Indoor unit stops and displays E1; outdoor unit does not run.

Safety first: Turn off the main AC breaker feeding both indoor and outdoor units before opening any covers.

• Verify power and polarity: At the indoor and outdoor terminal blocks, confirm that L, N, and communication terminals (often labeled 1–2–3 or S1–S2–S3) are wired identically and firmly. Correct any reversed or loose connections.
• Inspect communication cable: Follow the multi-core cable between indoor and outdoor units. Look for cuts, crushed sections, or signs of water ingress. Tighten all terminal screws. Replace the cable if insulation is damaged or conductors are corroded.
• Check for shared circuits: Ensure the AC is on a dedicated circuit. Electrical noise from other loads can sometimes disrupt communication.
• Board diagnosis: If wiring and voltage are correct (measure rated voltage between L and N, and stable low-voltage signal on the communication line) but E1 persists, either the indoor or outdoor PCB communication circuit may be defective. This typically requires a technician with service tools to confirm.
• Do not bypass safety: Never jumper communication terminals or apply external voltage to them.