Diagnostic mode shows E3 and defrost cycles are irregular, with either heavy frost or excessive defrosting.

Safety first: Unplug the refrigerator before removing the freezer rear panel.

• Access evaporator: Remove freezer shelves and the rear panel to expose the evaporator coil.
• Locate thermistor: The evaporator thermistor is clipped to the coil tubing. Ensure it is firmly attached and not hanging loose.
• Test thermistor: Disconnect and measure resistance at a known temperature. Replace if readings are out of range.
• Inspect wiring: Look for brittle, cracked, or corroded wires and connectors. Repair or replace as needed.
• Control board: If a new thermistor does not clear E3, the main control board may be defective.