blue wire on the connector and the orange wire on J-7 pin 9. This is right to the right. You should have approx 22 ohms. If you don't have this the problem lies either in the heater, harness,or defrost T-stat. The Tstat sits on the evaporator, opens at 140 degtrees and closes at 110 degrees. So it should read closed. Let me know how you are doing, Catriver