Unit displays E3 and may stop cooling or cycle off quickly; compressor may not start.

Safety first: Unplug the unit. The condenser area is near the hot side and compressor; avoid bending refrigerant tubing.

Steps to address E3:

• 1. Access rear section: For window units, remove the unit from the window and take off the outer shell to expose the condenser coil and compressor compartment. For portable units, remove the rear panel.
• 2. Locate condenser sensor: Find a small sensor clipped to the condenser coil or discharge line from the compressor. It will have two small wires leading back to the control board.
• 3. Inspect sensor and clip: Ensure the sensor is firmly attached to the metal surface. If loose, reattach using the original clip or a metal-safe clamp so it contacts the tubing.
• 4. Check wiring: Look for chafed or burned wires near the compressor and fan motor. Repair any damaged sections and ensure the connector at the PCB is tight.
• 5. Sensor test: With power disconnected, measure resistance and compare to the room or evaporator sensor if they share the same part number. Replace if open/shorted or if readings are wildly different.
• 6. Replace sensor: Install an Insignia-compatible condenser temperature sensor. Route wires away from hot compressor surfaces and moving fan blades.
• 7. If E3 remains: A persistent E3 with a good sensor usually indicates a defective main control board. Board replacement is a more advanced repair and may be best left to a professional.