Trane ACONT900AC43UA Service Manual page 316

Reference Materials
For instructions, components and diagrams used in
this kit, order kit #BAYACHP024A. Shown here is an
excerpt from the kit for reference:
Step 1
Be certain power to unit is DISCONNECTED.
Step 2
Remove cover panel on control box compartment.
Step 3
Disconnect and remove the existing communicating
control harness assembly. This harness consists of
the 4 wire plug assembly (J1). Disconnect/remove:
the red wire and fuse assembly from the transformer;
the blue lead from the transformer; the green/yellow
transformer ground wire; the brown wire going out to
field connections; the blue wire going out to field
connections and the double blue wire connection
terminal at the lo contractor coil.
Also disconnect and remove the two transformer
primary wires; brown/red wire coming from the LO
contactor and the black/blue wire coming from the hi
contractor. The transformer is no longer used and
should be removed.
Step 4
Connect the 24 volt harness (supplied with the kit) to
the control board, where the communicating harness
was removed (connector J1). Take the double blue
lead terminal and connect to the low voltage terminal
strip, where the previous blue lead was removed. Route
the remaining yellow, blue, orange, red, black, and
yellow/red wires out for field connection, as shown.
If the unit is a cooling only model (not a heat pump),
the orange and black leads will not be used and should
be capped off individually.
Table 1 defines maximum total length of low voltage
wiring from the outdoor unit to the indoor unit, and to
the Comfort Control.
R - C 6
Field Wiring Diagrams
Table 1
Step 5
Place the proper wiring diagram over the existing unit
wiring diagram.
Step 6
Replace the control compartment cover panel.
Step 7
Reconnect power, which was disconnected in step
#1.
Step 8
Please retain communication harness and transformer
for possible future use.