Freezer coils ice up, not letting air pass thru coils, for proper refrigerator & freezer temperatures. I found a black burned out defrost heater at the bottom of the coils, last week. I replaced it, this did not help, the coils froze up again and I haven't seen the new defrost heater work. I saw on the repair forum, that someone had a problem where they measured an open on the defrost heater and defrost thermostat. So I thought my defrost thermostat went bad, also. I ordered a defrost thermostat from Appliancepartspro.com and recieved it 8 June 2010. I installed the defrost thermostat this morning and the freezer coils are iceing up and the heater has not worked. I still have a bad refrigerator/freezer.