Stephen S Waipahu , HI June 26, 2015 Appliance: Maytag Refrigerator MTB2456AEW Maytag Refrigerator Mtb2456aew: Malfunctioning defrost cycle. How to replace Defrost Thermostat (Bi-Metal). Replaced Defrost Timer and Defrost Thermostat 3 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: 30-60 minutes