Left/Upper lamp blinks 0.5 seconds on, 0.5 seconds off — Indoor/outdoor unit communication error

What does Left/Upper lamp blinks 0.5-second ON, 0.5-second OFF mean?

The indoor and outdoor units are not communicating. The serial signal from the outdoor unit has not been received for 6 minutes. The indoor unit and outdoor unit may not operate.

• Miswiring between indoor and outdoor units
• Serial signal communication error
• Indoor/outdoor connecting wire issue (damage, loose connection, disconnection)

Click steps to track your progress.

1. 1

   Check the indoor/outdoor connecting wires for correct wiring, loose connections, or damage.

2. 2

   Refer to section 10-6 for specific checks on miswiring and serial signal errors.

3. 3

   If the issue persists, consider replacing the indoor/outdoor connecting wire.