Freezer displays E4 and may not defrost; heavy ice build‑up on evaporator and rear panel

Safety warning: Unplug the freezer before testing the heater. The defrost heater operates at mains voltage.

Steps to diagnose and fix E4:

• 1. Access the evaporator and heater: Remove drawers and the internal rear panel. Carefully defrost any heavy ice with warm air (hairdryer on low, kept at a safe distance) and towels.
• 2. Locate the defrost heater: It is usually a metal or glass‑encased element running along the bottom or woven through the evaporator.
• 3. Visual inspection: Look for burn marks, broken element sections, or melted connectors.
• 4. Test heater resistance: Disconnect the heater leads and measure resistance with a multimeter. A typical reading is between 50–300 Ω depending on model. An open circuit indicates a failed heater.
• 5. Check thermal fuse (if fitted): Some Caple freezers include a thermal fuse in series with the heater. Test for continuity; replace if open.
• 6. Replace faulty heater: Remove mounting clips or screws, fit the new heater in the same position, and reconnect wiring firmly. Keep wiring away from sharp fins.
• 7. PCB/relay check: If the heater and fuse are good, the defrost relay or triac on the main control PCB may be faulty. This typically requires PCB replacement.

Note: After repair, allow the freezer to run for 24 hours and check that frost build‑up is reduced and E4 does not reappear.