Luxaire air conditioner displays F1; indoor unit may run but temperature control is poor or erratic.

Safety: Disconnect power to the air handler before opening panels.

• Locate the sensor: On many Luxaire air handlers, the return air or coil temperature sensor is a small thermistor clipped to the evaporator coil or mounted in the return air stream.
• Check connection: Ensure the sensor plug is fully seated on the indoor control board and that wires are not pinched or broken.
• Inspect sensor: If the sensor is corroded, broken, or has come loose from the coil, replace it with the correct Luxaire thermistor part and clip it firmly back in place.
• Clear code: Restore power and cycle the thermostat. Many systems will clear F1 automatically once a valid sensor reading is detected.