E18 error, unit fails to defrost properly, heavy ice buildup on evaporator

Safety first: Unplug the ice maker. Defrost heaters operate at mains voltage and can be hot.

• Manual defrost: Open the unit and allow it to defrost completely by leaving it unplugged with the door open. Use towels to collect melt water. Do not use sharp tools to remove ice.
• Locate defrost components: Access the evaporator area and identify the defrost heater (often a metal or glass tube) and defrost thermostat or sensor clipped to the coil.
• Test heater: Disconnect the heater and measure resistance. An open circuit indicates a failed heater that must be replaced.
• Test thermostat/sensor: Check continuity of the defrost thermostat when cold. For electronic sensors, compare resistance to the service chart. Replace if faulty.
• Inspect wiring and board: Ensure all connectors are secure. If heater and thermostat are good, the control board may not be initiating defrost and will need replacement.
• Reassemble and monitor: After replacing components, reassemble and run the unit. Monitor for several days to ensure ice does not build up again.