SubZero Refrigerator Freezer Error Code 21 – How to fix? by KatyApplianceRepair.com
Sub-Zero error code EC 21 indicates
a defrost overheat condition. Below is a quick reference
and troubleshooting guide for this code.
Quick Reference
| Error Code | Meaning | Severity |
|---|---|---|
| EC 21 | Defrost overheat — evaporator temperature exceeding safe limits during defrost | Medium |
Cause & Solution
| Cause | What to Check | Fix |
|---|---|---|
| Defrost terminator (bi-metal) not opening | Test the defrost terminator for continuity | Replace the defrost terminator if it stays closed |
| Evaporator mounting issue or faulty wiring | Inspect evaporator mounting and wiring connections | Repair wiring or re-seat the evaporator assembly |
Need help with EC 21?
Call (281) 688-6685 —
Katy Appliance Repair: same-day Sub-Zero diagnostics in Katy, TX.