Daikin Air Conditioner Error Code C1

The C1 error code on a Daikin FBQ-series air conditioner signals a transmission error between the indoor unit main PCB (A1P) and the fan PCB (A2P). These two boards must communicate continuously for the system to operate the fan correctly. When that communication is lost or corrupted, the unit shuts down and displays C1. This fault is specific to the FBQ ducted unit range.

A power reset may temporarily clear the C1 code, but if the underlying communication fault between the two PCBs still exists, the error will return once the unit attempts to operate. The root cause, whether a loose connector, damaged wiring, or a faulty board, must be physically corrected for the fault to stay resolved.

Repair costs vary depending on the root cause. If the fix is simply reseating a loose connector, you may only pay for a service call, typically in the range of $80 to $200 depending on your location. If the fan PCB or main control board needs replacement, parts and labor combined can range from $300 to $800 or more, depending on parts availability and the specific model.

Start by having a technician inspect the connector between the indoor unit PCB (A1P) and the fan PCB (A2P) to confirm it is fully and securely seated. If the connector is intact, the next steps are inspecting the wiring harness for damage and checking connector pins for corrosion. If wiring and connectors are in good condition, one or both PCBs may need to be replaced.

Continuing to operate the unit with an active C1 fault is not recommended. The error indicates the main control board cannot reliably communicate with the fan PCB, which means fan operation may be unpredictable or absent. Running the system in this state risks inadequate cooling and could contribute to further component damage.