Daikin Air Conditioner Error Code C6

C6 on a Daikin FBQ series air conditioner indicates a combination error between the indoor unit PCB and the fan PCB (A2P). The indoor unit control board has determined that the communication data being sent by the fan PCB is incorrect or incompatible with its expected configuration. This fault is specific to FBQ ducted models and typically points to a PCB type mismatch or an incorrect capacity setting adaptor.

A C6 error indicates that the fan PCB communication has been flagged as incorrect, which means the indoor unit may not operate the fan motor reliably or correctly. Continuing to run the system in this condition risks inadequate airflow and potential motor stress. It is best to keep the unit off until the fault is diagnosed and resolved.

A power reset may temporarily clear the displayed fault code, but the underlying cause will remain. If the fan PCB type is incorrect or the capacity adaptor is misconfigured, the C6 error will return as soon as the unit attempts normal operation. A reset should only be used after the root cause has been identified and corrected.

Some aspects of the diagnosis, such as visually inspecting connectors and verifying adaptor settings, can be done by a knowledgeable technician. However, identifying the correct fan PCB type and safely working inside the unit requires familiarity with Daikin FBQ unit configurations. Because this fault involves internal circuit boards and capacity configuration, most homeowners should contact a qualified HVAC technician to resolve it properly.

Repair costs depend on what caused the fault. If only the capacity setting adaptor needs reconfiguring, the cost is primarily the technician's diagnostic and labor fee, typically in the range of $80 to $200. If the fan PCB needs to be replaced with the correct type, parts and labor combined can range from $250 to $600 or more depending on the model and local rates.