Display shows E3 and refrigerator may run continuously or not defrost properly.

Safety first: Unplug the refrigerator and wear cut-resistant gloves when working around metal panels and coils.

Access the evaporator area:

• Empty the freezer compartment and remove shelves and drawers.
• Remove screws securing the rear freezer panel and gently pull it forward to expose the evaporator coil and wiring.

• Locate the defrost/evaporator thermistor: It is typically clipped to the evaporator tubing or attached with a metal clip or plastic holder.
• Check placement: Ensure the sensor is firmly attached to the coil. If it has fallen off, reattach it securely in the original position.
• Inspect wiring: Look for brittle, cracked, or ice-damaged wires. Repair any damaged sections with appropriate connectors and heat-shrink tubing.
• Test the thermistor: With the unit unplugged, disconnect the thermistor and measure resistance. Compare to expected NTC values at freezer temperature. An open or shorted reading indicates a bad sensor.
• Replace if necessary: Install a new Insignia evaporator thermistor and secure it to the coil. Route the wiring away from sharp fins and moving parts.
• Reassemble and test: Reinstall the rear panel and components, restore power, and monitor for several defrost cycles (24 hours) to confirm the E3 code clears.

Note: Persistent E3 after sensor replacement usually indicates a defective main control board.