FieldBench
Carrier codes

Carrier

ABCD

Lockout

Communication

Wall control or outdoor dropped off the bus.

Walk ABCD in Diagnose

5 plates — walk the one on the cabinet

First check

1 Data pair, not 24 V

On Carrier 58CVA indoor/outdoor comm is a data pair (AB, S1/S2, U, ComfortBridge, ComfortLink — whatever THIS plate uses). It is not a 24 V Y. Check polarity, continuity, and that nobody landed it on R/C. A/B/C/D, polarity, C required, no 24V on D.

Expect: Pair continuous, not shorted to chassis, polarity per the diagram.

The rest of the walkthrough is Diagnose.

On the plates

  • A/B/C/D landing, polarity, only one Infinity control, no 24V on D.
  • C present — Infinity still needs C. A 24V stat on ABCD will not drive modulation and may lock the IFC.
  • Outdoor Greenspeed / Infinity pair dropped? Check the outdoor events too.
  • C present. A 24V Performance stat on this IFC will not stage it like a 59TP6.
  • Outdoor pair on the same bus — a dead Greenspeed looks like indoor comm loss until you read events.
  • A/B/C/D, polarity, C required, no 24V on D.
  • Non-communicating 58CVX cousins may be 24V — read the actual board.

Plates that use ABCD

Same number, other makers

ABCD on Carrier is not the same code on these plates.