Thermistor Designations; Status Inputs; Output Relays; High Pressure Switch - Carrier AquaSnap 30MPA Series Controls, Start-Up, Operation, Service, And Troubleshooting

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.
Table 7 — Thermistor Designations
SCROLLING
MARQUEE PIN
THERMISTOR CONNECTION
DISPLAY POINT
NAME
CLWT J8-13,14 (MBB) Cooler Leaving Fluid Temp
CEWT J8-11,12 (MBB) Cooler Entering Fluid Temp
J6-1,2 (AUX2)
D.GAS
J8-9,10 (MBB)
RGT.A
J8-6,7 (MBB),
OAT/DLWT LVT-21,22
J8-5,6 (MBB)
SPT LVT-22,23
J8-1,2 (MBB)
CDET
J8-3,4 (MBB)
CDLT
LEGEND
LWT — Leaving Water Temperature
MBB — Main Base Board
Table 8 — Status Inputs
STATUS SWITCH
Condenser Flow Switch
Dual Set Point
Remote On/Off
Cooler Flow Switch Interlock
Compressor Fault Signal, A1
Compressor Fault Signal, A2
Compressor Fault Signal, A3
Table 9 — Output Relays
RELAY
NO.
K1 Energize Compressor A1
K2 Energize Compressor A2
K3 Energize Compressor A3
K4 Energize Minimum Load Valve
K7 Liquid Line Solenoid Valve
K8 Crankcase Heater Relay
K9 Chilled Water Pump
K10 Condenser Fan/Pump
K11 Alarm Relay
THERMISTOR INPUT
Discharge Temperature
Thermistor (DTT)(Digital Com-
pressor Option Only for unit
size 020-045)
Circuit A Return Gas
Temperature (accessory, stan-
dard for unit sizes 050-071)
Outdoor-Air Temperature
Sensor (accessory) or Dual
LWT Sensor
Accessory Remote Space
Temperature Sensor, T55
Accessory
Condenser Entering Fluid
Temperature Sensor
(30MPW Only)
Condenser Leaving Fluid
Temperature Sensor
(30MPW Only)
PIN CONNECTION POINT
LVT-11,17, J7-2, J6-2 (MBB)
LVT-12,13, J7-3,4 (MBB)
LVT-14,15, J7,8 (MBB)
LVT-16,17, J6-2, J7-10 (MBB)
J9-11,12 (MBB)
J9-5,6 (MBB)
J9-8,9 (MBB)
DESCRIPTION
Table 10 — CCN Communication Bus Wiring
MANUFACTURER
Alpha
American
Belden
Columbia
Manhattan
Quabik
CURRENT SENSING BOARD (CSB) — The CSB is used
to monitor the status of each compressor by measuring current
and providing an analog input to the main base board (MBB)
or compressor expansion module (CXB).
ENABLE/OFF/REMOTE CONTACT SWITCH —
Enable/Off/Remote Control switch is a 3-position switch used
to control the unit. When switched to the Enable position, the
unit is under its own control. Move the switch to the Off posi-
tion to shut the unit down. Move the switch to the Remote Con-
trol position and a field-installed dry contact can be used to
start the unit. The contacts must be capable of handling a
24 vac, 50 mA load. In the Enable and Remote Control (dry
contacts closed) positions, the unit is allowed to operate and re-
spond to the scheduling configuration, CCN configuration and
set point data. See Fig. 7.
EMERGENCY ON/OFF SWITCH — The Emergency On/
Off switch should only be used when it is required to shut the
unit off immediately. Power to the MBB, CXB, AUX, EMM,
and scrolling marquee display is interrupted when this switch is
off and all outputs from these modules will be turned off. See
Fig. 7.
HIGH PRESSURE SWITCH (HPS) — Each unit is protect-
ed with a high pressure switch to prevent excessive condensing
pressure. See Table 11 for switch details.
Table 11 — High Pressure Switch
CARRIER PART
NUMBER
HK02ZZ001*
HK02ZZ003
* Available for 30MPA,MPW015-045, 30MPA050-071, 30MPW050-
071 high condensing option.
PRESSURE TRANSDUCERS — Each refrigerant circuit is
equipped with a suction and discharge pressure transducer. The
suction pressure transducers have a yellow body with a pres-
sure range of –6.7 to 420 psig (–46 to 2896 kPa) while the dis-
charge transducers have a red body with a pressure range of
14.5 to 667 psig (100 to 4599 kPa). These inputs connect to the
MBB (main base board) and are used to monitor the status of
the unit and to ensure the unit operates within the compressor
envelope. The transducers are used to protect the compressor
from operating at too low or too high of a pressure condition. In
some cases, the unit may not be able to run at full capacity. The
MBB will automatically reduce the capacity of a circuit as
needed to maintain specified maximum/minimum operating
pressures. Table 12
characteristics.
14
PART NO.
Regular Wiring Plenum Wiring
1895 —
A21451 A48301
8205 884421
D6451 —
M13402 M64430
6130 —
OPENS AT CLOSES AT
650 ± 10 psig 500 ± 15 psig
(4482 ± 69 kPa) (3447 ± 103 kPa)
558 ± 15 psig 435 ± 29 psig
(384 ± 103 kPa) (2999 ± 200 kPa)
summarizes pressure
The
transducer