Indoor unit displays E6 and the system does not start or stops shortly after starting.

Safety first: Turn off power to both indoor and outdoor units at the breaker before touching any wiring.

• Step 1 – Verify wiring connections: Open the terminal covers on both indoor and outdoor units. Confirm that terminals (e.g., 1-2-3 or L-N-S) are wired identically at both ends and that screws are tight.
• Step 2 – Inspect cable condition: Look for cuts, crushed sections, or signs of rodent damage on the interconnecting cable. Replace the cable with the same gauge and type if damaged.
• Step 3 – Check polarity: Ensure that the communication terminal (often marked S or 3) is connected correctly between indoor and outdoor units. Reversed polarity can cause E6.
• Step 4 – Power reset: After correcting wiring, turn off the breaker for 5 minutes, then restore power and test.
• Step 5 – PCB diagnosis: If wiring is correct and E6 persists, either the indoor main PCB or outdoor main PCB communication circuit may be defective. A technician should swap-test or measure signals to identify the faulty board.