Donald S Fort Smith , AR October 17, 2020 Appliance: General Electric Refrigerator GTH18CBTZRBB Ge Refrigerator Gth18cbtzrbb: Freezer was icing up and the refrigerator was getting warm. How to replace Refrigerator Defrost Thermostat. First thought was to check and change the defrost thermostat which has two. Then I read about other people having the same problem and decided to change the control module. After receiving the parts it was simple to change all of the parts. Changing the control module i found that one of the parts on the old board a capacitor had blown apart. After changing the parts the unit is running great. 2 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: 30-60 minutes