Report "The refrigerator cools great, however we have a problem with it freezing up about every 2-3 days. The evaporator coils become completely incased in a sold block of ice. The manuel says it will automatically defrost for a few minutes every hour. According to the display it is doing that. The compressor cuts off and the display reads "def". A heater is supposed to come on to melt the buildup of ice. I opened up the evaporator area, and the heater doesn't appear to be coming on. My guess is either the heater is burned out, or the microprocessor is not activating the heater or both. There may be a problem with the microprocessor, because the manuel indicates the circulation fan should turn off to prevent circulating hot air through the refrigerator during the defrost cycle, and it doesn't appear to be doing that"