Corky H Carson , MS September 15, 2020 Appliance: Frigidaire Freezer FFU20FC4AW0 Frigidaire Freezer Ffu20fc4aw0: Evaporator freezing over. How to replace Heater - Defrost. Ordered and replaced thermostat, defrost heater element and defrost timer. parts arrived in about 3 day’s. Fast shipping easy to find and order parts. Good video Do-It-Yourself Rating: Repair Time Estimate: 30-60 minutes