Sub-Zero error code · 20 2 00
Sub-Zero Code 20 2 00: Defrost Bi-Metal Stuck Open
Sub-Zero code 20 2 00 means the defrost bi-metal is stuck open. Verify it is open below 40F, then replace the defrost bi-metal thermostat if faulty.
Sub-Zero code 20 2 00 means the defrost bi-metal (defrost termination thermostat) is stuck open. Verify the bi-metal reads open circuit below 40F (4C), and replace the defrost bi-metal if it is faulty.
20 2 00, explained
The defrost bi-metal is a temperature-sensing switch on the evaporator that tells the board the coil temperature during the defrost cycle and limits the defrost heater. With this fault the board sees the bi-metal open when it expects continuity, indicating it is stuck open. Sub-Zero directs verifying the bi-metal is open below 40F and replacing it if necessary.
Severity:Service recommended · Service light:ON
How 20 2 00 shows up
- SERVICE light on
- Frost or ice buildup on the freezer evaporator coil
- Warming freezer or refrigerator as airflow over the iced coil drops
- Longer run times and reduced cooling capacity
- Fault code 20 2 00 stored or shown in service mode
What usually causes it
- Defrost bi-metal failed open internally
- Corroded or broken terminal at the bi-metal
- Damaged or disconnected wiring to the bi-metal
- Bi-metal not making proper thermal contact with the evaporator
Which part 20 2 00 points to
- Defrost bi-metal (defrost termination thermostat) — Replace if it does not read open circuit below 40F (4C) as specified, or is otherwise faulty
Why 20 2 00 appears
Bi-metal switches fatigue from thousands of heat-and-cool cycles and can fail permanently open. Corrosion on the terminals, broken internal contacts, frost intrusion, and aging connections all contribute. A loose or damaged wire to the bi-metal can also present as an open circuit.
What you can safely check
- Power the unit off at the breaker for two minutes, then restore power to see if the code clears
- Note any frost buildup on the freezer coil area and warming compartments
- Confirm doors seal fully so excess frost is not from a door left ajar
- Record the exact code for the technician
When 20 2 00 needs a technician
Verifying the bi-metal opens below 40F and replacing it requires accessing the sealed evaporator area and ohm-testing the switch, which a technician should perform.
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Frequently asked
Sub-Zero 20 2 00 — questions
What does Sub-Zero code 20 2 00 mean?
Code 20 2 00 means the defrost bi-metal, also called the defrost termination thermostat, is stuck open. This switch sits on the freezer evaporator and tells the board the coil temperature during defrost while limiting the defrost heater. When the board sees it open at a point where it expects continuity, it flags the bi-metal as stuck open and turns on the SERVICE light.
How does a technician confirm a 20 2 00 fault?
The defrost bi-metal should read open circuit below 40F (4C). A technician accesses the evaporator area and ohm-tests the switch at that temperature; if it does not behave as specified, or a terminal is corroded or a wire is broken, the bi-metal is replaced. The verification step matters because a damaged wire to the bi-metal can mimic the same open reading.
How is 20 2 00 different from 20 2 01?
They are opposite failures of the same defrost bi-metal. 20 2 00 is stuck open, verified by reading open below 40F, while 20 2 01 is stuck closed, verified by remaining closed above 70F (21C). The stuck-open case in 20 2 00 tends to leave frost building on the coil because the defrost logic is disrupted.
Can I clear 20 2 00 myself or is this a DIY fix?
You can power the unit off at the breaker for about two minutes and check whether the code clears, confirm the doors seal fully so frost is not from a door left ajar, and note any coil frost for the technician. The actual repair is not DIY, since it requires reaching the sealed evaporator area and ohm-testing the switch.
Is it safe to keep using the unit with 20 2 00?
It is a medium-urgency fault. The unit keeps running, but a stuck-open bi-metal lets frost and ice build on the freezer evaporator coil, which reduces airflow and can warm both compartments over time while run times climb. It will keep cooling short term, but you should schedule service before the icing worsens.
What part is replaced for 20 2 00 and what does it cost?
The part is the defrost bi-metal (defrost termination thermostat), replaced if it does not read open below 40F as specified or is otherwise faulty. We charge a flat $89 diagnostic to verify the switch, back the repair with a 365-day warranty, and you can reach us at (650) 668-1554 to schedule.
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