Display shows E4; refrigerator may not defrost properly, leading to frost buildup on the evaporator.

Safety: Unplug the refrigerator before accessing the evaporator area. Beware of sharp fins and edges.

• Check for frost: Remove the freezer rear interior panel and inspect the evaporator. A solid block of ice indicates a defrost system problem.
• Locate defrost sensor: The defrost thermistor is usually clipped to the evaporator tubing near the top.
• Inspect sensor: Look for cracks in the sensor body, broken wires, or loose clips.

If the E4 code is present and the sensor appears damaged, replace the defrost thermistor. If the sensor looks intact, it should be tested with an ohmmeter; if readings are out of range, replace it. Persistent issues may indicate a control board problem.