Service mode shows F4; defrost cycle does not terminate correctly.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Open defrost heater, Failed defrost thermostat, Broken heater wiring, Main control board defrost relay failure

Safety first: Unplug the refrigerator before testing heater circuits.

Access heater: Remove the freezer rear panel to expose the evaporator and heater assembly.
Visual check: Look for burnt spots or breaks in the heater element.
Continuity test: Disconnect heater leads and test for continuity. Replace the heater if open.
Check thermostat: Test the defrost thermostat for continuity when cold; replace if open.
Control board: If heater and thermostat are good, the control board may not be energizing the heater and should be evaluated.

Hard 4/5

Defrost Heater

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