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Frigidaire Refrigerator Error Code DEFROST SENSOR OF R ROOM

Refrigerator Defrost Sensor Error

Frigidaire codesFrigidaire refrigerator codes

Refrigerator Defrost Sensor Error - open or short-circuit, connector failure, or temperature reading greater than 122°F or less than -58°F.

First step from the service manual

Check the voltage at MAIN PCB Sensor between 4.5V~1.0V.

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

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What DEFROST SENSOR OF R ROOM means on a Frigidaire refrigerator

The DEFROST SENSOR OF R ROOM error indicates a fault in the refrigerator compartment defrost sensor circuit. This sensor monitors the temperature of the evaporator during the defrost cycle to prevent overheating and to signal when the evaporator has been sufficiently defrosted. The error triggers when the control board detects an open circuit, a short circuit, a connector failure, or a temperature reading that falls outside the acceptable range of -58°F to 122°F. Any of these conditions cause the main PCB to flag the sensor as unreliable or non-functional.

The defrost sensor is a thermistor, meaning its resistance changes in response to temperature. The main PCB supplies a reference voltage to the sensor and reads the return signal to calculate temperature. Normal operation produces a voltage at the sensor connector between approximately 1.0V and 4.5V. A reading at or near 0V typically indicates a short circuit, while a reading near the full supply voltage suggests an open circuit or a broken wire. Both extremes push the temperature calculation outside the -58°F to 122°F operational window and trigger this fault.

Connector corrosion or loose terminals at the sensor plug are a frequent cause of intermittent or persistent faults, particularly in environments with moisture exposure near the evaporator. If the connector checks out, the sensor itself should be tested for correct resistance at a known temperature. If wiring and the sensor both pass inspection, the main PCB may be misreading the signal and could require replacement.

Source: manufacturer service documentation.

Common causes of DEFROST SENSOR OF R ROOM

  1. 01

    Faulty Defrost Sensor (Thermistor)

    Part replacement

    The thermistor itself may have failed internally, causing an open or short circuit. Testing resistance at the sensor terminals will reveal whether it falls outside the expected range for the current temperature.

  2. 02

    Loose or Corroded Connector

    Wiring / connection

    The connector between the defrost sensor and the wiring harness can develop corrosion or lose contact, especially near the evaporator where moisture is present. Inspect the connector pins for oxidation, bending, or looseness and reseat or clean as needed.

  3. 03

    Damaged Wiring Harness

    Part replacement

    The wires running between the sensor and the main PCB can become pinched, chafed, or broken during normal use or a previous repair. A visual inspection and continuity test along the harness will identify any breaks or shorts.

  4. 04

    Out-of-Range Temperature Condition

    Wiring / connection

    If the refrigerator compartment temperature has risen above 122°F or dropped below -58°F due to a separate fault, the sensor may be reading accurately but the reading itself triggers the error. Verify the actual compartment temperature with an independent thermometer.

  5. 05

    Failed Main PCB

    Part replacement

    If the sensor voltage at the main PCB connector does not fall between 1.0V and 4.5V despite a good sensor and intact wiring, the control board may be supplying incorrect reference voltage or misreading the signal. Board replacement is a last resort after all other components are confirmed good.

See the test procedure for each cause

Frequently asked questions about DEFROST SENSOR OF R ROOM

What does DEFROST SENSOR OF R ROOM mean on a Frigidaire refrigerator?
This error means the main control board has detected a problem with the defrost sensor in the refrigerator compartment. The fault can be caused by an open or short circuit in the sensor, a connector failure, or a temperature reading outside the accepted range of -58°F to 122°F. The board reads a voltage between 1.0V and 4.5V from the sensor under normal conditions, and any reading outside that window triggers the alert.
Can I fix the DEFROST SENSOR OF R ROOM error myself?
A knowledgeable DIYer can diagnose this error by checking the sensor connector for corrosion or loose pins and measuring the voltage at the main PCB sensor terminal with a multimeter. If the voltage is outside the 1.0V to 4.5V range, the next step is testing or replacing the thermistor. Wiring repairs and board replacements are more involved and may be better suited to a technician.
Is it safe to keep using my refrigerator while this error is active?
A defrost sensor fault can prevent the defrost cycle from running correctly, which may lead to frost accumulating on the evaporator over time. Heavy frost buildup will eventually restrict airflow and reduce cooling performance. It is best to address the error promptly to avoid food spoilage or secondary component damage.
How much does it cost to repair a defrost sensor error on a Frigidaire refrigerator?
If only the thermistor needs replacement, parts typically cost in the range of $15 to $50 depending on the specific model. If a technician is needed for diagnosis and labor, total repair costs generally range from $100 to $250. A main PCB replacement, if required, can push costs higher, typically in the $150 to $400 range for parts and labor combined.
Will resetting my Frigidaire refrigerator clear the DEFROST SENSOR OF R ROOM error?
A reset may temporarily clear the error code, but if the underlying fault still exists, the error will return once the control board runs its diagnostic check again. Resetting without repairing the sensor, wiring, or connector does not resolve the problem. A permanent fix requires identifying and correcting the root cause before the code will stay cleared.

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