Freezer displays E4 and may not defrost properly, with ice building up on the evaporator and rear panel.

Safety warning: Disconnect mains power before accessing the evaporator or defrost components. Beware of sharp metal edges and ice.

Steps to resolve E4 (defrost sensor/thermostat):

• 1. Defrost the unit: Empty the freezer and allow it to defrost fully (doors open, towels to catch water). Do not chip ice with sharp tools to avoid damaging the evaporator.
• 2. Access the evaporator area: Remove the inner rear panel to expose the evaporator coil and defrost components.
• 3. Identify defrost components: New World freezers typically use either an NTC defrost sensor clipped to the evaporator or a bi‑metal defrost thermostat attached to the coil, plus a defrost heater.
• 4. Check wiring and connectors: Inspect the harness from the defrost sensor/thermostat to the main PCB. Look for broken wires, burnt connectors, or signs of overheating.
• 5. Test the defrost sensor/thermostat:
  • For an NTC sensor: Measure resistance at around 0–10°C (slightly cool). Compare to the expected NTC value. Open or short readings indicate failure.
  • For a bi‑metal thermostat: At room temperature (after defrost), it may be open; test continuity when cooled (e.g., with an ice pack). If it never closes, it is faulty.
• 6. Replace faulty parts: Install a new New World defrost NTC sensor or defrost thermostat (bi‑metal) as per your model. Clip it securely to the evaporator tubing in the same position.
• 7. Inspect the defrost heater: While accessible, visually check the defrost heater for breaks or burn marks and test for continuity. Replace if open circuit.
• 8. Reassemble and test: Refit the rear panel, restore power, and monitor for E4 clearing and normal frost pattern over several hours.

Note: If all defrost components test good, the main control PCB may not be initiating defrost correctly and may need replacement.