FieldBench
Amana codes

Amana

Comm / data pair

Lockout

ComfortBridge bus to stat or outdoor

Indoor lost the communicating thermostat or the outdoor on the data pair. Not a furnace E-code. Not 24V Y.

Walk Comm / data pair in Diagnose

Sign in for the next measurement

First check

1 Data pair, not 24 V

On Amana AVPTC 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. Data-pair polarity and splices. Never 24 VAC between the data pins.

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

The rest of the walkthrough is Diagnose.

On the plates

  • Data-pair polarity and splices. Never 24 VAC between the data pins.
  • Only one communicating master.
  • 24V fallback leftover data wires shorted to R/C.
  • A GR9T96 / AR9T96 24V furnace cannot sit on this data pair — that is a mis-pair, not a bad AVPTC board.

Plates that use Comm / data pair

Same number, other makers

Comm / data pair on Amana is not the same code on these plates.