Kenmore Refrigerator Error Code F3

The F3 error code on a Kenmore refrigerator indicates a freezer defrost heater fault in which the automatic defrost cycle was unable to complete normally and instead timed out after reaching the 70-minute limit. Under normal operation, the defrost cycle is terminated by the defrost termination thermostat or sensor once the evaporator coils reach a target temperature. When the system hits the 70-minute cutoff instead, it signals that either the heater did not generate enough heat or the sensor failed to detect that defrosting was complete.

The two primary components involved are the defrost heater element and the defrost sensor. The defrost heater is responsible for melting frost accumulation off the evaporator coils. If the heater has failed open circuit, it will produce no heat at all, forcing the control board to terminate the cycle by time. The defrost sensor monitors coil temperature and signals the board when defrost is complete. A sensor that reads incorrectly or has failed can prevent a proper temperature-based termination, again causing a timeout.

Common contributing factors include a burned-out heater element, a defrost sensor with a resistance value outside the expected range for the current temperature, wiring harness damage, or a failed defrost relay on the control board. Ice buildup that has become excessive over time can also extend defrost duration beyond the 70-minute threshold. Diagnosis should begin by inspecting and testing the defrost heater for continuity and checking the defrost sensor for appropriate resistance output.