Error code
C9 Room-temperature thermistor fault
Applies to 8 models
FTXF20E5V1B, FTXF25E5V1B, FTXF35E5V1B, FTXF42E5V1B, ATXF20E5V1B, ATXF25E5V1B, ATXF35E5V1B, ATXF42E5V1B
What this means
The room-temperature thermistor has failed or is outside its expected range.
When to call a technician
This fault involves refrigerant, pressure, or electrical work that must be handled by a certified technician under EU F-gas rules. Do not attempt to open the refrigerant circuit, access mains wiring, or adjust pressure components yourself. Contact a qualified installer or servicer for this one.
See the official Daikin manualA deep link to the manufacturer's own PDF for full technical detail. We link to manuals, we never host them.