Indoor unit stops shortly after starting, display shows E1 and unit will not run continuously.

Safety first: Switch off power at the breaker for both indoor and outdoor Tristar units before opening any covers.

Steps to try:

• Check interconnecting cable: Locate the terminal block where the indoor and outdoor units connect. Ensure all screws are tight and wires are in the correct terminals (L, N, S/COM as per wiring diagram).
• Inspect cable condition: Follow the cable run between units. Look for cuts, crushed sections, rodent damage, or signs of water ingress. Replace the cable if insulation is damaged.
• Verify polarity: On some Tristar split systems, reversed polarity on the signal wire will cause E1. Confirm that terminal numbers and colors match exactly on both ends.
• Check for corrosion: Inspect terminal blocks and connectors for rust or green corrosion. Clean lightly with contact cleaner and a soft brush, then retighten.
• Power cycle: After corrections, restore power and wait 3–5 minutes for communication to re-establish.

When to call a technician: If wiring is correct and intact but E1 persists, the indoor or outdoor control PCB communication circuit may be defective and should be tested and replaced by a professional.