I have the same problem with the MZD2766GEW. I read continuity on the defrost heater element and have 240K ohms on the defrost terminator thermostat indicating it is open. But I don't know if it will close. Is there a way to by-pass the defrost timer circuit to bring the defrost heater in? This would test the thermostat, element and wiring. If all are good, the only other problem would have to be the PC Board (defrost timer). I would like to test further before I buy a new defrost timer. Besides, it not easy to remove the timer because of the temp control for the refrigerator side. | 
