Biscuit should have explained the Defrost cycle. All it is, the refer just shuts OFF for about 2 hours every 48 to 54 hours, IF LEFT ON CONTINUOUSLY, and that allows the fins to warm up enough to get rid of the ice accumulation. Ice is NOT a good conductor of cold and actually insulates to prevent optimum cooling performance. If you do not want the defrost cycle to happen, just turn the refer off and on once a day and the defrost will never happen. That resets to 48/54 hour timer. There are NO defrost heaters on these models that have the built in timer. Doug