Kelvinator split AC displays E3 and outdoor unit does not start or stops shortly after starting.

Safety: Isolate power to both indoor and outdoor units at the main breaker before touching any wiring.

Steps:

• Verify wiring diagram: Check the wiring diagram on the indoor unit cover. Kelvinator split ACs typically use terminals marked L, N, and S (signal) or numbered terminals for communication.
• Inspect terminal block: Remove the indoor unit cover over the terminal block. Ensure each wire is firmly clamped and matches the same terminal numbers/colors at the outdoor unit.
• Check for polarity: If the system uses a dedicated communication terminal, ensure the same wire goes to the same terminal on both ends (e.g., 1-1, 2-2, 3-3).
• Look for damage: Inspect the interconnecting cable between indoor and outdoor units for cuts, rodent damage, or UV deterioration.
• Tighten connections: Re-tighten all terminal screws. Loose screws can cause intermittent E3 errors.
• Power cycle: Restore power and test operation. If E3 persists, one of the PCBs may have a communication circuit failure.
• Advanced check (technician): A technician can measure DC communication voltage between signal and neutral terminals and check for correct waveform using a meter or oscilloscope.

When to call a technician: If wiring is correct and intact but E3 remains, the indoor or outdoor control PCB likely needs professional diagnosis and replacement.