Display shows F4; ice buildup may be present on the evaporator, and cooling performance is poor.

Safety: Unplug the refrigerator before working inside the freezer or near wiring.

F4 indicates the evaporator sensor is not reading correctly, which can affect defrost control.

• Access evaporator area: Remove freezer drawers and the rear interior panel to expose the evaporator cover. Be careful not to damage foam insulation.
• Check sensor position: The evaporator thermistor is usually clipped to the evaporator tubing. Ensure it is firmly attached and not hanging loose or embedded in thick ice.
• Defrost if iced over: If the evaporator is a solid block of ice, perform a manual defrost by leaving the unit unplugged with doors open until all ice melts. Place towels to catch water.
• Inspect wiring: Look for brittle, cracked, or broken wires around the evaporator area. Moisture can corrode connectors; clean and reseat them.
• Test and replace: With the sensor disconnected, measure resistance at the current evaporator temperature and compare to spec. Replace the evaporator thermistor if readings are open, shorted, or far off expected values.
• Reassemble and test: Refit the evaporator cover and drawers, restore power, and monitor for recurrence of F4. If the code returns, the control board may need replacement by a professional.