Seen on: 600 Series, later control
EC 20: Defrost Under-Heat With No Feedback
EC 20 means a later 600 Series freezer went into defrost, the coil did not warm enough, and the control got no signal back from the defrost circuit at the start. Left alone, frost can keep building on the coil. Sub-Zero Repair Redmond traces the heater circuit; call (425) 905-2822.
| Means | Defrost under-heat, together with no feedback from the defrost circuit when defrost started. |
|---|---|
| Check first |
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| Needs a technician |
|
Two faults in one code
EC 20 joins two conditions. Under-heat: the defrost heater did not bring the freezer coil up to temperature. No feedback: as defrost began, the control expected a signal back from the heater circuit and did not receive it. The same table keeps EC 22 for missing feedback alone and EC 24 for under-heat alone, so EC 20 is the case where both happen together.
What a working defrost does
The 600 Series freezer defrosts as needed. A heater warms the coil, the melt runs down to the water pan, and a terminator switch cuts out at 55°F (70°F on the 601F-3) to end the heat. When the heater circuit fails, frost stays on the coil and less air gets through it, and the freezer slowly warms.
Why the five minutes matter
In Sub-Zero’s test, a compressor that restarts five minutes into a manual defrost means the defrost ended early. That sends the technician to the wire carrying the heater’s signal back to the board before any part is replaced.
EC 20 on your display?
Sub-Zero Repair Redmond · $89 service call, deducted once the repair goes ahead · on site 0800 to 2000 hrs, all seven days
- Checked by
- Dean Halvorsen
- Bench
- sealed systems and airflow
- Trade
- 19 yrs
- Card
- EPA 608 certified
- Revised
