Daikin Air Conditioner Error Code A8

The A8 code on a Daikin FBQ series unit means the system has detected an abnormal power supply voltage at the fan motor input. The unit shuts down when voltage falls to 150V or below, or rises to 420V or above, to protect internal components. The normal acceptable supply range is 208V to 230V, plus or minus 10 percent. This is a power supply fault, not a mechanical failure of the unit itself.

No, it is not safe to continue operating the unit while an A8 fault is active. Sustained under-voltage or over-voltage conditions can overheat the fan motor windings, damage the control board, and create an electrical hazard. The unit should remain off until the supply voltage has been inspected and confirmed to be within the correct operating range.

Because this fault is directly tied to the electrical supply, both a licensed electrician and a certified Daikin HVAC technician may need to be involved. The electrician should verify and correct the incoming supply voltage and wiring, while the HVAC technician can confirm the unit's terminal block voltage and assess whether any internal components were damaged. Starting with the electrician is often the most efficient first step.

Resetting the unit by cycling power may temporarily clear the A8 code, but the error will return if the underlying voltage problem is not corrected. Running the unit with an out-of-range supply voltage risks damaging the fan motor and control board. The power supply should be confirmed to be within the 208V to 230V range before restarting the system.

Repair costs vary widely depending on the cause. If the issue is a loose wiring connection or an open phase, an electrician's service call may be all that is required, typically in the range of $100 to $300. If the wiring run needs to be replaced or the control board has been damaged by the voltage irregularity, costs can range from $300 to $800 or more depending on parts and labor in your area.