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3. Connect the red wire to (+) terminal on LVT of the plug,
the white wire to COM terminal, and the black wire to the
(–) terminal.
4. The RJ14 CCN connector on LVT can also be used, but is
only intended for temporary connection (for example, a
laptop computer running Service Tool).
Table 15 — Thermistor Designations
LEGEND
Table 16 — Status Inputs
Table 17 — Output Relays
Table 18 — CCN Communication Bus Wiring
Sensors — The electronic control uses 4 to 7 thermistors to
sense temperatures for controlling chiller operation. See
Table 15. These sensors are outlined below. Thermistors RG-
TA, RGTB, EWT, LWT, and OAT are identical in temperature
versus resistance and voltage drop performance. The dual chill-
er thermistor is 5 kat 77 F (25 C)thermistor. Space tempera-
ture thermistor is a 10 kat 77 F (25 C). The DTT thermistor
is an 86 kat 77 F (25 C)thermistor. See Thermistors section
for temperature-resistance-voltage drop characteristics.
COOLER LEAVING FLUID SENSOR — The thermistor is
installed in a well in the factory-installed leaving fluid piping
coming from the bottom of the brazed-plate heat exchanger.
COOLER ENTERING FLUID SENSOR — The thermistor is
installed in a well in the factory-installed entering fluid piping
coming from the top of the brazed-plate heat exchanger.
COMPRESSOR RETURN GAS TEMPERATURE SEN-
SOR — These thermistors are installed in a well located in the
suction line of each circuit.
OUTDOOR-AIR TEMPERATURE SENSOR (OAT) —
This sensor is factory installed on a bracket which is inserted
through the base pan of the unit.
DISCHARGE TEMPERATURE THERMISTOR
(DTT) — This sensor is only used on units with a digital
compressor. The sensor is mounted on the discharge line close
to the discharge of the digital compressor. It attaches to the dis-
charge line using a spring clip and protects the system from
high discharge gas temperature when the digital compressor is
used. This sensor is a connected to the AUX board.
REMOTE SPACE TEMPERATURE SENSOR OR DUAL
LEAVING WATER TEMPERATURE SENSOR — One of
two inputs can be connected to the LVT. See appropriate sen-
sor below.
Remote Space Temperature Sensor
— Sensor (part no.
33ZCT55SPT) is an accessory sensor that is remotely mounted
in the controlled space and used for space temperature reset.
The sensor should be installed as a wall-mounted thermostat
would be (in the conditioned space where it will not be sub-
jected to either a cooling or heating source or direct exposure
to sunlight, and 4 to 5 ft above the floor).
Space temperature sensor wires are to be connected to
terminals in the unit main control box. The space temperature
sensor includes a terminal block (SEN) and a RJ11 female
connector. The RJ11 connector is used access into the Carrier
Comfort Network
®
(CCN) at the sensor.
To connect the space temperature sensor (Fig. 10):
1. Using a 20 AWG twisted pair conductor cable rated for
the application, connect 1 wire of the twisted pair to one
SEN terminal and connect the other wire to the other
SEN terminal located under the cover of the space
temperature sensor.
2. Connect the other ends of the wires to terminals 5 and 6
on TB5 located in the unit control box.
IMPORTANT: A shorted CCN bus cable will prevent some
routines from running and may prevent the unit from start-
ing. If abnormal conditions occur, unplug the connector. If
conditions return to normal, check the CCN connector and
cable. Run new cable if necessary. A short in one section of
the bus can cause problems with all system elements on the
bus.
THERMISTOR
PIN
CONNECTION
POINT
THERMISTOR INPUT
LWT J8-13,14 (MBB) Cooler Leaving Fluid
EWT J8-11,12 (MBB) Cooler Entering Fluid
RGTA
J8-1,2 (MBB) Circuit A Return Gas
Temperature
RGTB
J8-3,4 (MBB) Circuit B (035-060 only)
Return Gas Temperature
OAT
J8-7,8 (MBB) Outdoor-Air Temperature
Sensor
SPT
J8-5,6 (MBB)
TB5-5,6
Accessory Remote Space
Temperature Sensor or
Dual LWT Sensor
DTT
J6-1,2 (AUX) Discharge Temperature
Thermistor
LWT — Leaving Water Temperature
MBB — Main Base Board
STATUS SWITCH PIN CONNECTION POINT
Chilled Water Pump 1 J7-1,2
Chilled Water Pump 2 J7-3,4
Remote On/Off LVT-13,14
Cooler Flow Switch J7-9,10
Compressor Fault Signal, A1 J9-11,12
Compressor Fault Signal, A2 J9-5,6
Compressor Fault Signal, B1 J9-8,9
Compressor Fault Signal, B2 J9-2,3
RELAY
NO.
DESCRIPTION
K1
Energize Compressor A1 (010-030)
Energize Compressor A1 and Condenser Fan Contac-
tor 3 (055,060)
K2 Energize Compressor A2 (all but 010, 015 60 Hz)
K3 Energize Chilled Water Pump 1 Output
K4 Energize Chilled Water Pump 2 Output
K5
Energize Compressor B1 (035-050)
Energize Compressor B1 and Condenser Fan Contac-
tor 3 (055,060)
K6 Energize Compressor B2 (035-060)
K7 Alarm Relay
K8 Cooler/Pump Heater
K9 Energize Condenser Fan Contactor 1 (018-060)
K10 Energize Condenser Fan Contactor 2 (018-060)
K11 Minimum Load Valve
MANUFACTURER
PART NO.
Regular Wiring Plenum Wiring
Alpha 1895 —
American A21451 A48301
Belden 8205 884421
Columbia D6451 —
Manhattan M13402 M64430
Quabik 6130 —