Galen L Amherst , NH August 24, 2020 Appliance: LG Refrigerator LRBN22511TT Lg Refrigerator Lrbn22511tt / : Refrigerator not cooling. How to replace Defrost Sensor Assembly. I replaced the two most-likely culprits: the start relay and the defrost sensor and my fridge is working again good as new! 2 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: 15-30 minutes