Error code F4 appears; defrost cycles seem abnormal and frost may build up on the evaporator.

Safety first: Unplug the appliance. Wear cut-resistant gloves when working near evaporator fins.

Step-by-step:

• Access evaporator: Remove freezer drawers and the rear inner panel to expose the evaporator coil.
• Locate defrost sensor: The defrost NTC is typically clipped to the evaporator tubing or attached with a metal clip or bracket.
• Check mounting: Ensure the sensor is firmly attached to the coil. If it has fallen off, reattach it securely using the original clip or a new one.
• Inspect wiring: Look for brittle or cracked insulation, especially where the cable exits the foam insulation.
• Test sensor: Disconnect and measure resistance. Compare to expected NTC values at freezer temperature. Replace if open, shorted, or far out of spec.
• Reassemble and test: Refit the panel, restore power, and monitor for proper defrosting over the next 24–48 hours. The F4 code should clear automatically on many models.