Display shows E4 and the unit may not defrost properly, with ice buildup on the evaporator.

Safety first: Unplug the cooler. Be cautious of sharp evaporator fins.

• Inspect for frost: Remove interior shelves and back panel inside the compartment to expose the evaporator coil. Look for heavy ice buildup.
• Locate defrost/evaporator sensor: Find the small sensor clipped to the evaporator tubing or mounted near the coil.
• Check wiring: Inspect the sensor leads for breaks or insulation damage caused by ice. Ensure the sensor is firmly clipped to the coil.
• Defrost manually: Allow the unit to sit unplugged with doors open for several hours until all ice melts. Use towels to catch water; do not use heat guns or open flames.
• Replace sensor: If the sensor looks damaged or E4 returns after defrosting, replace the evaporator/defrost temperature sensor.
• Control board check: If a new sensor does not resolve E4 and defrost cycles never occur, the main control board may need replacement.