11
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  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.  15  for  an  example  of  communication  wire
connection.
CONTROL WIRING
1. The  communication  wire  should  be  2-core  stranded
shielded cable.
2. For  IDU  (indoor  unit)  and  ODU  (outdoor  unit)
communication, use P, Q terminals. Shielded core should
be used for ground.
3. Wiring should be done according to wiring diagram.
4. Communication wire must not form a closed loop.
Fig. 15 —Communication Wire Connection
OPTION/EXTENSIONS OF COMMUNICATION 
WIRING — To  extend  control  wiring  or  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. 16 below.
Fig. 16 —Shearing Outdoor Connector
2. Strip a suitable length of the insulation layer as shown in
Fig. 17 below. 
Fig. 17 —Stripping the Wire
3. Use a suitable screwdriver to fix the communication wire
on the outdoor unit communication terminal as shown in
Fig. 18 below.
Fig. 18 —Connecting Communication Wire to 
Outdoor Unit Communication Terminal
If communication wires are use to  connect indoor units, find
the corresponding port and plug it directly as shown in Fig. 19.
Fig. 19 —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. 20.
See  Fig. 21 and 22  for  typical  communication  wiring  of the
heat pump and heat recovery systems.
To outdoor/indoor/MDC units
comm. bus
To wired controller comm. bus
XT2
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: Communication wiring shall be 2 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.
Connector in accessory kitConnector on indoor unit Communication cable
in field
Fig. 20 — Connecting the Communication Cable to 
Indoor Unit to Outdoor Unit Using the Supplied 
Connector