Glen D Flint , MI January 15, 2022 Appliance: Roper Refrigerator RT18DKXJW01 Roper Refrigerator Rt18dkxjw01: Freezer icing up & refrigerator not cold enough. How to replace Defrost Heater. I purchased a new thermostat and defrost heater and they arrived the next day! I checked both of the old ones with an ohmmeter and I believe they were both bad. My freezer and refrigerator are now working great! 1 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: Less than 15 minutes