Indoor unit shows F1 and may run fan only with no cooling

Safety first: Turn off power to the indoor unit before accessing the control board or sensors.

Steps to try:

• Locate the room sensor: On Pioneer wall-mount units, the room sensor is usually clipped near the air intake or behind the front grille, connected by two small wires to the PCB.
• Check connection: Gently unplug and replug the sensor connector on the indoor PCB to ensure a solid connection.
• Inspect sensor: Look for damage to the sensor body or pinched wires. If the sensor is broken or corroded, it should be replaced with a Pioneer-compatible NTC sensor.
• Reset power: After reseating the connector, restore power and test operation. If F1 returns, the sensor or PCB is likely defective.

When to call a pro: If replacing the sensor does not clear F1, the indoor PCB sensor circuit may need replacement.