The Norcold defrost cycle is VERY SIMPLE. When the refer is left ON, every 48 to 54 hours, the refer will shut off for a few hours. NO HEATER is involved. This just allows ice accumulation on the evap fins to thaw and drain off. You will never know this happens. To STOP this cycle is simple. You just turn the refer OFF for 5 seconds and then turn it back ON. Every day. Each time you do this, the 48 to 54 hour timer resets. The reason for this auto defrost is, ICE on the evap fins is a insulator and with ICE, the refer cannot remove the heat efficiently. This has NOTHING to do with the freezer. The freezer you still have to manually defrost. Doug