Sub-Zero BI/Designer Code 20-2-06: Bi-metal miswire with overheat

What 20-2-06 means

Here the control on a Classic BI unit such as the BI-36U/S, or on a Designer column like the DET3050CI, has found a miswired defrost bi-metal together with an overheat. The BI logs it for the freezer and the Designer for Zone 2. Because the bi-metal is wired wrong, the heater was not cut off on time and the evaporator area got too warm. You may hear dripping, find water under the freezer floor, notice soft ice cream, or smell warm plastic near the back wall.

Common causes of 20-2-06

Miswired bi-metal that fails to stop the defrost heater
Heater left energized long enough to overheat the evaporator area
Heat damage to the harness or nearby plastic that must be inspected

✓ One safe check you can try

1. Move ice cream and other heat-sensitive items to a backup freezer if you have one. 2. Wipe up any water that has collected so it does not refreeze around the door. 3. If you smell hot plastic, switch off the breaker and keep it off until we arrive. 4. Otherwise keep the door closed and do not try to clear the display repeatedly.

! Why to stop there

An overheat means the heater ran unchecked, so wiring and liners need a close look.
Restarting a miswired circuit can repeat the overheat.
Correct wiring must be confirmed against the diagram and with a monitored 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.

→Same appliance

Other Refrigerator codes

23Sub-Zero 600, 700 and 648PRO Code 23: Defrost overheat with no feedback 50Sub-Zero 600 and 700 Series Code 50: Refrigerator compressor running too long 41Sub-Zero 648PRO Code 41: Zone compressor or wiring problem 81Sub-Zero 700-2 Code 81: Variable-Speed compressor fails to start 82Sub-Zero 700-2 Code 82: VS compressor controller needs replacement 88Sub-Zero 700TF Code 88: Board and compressor controller not talking 80Sub-Zero 700TF Code 80: No inverter feedback after a board change ddSub-Zero 600 and 700 Series Display dd: Diagnostics switched off

20-2-0620-2-06 questions

How is 20-2-06 different from 20-2-05?

Both mean the defrost bi-metal is miswired. With 20-2-05 temperatures stayed normal; with 20-2-06 the control also saw an overheat, so the heater stayed on too long. That makes 20-2-06 the more urgent call.

Should I turn the unit off?

If there is a hot or burnt smell, yes, turn off the breaker. If not, leaving it running keeps the food cold, and we can usually schedule a prompt visit to correct the wiring before more heat builds up.

Will you replace parts that got too hot?

We inspect the heater, bi-metal, harness and nearby plastic, then list everything on a written price before work starts. Anything we repair is backed by our 30-day workmanship warranty.