Indoor unit stops shortly after starting, display shows E1, outdoor unit does not run.

Safety first: Switch OFF the breaker supplying the air conditioner before opening any covers. Use a non-contact voltage tester to confirm power is off.

• Step 1 – Check power and wiring polarity: Open the indoor unit electrical cover and verify that the L (live), N (neutral), and communication terminals match the wiring diagram on the Royal Clima nameplate. Ensure the same terminal numbers and polarity are used on the outdoor unit terminal block.
• Step 2 – Inspect communication cable: Follow the multi-core cable between indoor and outdoor units. Look for cuts, crushed insulation, rodent damage, or signs of moisture ingress. Tighten all terminal screws.
• Step 3 – Measure continuity: With power OFF and cable disconnected at both ends, use a multimeter to check continuity of each conductor. Replace the cable if any conductor is open or shorted to another.
• Step 4 – Power cycle: After correcting wiring, restore power and wait 3–5 minutes. Start the unit and see if E1 clears.
• Step 5 – PCB diagnosis: If wiring is correct and E1 persists, the communication circuit on either the indoor or outdoor PCB may be defective. This requires board-level diagnosis and replacement.

When to call a technician: If you are not comfortable working with electrical wiring or if E1 remains after cable and terminal checks, contact a qualified Royal Clima technician.