Unit stops cooling and displays E2, fan may still run but compressor will not start.

Safety first: Disconnect power before opening the cabinet. Sharp metal edges are present around the coil.

Steps to address E2:

• 1. Reset power: Unplug the unit for 5–10 minutes, then plug back in. If E2 reappears, proceed.
• 2. Access the evaporator: Remove the front grille and filter. On Koldfront window and through-the-wall units, remove the additional screws holding the front cover to expose the evaporator coil (the cold indoor coil).
• 3. Locate the evaporator sensor: Look for a small probe clipped directly to the evaporator tubing or fins, with two thin wires leading back to the control board.
• 4. Check mounting: Ensure the sensor is firmly clipped to the coil. If it has fallen away, re-clip it in the original position so it can accurately sense coil temperature.
• 5. Inspect wiring: Follow the sensor wires to the control board. Look for cuts, pinches, or corrosion. Reseat the connector at the board.
• 6. Test with a multimeter: With the unit unplugged, disconnect the sensor and measure resistance. Compare to the room sensor if they are the same part type; they should be in a similar kΩ range at the same temperature. An open or 0 Ω reading indicates a bad sensor.
• 7. Replace sensor if needed: Install a new Koldfront-compatible evaporator thermistor and secure it to the coil.
• 8. Control board replacement: If a new sensor does not clear E2, the main control board’s sensor circuit is likely faulty and the board must be replaced.