Major System Components; Main Base Board (Mbb); Screw Compressor Board (Scb); Electronic Expansion Valve (Exv) Board - Carrier ComfortLink 6 Series Controls, Start-Up, Operation, Service, And Troubleshooting

The control system cycles compressor loaders and/or com-
pressors to maintain the selected leaving fluid temperature set
point. The system automatically positions the EXV to maintain
the specified discharge gas superheat temperature in the circuit.
The system also has capabilities to control a condenser water
valve to maintain suitable discharge pressure for the 30HXC
unit. Safeties are continuously monitored to prevent the unit
from operating under unsafe conditions. A scheduling function
can be programmed by the user to control the unit's occupied
and unoccupied schedules. The control also operates a test
function and a manual control function that allows the operator
to check output signals and ensure components are operable.

MAJOR SYSTEM COMPONENTS

Main Base Board (MBB) —
majority of the control system operating software and controls
the operation of the machine. It has 11 input channels and
11 output channels.
The MBB continuously monitors input/output channel in-
formation received from all the modules and controls all output
signals for all output channels. The processor module also
controls the EXV driver module, commanding it to open or
close each EXV in order to maintain the proper cooler level.
Information is transmitted between the MBB; ComfortLink™
Compressor Protection (CCP) boards, the EXV driver module,
the Screw Compressor Board (SCB), the Energy Management
Module (EMM) and the Navigator modules through a 3-wire
communications bus called the Local Equipment Network
(LEN). The remote enhanced display is connected to the MBB
through a 3-wire communications bus, but uses a different
communication bus called the Carrier Comfort Network
(CCN). The CCN bus is also used to communicate to
other CCN devices when the unit is installed in a network
application.
Screw Compressor Board (SCB) —
8 inputs along with 2 analog and 5 discrete outputs. The SCB
module communicates the status of the inputs with the MBB
and operates the oil heater (30GXN,R only), cooler heater
(30GXN,R only) and oil pump outputs.
Electronic Expansion Valve (EXV) Board —
The EXV board has 4 inputs and 2 outputs. It receives signals
from the MBB and operates the electronic expansion devices.
The electronic expansion valve board also sends the MBB the
status of its 4 input channels.
Comfort Link Compressor Protection (CCP)
Board —
The CCP board monitors the high-pressure
switch status, running current and motor temperature for each
compressor. Each CCP board controls up to 2 compressors.
The CCP board also controls the motor cooling solenoid, oil
solenoid and contactor outputs. A pre-punched configuration
header for each compressor determines the must trip amps
setting. Each CCP board sends the MBB each compressor's
motor temperature, relay status and running current as a
percentage of the must trip amps value. The CCP board also
communicates any alarm conditions as the feedback value.
Energy Management Module (EMM) —
is available as a factory-installed option or as a field-installed
accessory. The EMM receives 4 to 20 mA inputs for the
temperature reset, cooling set point reset and demand limit
functions. The EMM also receives the switch inputs for the
field-installed 2-stage demand limit and ice done functions.
The EMM communicates the status of all inputs with the
MBB, and the MBB adjusts the control point, capacity limit,
and other functions according to the inputs received.
Enable/Off/Remote Contact Switch —
Off/Remote Contact switch is a 3-position switch used to
control the chiller (see Table 1). When switched to the Enable
This board contains the
The SCB has
The EMM
The Enable/
position the chiller is under its own control. Move the switch to
the Off position to shut the chiller down. Move the switch to
the Remote Contact position and a field-installed dry contact
can be used to start the chiller. The contacts must be capable of
handling a 24-vac, 20-mA load. In the Enable and Remote
Contact (dry contacts closed) positions, the chiller is allowed to
operate and respond to the scheduling configuration, CCN con-
figuration and set point data.
Emergency On/Off Switch —
Off switch should only be used when it is required to shut the
chiller off immediately. Power to the MBB, EMM, EXV, SCB
and Navigator display is interrupted when this switch is off and
all outputs from these modules will be turned off.
Board Addresses —
an Instance jumper that must be set to '1'. The EXV, SCB and
EMM boards have 4-position DIP switches that must be set to
'On' for all boards. The CCP address has a 4-position DIP
switch. Switches 3 and 4 set the address.

Control Module Communication

RED LED — Proper operation of the control boards can be vi-
sually checked by looking at the red status LEDs (light-
emitting diodes). When operating correctly, the red status
LEDs should be blinking in unison at a rate of once every
2 seconds. If the red LEDs are not blinking in unison, verify the
board address and that correct power is being supplied to all
modules. Be sure that the Main Base Board (MBB) is supplied
with the current software. If necessary, reload current software.
If the problem still persists, replace the MBB. A board LED
that is lit continuously or blinking at a rate of once per second
or faster indicates that the board should be replaced.
GREEN LED — The MBB has one green LED. The Local
Equipment Network (LEN) LED should always be blinking
whenever power is on. All other boards have a LEN LED that
should be blinking whenever power is on. Check LEN connec-
tions for potential communication errors at the board J3 and/or
J4 connectors. Communication between modules is accom-
plished by a 3-wire bus. These 3 wires run in parallel from
module to module. The J5 connector on the MBB provides
both power and communication directly to the Navigator.
YELLOW LED — The MBB has one yellow LED. The
Carrier Comfort Network (CCN) LED will blink during times
of network communication.
Carrier Comfort Network (CCN) Interface —
The 30GXN,R and 30HX chiller units can be connected to the
CCN if desired. The communication bus wiring is a shielded,
3-conductor cable with drain wire and is supplied and installed
in the field. The system elements are connected to the commu-
nication bus in a daisy chain arrangement. The positive pin of
each system element communication connector must be wired
to the positive pins of the system elements on either side of it.
This is also required for the negative and signal ground pins of
each system element. Wiring connections for CCN should be
made at TB3. Consult the CCN Contractor's Manual for fur-
ther information.
NOTE: Conductors and drain wire must be 20 AWG (Ameri-
can Wire Gage) minimum stranded, tinned copper. Individual
conductors must be insulated with PVC, PVC/nylon, vinyl,
Teflon, or polyethylene. An aluminum/polyester 100% foil
shield and an outer jacket of PVC, PVC/nylon, chrome vinyl,
or Teflon with a minimum operating temperature range of
–20 C to 60 C is required. Wire manufactured by Alpha (2413
or 5463), American (A22503), Belden (8772), or Columbia
(02525) meets the above mentioned requirements. It is impor-
tant when connecting to a CCN communication bus that a
color-coding scheme be used for the entire network to simplify
the installation. It is recommended that red be used for the
signal positive, black for the signal negative and white for the
signal ground. Use a similar scheme for cables containing
3
The Emergency On/
The Main Base Board (MBB) has