Robert V Rockledge , FL November 02, 2014 Appliance: Maytag Refrigerator MTF2155DRW Maytag Refrigerator Mtf2155drw: Defrost heater. How to replace Defrost Thermostat (Bimetal). Replaced defrost heater, timer and thermostat this repair would have been a great deal easier and much less time consuming if I had started with appliancepartspros. Do-It-Yourself Rating: Repair Time Estimate: 2+ hours