William R Boonton Township , NJ August 24, 2018 Freezer was building up frost, refrigerator not cooling properly. I've had this issue in the past. I checked the door gasket and found it to be fine. So I knew it had to do with the defrost cycle. I replaced the defrost heater, timer, and thermostat to be safe. Works fine now. 1 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: 1-2 hours