Kenmore Refrigerator Error Code rd

The rd error code on a Kenmore refrigerator indicates that the refrigerator defrost sensor is reading as either open or shorted. The defrost sensor is a thermistor-based component that monitors the temperature of the evaporator coil during and after defrost cycles. The main PCB relies on this sensor to determine when the evaporator has reached the target defrost temperature and to terminate the defrost heater cycle safely. When the PCB receives a signal outside the expected resistance range, it interprets the sensor as either open (broken circuit, infinitely high resistance) or shorted (near-zero resistance), triggering the rd fault.

An open sensor condition typically means the thermistor element itself has failed internally, or a wiring break has occurred somewhere between the sensor and the main PCB. A shorted condition usually points to a failed thermistor that has collapsed to near-zero resistance, or to a wiring harness fault where two conductors are making unintended contact. Either condition prevents the control board from accurately reading evaporator temperature, which can cause the defrost heater to run unchecked or not at all, leading to frost buildup or potential overheating of the evaporator compartment.

The first diagnostic step is to inspect all wiring connections between the defrost sensor and the main PCB. Loose, corroded, or damaged connector pins are a frequent cause of this fault, and can produce intermittent or permanent open-circuit readings without the sensor itself being defective. If the wiring checks out, the sensor's resistance should be measured and compared against the expected value for the current evaporator temperature to determine whether the thermistor has failed.