Display shows E3; unit may shut down cooling or run erratically, sometimes with the outdoor section not engaging properly.

Safety: Unplug the air conditioner. For window units, ensure the unit is securely supported before removing any outer covers. For portable units, place it on a stable surface.

Steps to resolve E3:

• Access condenser area: On window units, remove the outer metal shell (screws on sides/back). On portable units, remove the rear panel to expose the condenser coil.
• Locate condenser sensor: Look for a thermistor clipped to the condenser coil tubing or frame, usually near the middle or top of the coil.
• Inspect sensor and wiring: Check for broken insulation, corrosion at the connector, or a sensor that has come loose from the coil. Reseat the connector on the main PCB.
• Test sensor: With power disconnected, unplug the sensor from the board and measure resistance. Compare to expected thermistor values or to another similar sensor in the unit. Replace if open, shorted, or far out of range.
• Replace sensor if needed: Install a new Arctic King condenser temperature sensor, routing the wires along the original path and securing them with clips or zip ties away from the fan blade.
• Board diagnosis: If a new sensor does not clear E3, the main control board may not be reading the sensor correctly. Inspect for burnt components. Replacement of the main PCB is usually required and may be best done by a professional.