Daikin

Comm

Lockout

ABCD / outdoor drop

ComfortBridge data pair only. Invalid as a diagnosis on a 24V Y1/Y2 hookup.

2 plates — walk the one on the cabinet

First check

1 Let it cool, then read the drive LED

On Daikin DC9VS overcurrent / overheat is often a dirty coil, a failed OD fan, or a locked compressor — not a dead inverter. Clear airflow, confirm the OD fan, and read the drive LED before you order a control. ABCD landing and polarity, outdoor board power, inverter comms harness.

Expect: OD fan running. Coil clean. Drive LED decoded from THIS outdoor’s card.

The rest of the walkthrough is Diagnose.

On the plates

ABCD landing and polarity, outdoor board power, inverter comms harness.
C still required at the wall control.
Indoor must be Infinity-capable. A 24ACC6-style indoor pairing is the wrong mental model.
Data pair polarity and splices. This is not 24V Y.
Indoor IFC family must be GMVC / AVPTC communicating. GR9T96 / GMEC96 / GMSS96 cannot be the ComfortBridge indoor.
One master on the bus. Outdoor board power before you condemn the indoor IFC.

Plates that use Comm

Same number, other makers

Comm on Daikin is not the same code on these plates.