Freezer shows E4 and may stop cooling correctly; sometimes accompanied by irregular defrost cycles.

Warning: High voltage components are involved. Unplug the freezer before any work. If you are not comfortable with electrical testing, contact a professional.

• Check for frost buildup: If the rear internal panel is covered in thick ice, the defrost heater may not be working.
• Access the evaporator and heater: Remove drawers and the inner rear panel to expose the evaporator. The defrost heater is usually a metal or glass-encased element at the base or woven through the evaporator.
• Visual inspection: Look for burnt spots, broken heater tubes, or melted connectors.
• Test heater resistance: Disconnect the heater connectors and measure resistance with a multimeter. A typical Balay defrost heater may read between 50–300 Ω depending on model. An open circuit (OL) indicates a failed heater.
• Check thermal fuse (if present): Some Balay freezers include a thermal fuse in series with the heater. Test for continuity; replace if open.
• Replace faulty components: Install a new Balay defrost heater assembly (and thermal fuse if separate). Ensure all connections are tight and properly insulated.
• Reassemble and test: Refit the panel, restore power, and monitor for normal defrost operation and disappearance of the E4 code over several hours of operation.

If the heater and fuse are good, the defrost relay or main PCB may be defective and should be checked by a technician.