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Error code reference

Amana Refrigerator Error Code Open Thermistor Detect

If freezer or refrigerator thermistor circuit is open, wiring to them is open, or low voltage board fails…

Amana codesAmana refrigerator codes

If freezer or refrigerator thermistor circuit is open, wiring to them is open, or low voltage board fails, the freezer or refrigerator indicator lights 4 through 7 will sequence until Alarm Off is pressed.

First step from the service manual

Check thermistor resistance values and wiring continuity to thermistors and low voltage board.

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

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  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
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What Open Thermistor Detect means on a Amana refrigerator

The Open Thermistor Detect error on an Amana refrigerator signals that the control system has detected an open circuit condition in one or both thermistor circuits. Thermistors are temperature-sensing resistors whose resistance values change predictably with temperature. When the circuit reading falls outside the expected resistance range, the board interprets this as an open circuit, meaning the electrical path is broken somewhere between the thermistor itself and the low voltage control board. The refrigerator and freezer compartment indicator lights 4 through 7 will sequence in a repeating pattern to alert the user, and this visual alarm continues until the Alarm Off button is pressed.

The fault can originate from three distinct sources: the thermistor itself, the wiring harness connecting the thermistor to the board, or the low voltage board. A thermistor that has failed internally will show an infinite or out-of-range resistance reading when tested with a multimeter. Wiring faults such as a broken wire, corroded connector, or damaged harness insulation can interrupt the circuit just as effectively as a failed sensor. If both the thermistor and wiring check out correctly, the low voltage board itself may have failed and is no longer accurately processing the incoming thermistor signal.

Diagnosing this code requires a systematic approach starting with resistance measurement at the thermistor terminals and then verifying continuity through the wiring harness all the way to the low voltage board connector. Temperature and expected resistance values for the thermistors should guide the interpretation of any readings taken. A reading of infinite resistance at any point in the circuit confirms an open condition at that location and narrows the repair to that specific component or section of wiring.

Source: manufacturer service documentation.

Common causes of Open Thermistor Detect

  1. 01

    Failed thermistor

    Part replacement

    The thermistor itself has failed internally, resulting in an open circuit and an out-of-range or infinite resistance reading when tested with a multimeter. Replacing the faulty thermistor is typically required.

  2. 02

    Broken or damaged wiring harness

    Wiring / connection

    A wire in the harness running between the thermistor and the low voltage board may be broken, frayed, or corroded at a connector, interrupting the circuit. Inspect the full length of the wiring and test continuity at each section.

  3. 03

    Corroded or loose connector

    Wiring / connection

    Moisture inside the refrigerator cabinet can corrode connector terminals, creating an open or high-resistance connection even if the thermistor and wiring are otherwise intact. Cleaning or reseating the connector may resolve the fault.

  4. 04

    Low voltage board failure

    Part replacement

    If the thermistor resistance and wiring continuity both test correctly, the low voltage board may have failed and is no longer processing the thermistor signal accurately. Board replacement is required in this case.

See the test procedure for each cause

Frequently asked questions about Open Thermistor Detect

What does Open Thermistor Detect mean on a Amana refrigerator?
This error means the control system has detected an open circuit in the freezer or refrigerator thermistor circuit. The thermistor is a temperature sensor that sends resistance-based readings to the low voltage board so the refrigerator can regulate cooling. When that circuit is broken due to a bad sensor, damaged wiring, or a failed board, indicator lights 4 through 7 will sequence as a warning alert.
How do I fix the Open Thermistor Detect error on my Amana refrigerator?
Start by checking the resistance values at each thermistor with a multimeter and comparing them to the expected range for the current cabinet temperature. Next, test the wiring harness for continuity from the thermistor connectors all the way to the low voltage board. If the thermistor reads open or infinite resistance, replace it. If the wiring is broken or corroded, repair or replace the affected section. If both components test correctly, the low voltage board may need to be replaced.
Will pressing Alarm Off fix the Open Thermistor Detect error?
Pressing Alarm Off will stop the sequencing indicator lights and silence the visual alert, but it does not fix the underlying fault. The error will return if the open circuit condition in the thermistor wiring or the board is not corrected. The Alarm Off button is intended to acknowledge the alert, not to clear the root cause.
Is it safe to keep using my Amana refrigerator when this error is showing?
Continued use carries some risk because the control board may not be able to accurately monitor or regulate internal temperatures without a functioning thermistor circuit. Food safety could be compromised if the refrigerator or freezer drifts outside of safe temperature ranges without triggering the appropriate cooling response. It is best to address the repair promptly and monitor compartment temperatures with a separate thermometer in the meantime.
How much does it cost to repair an Open Thermistor Detect error on an Amana refrigerator?
Repair costs vary depending on which component has failed. A replacement thermistor is generally an inexpensive part, typically in the range of $15 to $50 for the part alone. Wiring repairs may cost little if only a connector needs cleaning, or more if a section of harness must be replaced. Low voltage board replacement is the most expensive scenario, with parts potentially ranging from $80 to $200 or more, plus labor if a technician performs the work.

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