Kenmore Refrigerator Error Code R1 R4 ON

The R1 R4 ON code indicates that the defrost sensor has been detected with an open circuit or a short circuit condition. The control board monitors the resistance of the defrost thermistor to manage defrost cycles, and this code appears when the reading falls outside a valid range. This can cause the defrost system to stop functioning correctly, potentially resulting in frost buildup on the evaporator coil.

A reset may temporarily clear the code from the display, but the fault will return if the underlying sensor or wiring problem is not repaired. The control board will re-run its diagnostics and re-trigger the code as long as the defrost sensor circuit reads an invalid value. A reset alone is not a fix.

If only the defrost sensor 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 installation, total repair costs including labor generally fall in the range of $100 to $250. Control board replacement, if required, would increase costs significantly above that range.

Start by locating the defrost sensor in the evaporator compartment and disconnecting its wiring connector. Use a multimeter to measure resistance across the sensor terminals. If the reading is infinite or near zero, the sensor needs to be replaced. Also inspect the wiring harness and connector for damage or corrosion before ordering parts.

The refrigerator may continue to cool for a period of time, but a non-functioning defrost sensor means the defrost cycle cannot operate correctly. Over time, ice will accumulate on the evaporator coil and block airflow, leading to a gradual loss of cooling. It is best to address the fault promptly to avoid food spoilage.