Indoor unit displays F2 and may stop cooling or show abnormal defrost behavior in heat mode.

Safety first: Turn off power at the outdoor disconnect or breaker.

• Step 1 – Locate outdoor ambient sensor: It is usually mounted near the outdoor coil or on the control box, exposed to outside air.
• Step 2 – Inspect wiring: Check for damage from weather or animals. Repair or replace damaged wires.
• Step 3 – Measure sensor resistance: Disconnect the sensor from the outdoor PCB and measure resistance. Compare to the Chigo chart. Replace if readings are abnormal.
• Step 4 – Replace sensor: Install a new outdoor ambient temperature sensor, secure it in the same location, and reconnect to the PCB.