Brent Z Marysville , OH October 16, 2023 Appliance: Frigidaire Freezer FFU21F5HWK Frigidaire Freezer Ffu21f5hwk: Hi temp fault. How to replace Defrost Thermostat. Ordered the ECU for a 13 year old Frigidaire upright freezer on a Thursday morning, received the part by Friday afternoon. Removed the bad ECU and replaced with new, took about 30 seconds. Freezer is working like new. Do-It-Yourself Rating: Repair Time Estimate: Less than 15 minutes