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Error code reference

Norcold Refrigerator Error Code Temperature setting flashing

Thermistor detected as non-functional; backup operating system (BOS) is controlling temperature.

Norcold codesNorcold refrigerator codes

Thermistor detected as non-functional; backup operating system (BOS) is controlling temperature.

First step from the service manual

Check that the thermistor cable is plugged in; inspect for broken or dirty connections; measure thermistor resistance.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What Temperature setting flashing means on a Norcold refrigerator

When the temperature setting display is flashing on a Norcold refrigerator, it indicates that the thermistor has been detected as non-functional by the control board. The thermistor is a temperature-sensing resistor whose resistance value changes predictably with temperature. The control board continuously monitors this resistance to regulate cooling cycles. When the board reads a resistance value outside the expected range, or detects an open or short circuit in the thermistor circuit, it flags the sensor as failed and triggers the flashing display.

Once the thermistor is flagged as non-functional, the refrigerator switches to the Backup Operating System, commonly referred to as BOS. The BOS allows the unit to continue cooling without active thermistor feedback, but it operates on a fixed duty cycle rather than precise temperature-based control. This means the refrigerator is still running, but it cannot maintain temperature as accurately as it would under normal closed-loop thermistor control.

The most common entry points for this fault are connection issues rather than complete thermistor failure. The thermistor cable connector can become unplugged, corroded, or contaminated with moisture or debris, all of which can disrupt the resistance signal the board expects to read. A thorough inspection should start at the connector, checking for secure seating and clean contacts, before proceeding to measure the thermistor resistance directly with a multimeter to determine whether the sensor itself has failed.

Source: manufacturer service documentation.

Common causes of Temperature setting flashing

  1. 01

    Disconnected thermistor cable

    Wiring / connection

    The thermistor connector may have worked loose from vibration or during servicing. Check that the cable is fully and securely plugged into its socket on the control board and at the thermistor itself.

  2. 02

    Corroded or dirty connector contacts

    Wiring / connection

    Moisture, oxidation, or debris on the thermistor connector pins can interrupt or distort the resistance signal. Inspect the connector for visible corrosion, green deposits, or contamination and clean the contacts carefully.

  3. 03

    Broken or damaged thermistor wiring

    Wiring / connection

    The cable between the thermistor and the control board can develop breaks, chafing, or pinch points that interrupt continuity. Visually trace the wiring and use a multimeter to check for continuity along the harness.

  4. 04

    Failed thermistor

    Part replacement

    The thermistor itself may have failed internally, producing a resistance value that is out of range or reading as open or shorted. Measure the thermistor resistance with a multimeter and compare the reading to the expected value for the ambient temperature; a reading that is wildly out of range or infinite indicates a failed sensor.

  5. 05

    Faulty control board

    Part replacement

    If the thermistor and all wiring check out correctly but the fault persists, the control board may not be reading the sensor signal properly. This is the least common cause and should be considered only after the thermistor circuit has been fully verified.

See the test procedure for each cause

Frequently asked questions about Temperature setting flashing

What does Temperature setting flashing mean on a Norcold refrigerator?
A flashing temperature setting on a Norcold refrigerator means the control board has detected that the thermistor, the temperature sensor, is non-functional. In response, the unit has automatically switched to its Backup Operating System so it can continue cooling. The refrigerator is still running, but precise temperature regulation is not available until the thermistor issue is resolved.
How do I fix the flashing temperature setting on my Norcold refrigerator?
Start by checking that the thermistor cable is fully plugged in at both ends and that the connector contacts are clean and free of corrosion. If the connection looks good, use a multimeter to measure the thermistor resistance to determine whether the sensor itself has failed. If the sensor resistance is out of range, the thermistor will need to be replaced. If both the sensor and wiring test correctly, the control board may require further evaluation.
Is it safe to use my Norcold refrigerator when the temperature setting is flashing?
The refrigerator is still operating on the Backup Operating System and will continue to cool, so it is generally safe to use in the short term. However, because BOS runs on a fixed cycle rather than sensor-based feedback, the unit cannot maintain temperature as accurately as normal. Perishable foods should be monitored, and the thermistor issue should be diagnosed and corrected as soon as practical.
Will resetting the Norcold refrigerator clear the flashing temperature setting error?
A simple reset is unlikely to permanently clear this fault because the control board actively monitors the thermistor circuit and will re-detect the fault if the underlying problem has not been corrected. The flashing display will return unless the thermistor connection is secured, the wiring is repaired, or a failed thermistor is replaced.
How much does it cost to fix a flashing temperature setting error on a Norcold refrigerator?
If the fix is as simple as reseating a loose connector or cleaning dirty contacts, there may be no parts cost at all. If the thermistor itself has failed, replacement thermistors typically cost in the range of $15 to $60 depending on the specific model. If the control board is at fault, board replacement costs can range from $100 to $300 or more. A technician's diagnostic and labor fees will add to whichever parts cost applies.

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