17
Step 6 — Position and Connect Controller  — 
Wired  controllers  should  be  installed  in  a  position  that
maintains good temperature control:
• Position  the  thermostat  approximately  48  inches  above
floor level.
• Do not  position the thermostat where it  can be directly
affected by the unit’s discharge airstream.
• Avoid external walls and drafts from windows and doors.
• Avoid  positioning  near  shelves  and  curtains  as  these
restrict air movement.
• Avoid  heat  sources  such  as  direct  sunlight,  heaters,
dimmer switches, and other electrical devices.
• See  Fig.  24  for  an  example  of  communication  wire
connection.
CONTROL WIRING 
1. The  communication  wire  should  be  2-core  stranded
shielded cable.
2. For indoor unit and outdoor unit communication, use P,
Q terminals. Shielded core should be used for ground.
3. Wiring should be run according to the wiring diagram.
4. Communication wire must not form a closed loop.
Fig. 24 —Communication Wire Connection
OPTION/EXTENSIONS OF COMMUNICATION 
WIRING — To  extend  control  wiring  or  to  make  terminal
connections,  use  the  PQE  connection  wire  supplied  in  the
accessory kit and follow the steps below. 
1. Cut the connector on the outdoor unit side as shown in
Fig. 25 below.
2. Strip a suitable length of the insulation layer as shown in
Fig. 26 below. 
Fig. 26 —Stripping The Wire
3. Use a suitable screwdriver to fix the communication wire
on the outdoor unit communication terminal as shown in
Fig. 27 below.
If communication wires are used to connect indoor units, find
the corresponding port and plug it in as shown in Fig. 28.
Fig. 28 —Connecting the Communication Wires
If it is not possible to buy communication wires from Carrier,
connect the indoor unit side of communication wires using the
connector provided  with the accessories as  shown in Fig. 29
below. See Fig. 30 and 31 for typical communication wiring of
the heat pump and the heat recovery systems.
LEGEND
ACB — Auxiliary Control Board
To outdoor/indoor/MDC units
comm. bus
To wired controller comm. bus
XT2
Fig. 25 — Shearing Outdoor Connector
CAUTION
Failure to follow these  procedures  may result  in personal
injury or damage to equipment.
NEVER CONNECT the main power source to the control
or communication terminal block.
USE AN APPROPRIATE SCREWDRIVER for 
tightening the terminal screws. Do not over tighten the 
terminal screws.
IMPORTANT:  Wiring  for  communication  shall  be  two
inches  or  more  apart  from  power  source  wiring  to  avoid
electric  noise.  Do  not  insert  control/communication  and
power source wire in the same conduit.
Pay attention to polarity of the communication wire.
Fig. 27 — Connecting Communication Wire to 
Outdoor Unit Communication Terminal