Error Code: FL 09 – Mismatch Between the New and Old Platforms

Modified on Thu, 22 May at 3:52 PM

Error Code: FL 09 – Mismatch Between the New and Old Platforms

What this means:
This error indicates that the indoor and outdoor units are incompatible — one is from a newer platform, and the other from an older one. The system detects the mismatch and blocks operation.

Try this first (quick check):

Confirm the model numbers of both indoor and outdoor units.
If the error appears after replacing one component, it likely means the new unit is not compatible with the older system.

Solution:

Replace either the indoor unit or outdoor unit so that both are from the same platform generation.
Ensure that both components are listed as compatible in the manufacturer’s pairing chart.

What you might need:

Replacement indoor unit
Or replacement outdoor unit (whichever is not matching the platform)

Helpful tip:
Always check compatibility during installation or part replacement. Mixing platforms (e.g., older indoor unit with newer inverter board) will result in FL 09 and system lockout.

Click here to view the detailed guide.TS40