Sub-Zero Designer Code 10-2-10: Zone 2 evaporator thermistor open

What 10-2-10 means

On current Sub-Zero Designer units such as the DET3050CI and DEC3050R, 10-2-10 means the zone 2 evaporator thermistor is reading open. Some Designer listings call it the zone 2 second device open, which refers to the same sensor on the coil. The control uses this reading to decide when the zone 2 coil needs defrosting. With an open circuit it cannot see the coil temperature, so frost may build up and cooling in that zone can slowly weaken.

Common causes of 10-2-10

Evaporator thermistor in zone 2 open
Broken wire between the coil sensor and the control
Connector pulled apart at the evaporator area

✓ One safe check you can try

1) Check the zone 2 rear panel for heavier frost than usual. 2) Keep that zone closed to limit moisture. 3) Do not scrape or chip at frost. 4) Turn power off at the breaker briefly and restore it. 5) Schedule service if the code stays or temperatures rise.

! Why to stop there

The evaporator sensor is clipped to the coil behind the rear cover.
The coil may need thawing before anyone can reach the sensor.
Correct placement on the coil matters for accurate defrost.

Opening a panel yourself does not automatically cancel a manufacturer warranty, but it can cause accidental damage, and some manufacturers set their own service conditions. Check your warranty terms, or ask us, before deciding.

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Other Refrigerator codes

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10-2-1010-2-10 questions

What is the second device in zone 2?

On Designer units the evaporator thermistor is the second sensor in a zone, after the cabinet sensor. Code 10-2-10 means that coil sensor reads as open, so the control has no coil temperature.

Will zone 2 still cool?

Often for a while, but defrost timing suffers without the coil reading. Frost can gradually block airflow, so book service before zone 2 starts warming noticeably.

How is it fixed?

We thaw the coil if needed, test the evaporator thermistor and wiring, and replace or repair it. You get a written price first, and once the sensor is back in place we confirm zone 2 completes a normal defrost.