How to Fix / Troubleshooting

Safety first: Turn OFF power at the breaker before opening the outdoor unit.

Step 1 – Locate ambient sensor: On many Gree units, the ambient sensor is mounted near the outdoor air intake grille, often hanging in free air on a small bracket.
Step 2 – Check mounting and exposure: Ensure the sensor is not touching hot surfaces and is exposed to outdoor air. Reposition if necessary.
Step 3 – Inspect wiring and connector: Follow the sensor cable to the outdoor PCB and verify the connector is secure and wires are intact.
Step 4 – Replace sensor: If the sensor body is cracked or corroded, replace it with the correct Gree ambient sensor.
Step 5 – If F4 remains: The outdoor PCB may not be reading the sensor correctly and should be tested/replaced by a technician.

Indoor unit displays F4; unit may stop heating or cooling; often related to outdoor ambient temperature sensor.

Possible Causes