System does not respond to remote; C0 appears on display or service menu

Safety: No internal electrical work is needed for basic checks.

• Replace batteries: Install fresh, high-quality batteries in the remote, ensuring correct polarity.
• Check remote output: Point the remote at a smartphone camera and press a button; you should see the IR LED flash on the screen. If not, the remote is faulty.
• Clean receiver window: Wipe the IR receiver window on the indoor unit with a soft cloth to remove dust.
• Reduce interference: Turn off or move strong light sources (e.g., direct sunlight, halogen lamps) shining directly on the receiver.
• Receiver board check: If the remote is working but the unit does not respond, the IR receiver board or indoor PCB may be defective and require replacement.