Display shows E3 and the freezer may not defrost properly, leading to ice buildup on the evaporator and poor cooling.

Safety first: Disconnect power before accessing the evaporator or heater. Avoid contact with sharp fins and hot components.

Access defrost components:

• Remove drawers and the rear interior panel to expose the evaporator.
• Locate the defrost thermostat (a small round or oval device clipped to the evaporator tubing) or a dedicated defrost NTC sensor, depending on model.

Visual inspection:

• Check for heavy ice buildup around the thermostat or sensor.
• Inspect wiring for brittleness, burn marks, or broken insulation near the defrost heater.

Test the thermostat/sensor:

• For a mechanical thermostat: With the evaporator cold and frosted, disconnect the thermostat and measure continuity. It should show continuity (closed) when cold. Warm it gently with your hand or a hair dryer (on low, at a distance) and verify it opens (no continuity).
• For an NTC-type defrost sensor: Disconnect and measure resistance; compare to expected NTC values. Open or short readings indicate failure.

Corrective actions:

• Defrost manually: If the coil is heavily iced, allow the unit to defrost fully (doors open, towels in place) for several hours before further testing.
• Replace faulty sensor/thermostat: Install a Blomberg-compatible defrost thermostat or NTC. Clip it firmly to the evaporator tube in the original position.
• Inspect heater and wiring: While exposed, visually check the defrost heater and wiring for damage. Repair any obvious broken wires using proper crimp connectors and heat-shrink tubing.
• If the sensor and wiring are good but E3 persists, the main control board defrost circuit may be defective and require replacement.

Test: Reassemble, restore power, and force a defrost cycle if your model allows (refer to service documentation). Monitor for correct defrosting and absence of E3 over several days.