Tom A Ridgecrest , CA June 10, 2016 Appliance: Maytag Refrigerator MZD2665HEW Maytag Refrigerator Mzd2665hew: Fridge not cooling freezer eval coil frosted over. How to replace Appliance Light Bulb. Ended up being the defrost sensor. Ordered the heater and control board just in case. Started with the control board still didn't defrost. replaced the sensor and all is well. Super helpful tech staff answered all my questions... 44 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: 15-30 minutes