Indoor unit displays F0 and cooling performance is poor or intermittent.

Safety first: Turn off power before removing covers.

• Step 1 – Locate the room sensor: The indoor ambient sensor is usually clipped near the air intake or behind the front grille. It is a small probe connected by two wires to the PCB.
• Step 2 – Check connections: Follow the sensor wires to the indoor PCB and ensure the connector is fully seated.
• Step 3 – Measure resistance: With power off, disconnect the sensor and measure its resistance with a multimeter. Compare to the Chigo service chart (typically around 5–20 kΩ depending on temperature). A reading of 0 Ω or infinite indicates a bad sensor.
• Step 4 – Replace sensor: If faulty, replace with a genuine indoor ambient temperature sensor (NTC) for your model. Route the new sensor in the same position as the original.