How to Fix / Troubleshooting

Safety first: Turn OFF power at the breaker before removing the indoor unit cover.

Step 1 – Locate the room sensor: On most Gree wall‑mounted units, the room sensor is a small thermistor near the air intake behind the front grille, connected by thin wires to the PCB.
Step 2 – Check connections: Gently remove the front cover and locate the sensor plug on the PCB. Ensure it is firmly seated and not corroded.
Step 3 – Inspect sensor lead: Look for cuts, pinched wires, or signs of overheating. If damaged, the sensor harness should be replaced.
Step 4 – Replace sensor if needed: The sensor is usually clipped or taped near the coil or intake. Unclip it, route the new sensor in the same path, and plug it into the same PCB connector.
Step 5 – Test operation: Restore power and run the unit. If F1 persists, the indoor PCB may be defective and require replacement by a technician.

Indoor unit displays F1; unit may run but with poor temperature control or may shut down.

Possible Causes