Display shows E6, unit may not respond to remote or may not start compressor.

Safety: Disconnect power before opening any covers.

Steps:

• 1. Power cycle: Unplug the unit for 10 minutes to fully discharge internal circuits, then plug back in. If E6 reappears, continue.
• 2. Access control boards: Remove the front bezel to access the display/control board, and the rear or side panel to access the main PCB (for portables and window units). For split systems, access both indoor and outdoor control boxes.
• 3. Inspect communication cable: Locate the multi-wire harness labeled CN-COM, CN-DISP, or similar. Ensure both ends are fully seated. Look for pinched, cut, or rodent-damaged wiring.
• 4. Clean connectors: Disconnect the harness and inspect for corrosion or moisture. Clean gently with contact cleaner and reconnect firmly.
• 5. Check continuity: Use a multimeter to verify continuity on each conductor of the communication cable. Replace the harness if any conductor is open.
• 6. Board diagnosis: If wiring is intact and E6 persists, either the display PCB or main PCB is defective. Replace the less expensive/easier board first (often the display board), then the main PCB if needed.