Furnace Control Board - Communications Connections; Terminal Screw Wire Connection; Furnace With Variable Capacity Ac Or Hp - Johnson Controls TM9V C Series Installation Manual

FIGURE 15: Furnace Control Board – Communications Connections
MODULATING FURNACE
COMMUNICATING
CONTROL
WIRE
CONNECTOR
THERMOSTAT
A +
R
TERMINAL
C
SCREW
B-
INDOOR UNIT
FIGURE 16: Terminal Screw Wire Connection
CONTROL WIRING USING COMMUNICATING
CONTROLS (VARIABLE CAPACITY OUTDOOR
MODELS)
The Communicating System consists of several intelligent communicat-
ing components including the Hx
nace and the variable capacity air conditioner or heat pump. These
components continually communicate with each other via the wire con-
nections shown in Figure 17. Commands, operating conditions, and
other data are passed continually between components over the A-R-
C-B and A-C-B bus. The result is a new level of comfort, versatility, and
simplicity.
In order to use this furnace with a variable capacity outdoor unit, it must
be installed with a communicating Hx thermostat.
Use the wiring diagram in Figure 17 to connect the furnace control
TM
and the Hx Thermostat (wall thermostat) to the communicating out-
door unit. Be sure that all of the "A+" terminals are connected together,
all of the "B-" terminals are connected together, all of the "C" terminals
are connected together and the "R" terminals from the Hx thermostat to
the indoor unit are connected together. Do NOT connect the "R" wire to
the outdoor unit. The four small screw terminals in the terminal block on
the furnace control should be used.
Johnson Controls Ducted Systems
NOTE
ENSURE ONLY ONE WIRE UNDER
TERMINAL SCREW.
TO CONNECT MORE THAN ONE WIRE:
1. CONNECT ONLY TERMINAL END OF
6" WIRE PIGTAIL.
2. USE WIRE CONNECTOR TO CONNECT
OTHER END OF PIGTAIL TO OTHER
WIRES.
OUTDOOR UNIT
TM
Thermostat, the variable speed fur-
Connect a short piece of thermostat wire (18 gage minimum) to the
ARCB terminals on the furnace control board. Use wire connectors to
connect this wire to the room thermostat wire and the outdoor unit ther-
mostat wire. The outdoor unit contains its own control transformer. DO
NOT run a thermostat "R" wire to the outdoor unit. See Figure 17 for
details.
IMPORTANT: Do not place more than one wire under any single
communication terminal screw (there are four communication termi-
nal screws). If more than one wire must be connected to a terminal
screw, attach only the terminal end of a one wire pigtail no longer than
6", and use a wire connector to connect the other end of the pigtail to
the other wires. Failure to do this will result in nuisance communica-
tion error faults. See Figure 16.
A0236-001
FIGURE 17: Furnace with Variable Capacity AC or HP
5750149-UIM-D-1219
13