Sub-Zero Refrigerator Freezer Error Codes – How to fix? by KnRepair.com
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HOW TO USE THE ERROR CODE TROUBLESHOOTING GUIDE
Error Codes indicate problems registered by specific components. If error codes are registered, they will appear before temperature readings while in Diagnostic Mode.
NOTE: If Error Codes appear with a flashing “SERVICE” annunciator prior to initiating Diagnostic Mode, the unit experienced excessive compressor run condition that may or may not be associated with the Error Codes displayed
To initiate Diagnostic Mode, press and hold either COLDER key, then press the POWER key, then release both keys. Now, check to see if Error Codes are present, being sure to toggle through all error and temperature readings by pressing either COLDER key or either WARMER key. (See Error Code Table Below)
If Error Codes appear during Diagnostic Mode, follow the Error Code Troubleshooting Guide on the following page. The left column of the troubleshooting guide lists the error codes. The information in the right column explains what tests to perform and/or what action to take to correct the error.
NOTE: If error codes are observed in diagnostic mode, a non-flashing SERVICE annunciator will appear on the LCD when Diagnostic Mode ends, indicating error codes are still stored. Error Codes must be cleared from the electronic control memory manually. To clear the non-flashing SERVICE annunciator and the error codes, the problem must be corrected and the unit must be ON, then:
• On a model UC-24C: Press the Freezer WARMER and COLDER keys for fifteen (15) seconds.
• On a model UC-24B, UC-24R, or UC-24RO: Press the Refrigerator WARMER and COLDER keys for fifteen (15) seconds
Error Code Table
| CODE | INDICATION |
| 05 | Refrig. cabinet thermistor read open or shorted for 10+ seconds, or repeatedly read erratic temp’s |
| 06 | Refrig. evaporator thermistor read open or shorted for 10+ seconds, or repeatedly read erratic temp’s |
| 07 | Freezer cabinet thermistor read open or shorted for 10+ seconds, or repeatedly read erratic temp’s |
| 08 | Freezer evaporator thermistor read open or shorted for 10+ seconds, or repeatedly read erratic temp’s |
| 20 | Defrost under-heat with no voltage feedback through Gray/White wire at defrost start |
| 21 | Defrost overheat |
| 22 | No voltage feedback through Gray/White wire at defrost start |
| 23 | Defrost overheat with no voltage feedback through Gray/White wire at defrost start |
| 24 | Defrost under-heat |
| 30 | N/A |
| 40 | Excessive Freezer Compressor Run |
| 50 | Excessive Refrigerator Compressor Run |
| Error Code | CAUSE | SOLUTION |
| Error Code 80 | High variable speed compressor differential pressures or low voltage supplied to variable speed compressor | Inspect the suction pressure and return the suction pressure to normal levels. |
Error Code 80
A. If “EE” for refrigerator compartment was displayed and “SERVICE” flashing, check the following:
1. Thermistor electrical connections and continuity from thermistor to J5 on control board. Reconnect / repair.
2. Resistance of thermistor – 30,000 to 33,000 ohms at 32°F (0°C). Replace if defective.
B. If “EE” for refrigerator compartment was NOT displayed, problem is intermittent thermistor error:
1. Door not closing properly. Correct door closing problem.
2. Check light switch, wiring & electrical connections. Repair wiring / connections or replace switch.
3. Check thermistor electrical connections and continuity at J5 on control board. Reconnect / repair.
4. Check resistance of thermistor – 30,000 to 33,000 ohms at 32°F (0°C). Replace if defective.
C. If “EC 05” and “SERVICE” were flashing before initiating diagnostic mode, unit also experienced excessive compressor run condition that may or may not be associated with the “05” Error Code. See Error Code 50 Test/Actions.
