Christina S Beaumont , CA July 22, 2019 Appliance: Whirlpool Refrigerator GX5FHDXTS01 Whirlpool Refrigerator Gx5fhdxts01: Freezer icing over and not cooling the refrigerator. How to replace Defrost Heater. I had to remove everything from the freezer in order to access the defrost heater. Once accessible, I swapped out the old one for the new one. Hopefully, it solved my problem. 6 months ago, I had to replace the defrost thermostat. Do-It-Yourself Rating: Repair Time Estimate: 30-60 minutes