Bruce T Birgie , KY January 19, 2020 Appliance: Whirlpool Refrigerator WRT318FZDW02 Whirlpool Refrigerator Wrt318fzdw02: Icing in the freezer section and not cooling in refrigerator section. How to replace Thermistor. Replaced the defrost sensor and used compressed air to clear the drain line. 4 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: 30-60 minutes