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Central Controller Indoor Unit Recognition Failure

Likely causes

S-NET2/F1F2 communication wiring polarity mismatch — P/N reversed

Check: Compare central controller communication terminal P/N labels with actual wiring polarity → check communication error codes in controller diagnostic menu

What to do: Swap P/N wiring (correct polarity reversal) → restart controller → retry indoor unit recognition

Central controller power voltage unstable — DC 24V ±10% deviation

Check: Measure central controller power input voltage: normal DC 24V ±10% (21.6–26.4V) → check wiring resistance if voltage drops

What to do: Re-inspect and re-tighten power wiring connections → replace voltage-stabilized power supply unit → re-register indoor units after stable voltage

Registered unit count exceeds system limit — controller maximum 64 units exceeded

Check: Check number of registered indoor units on central controller → verify if exceeds 64 units → re-confirm maximum connection count in manufacturer specifications

What to do: Add additional central controller to split system → or convert some indoor units to independent remote control operation

Field tip

F1F2/S-NET2 P/N reversal is the most common installation error — always verify polarity before first startup on new installations.

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