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ECONOMIZER HUMIDITY CHANGEOVER SENSORS
The ComfortLink controls support 5 different changeover systems
for the economizer. These are:
•
Outdoor enthalpy switch
•
Outdoor air dry bulb
•
Differential dry bulb
•
Outdoor air enthalpy curves
•
Differential enthalpy
•
Custom curves (a combination of an enthalpy/dewpoint
curve and a dry bulb curve).
The units are equipped as standard with an outdoor air enthalpy
control. Outside air and return air dry bulb sensors which support
the dry bulb changeover method are also supplied as standard. If
the other methods are to be used, then a field-installed humidity
sensor must be installed for outdoor air enthalpy and customer
curve control and two humidity sensors must be installed for dif-
ferential enthalpy. Installation holes are pre-drilled and wire har-
nesses are installed in every unit for connection of the humidity
sensors. The ComfortLink controls have the capability to convert
the measured humidity and dry bulb temperature into enthalpy.
ACCESSORY NAVIGATOR™ DISPLAY
The accessory handheld Navigator display can be used with the
48/50P Series units. See Fig. 37. The Navigator display operates
the same way as the scrolling marquee device. The RXB and EXB
boards contain a second LEN port than can be used with the hand-
held Navigator display.
Fig. 37 — Accessory Navigator Display
CONTROL MODULE COMMUNICATIONS
Red LED
Proper operation of the control boards can be visually checked by
looking at the red status LEDs as shown on Fig. 31-34. When op-
erating correctly, the red status LEDs should blink in unison at a
rate of once every 2 seconds. If the red LEDs are not blinking in
unison, verify that correct power is being supplied to all modules.
Also, be sure that the main base board is supplied with the current
software and that all boards are configured on. If necessary, reload
current software. If the problem still persists, a board may need to
be replaced. 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 boards also have a green LED. This green LED is the indica-
tor of the operation of the LEN communications, which is used for
communications between the boards. On the MBB board the local
equipment network (LEN) LED should always be blinking when-
ever power is on. All other boards have a LEN LED that will blink
whenever power is on and there is communication occurring. If
LEN LED is not blinking, check LEN connections for potential
communication errors (J3 and J4 connectors). A 3-wire sensor bus
accomplishes communication between modules. These 3 wires
run in parallel from module to module.
Yellow LED
The MBB has one yellow LED. The Carrier Comfort Network
(CCN) LED will blink during times of network communication.
The other boards do not have a CCN communications port.
CARRIER COMFORT NETWORK
The 48/50P Series units can be connected to the CCN if desired.
See Fig. 38. The communication bus wiring is a shielded, 3-con-
ductor cable with drain wire and is field supplied and installed.
See the Installation Instructions for wiring information.
The system elements are connected to the communication 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 the COMM board. See
Fig. 21. Consult the CCN Contractor's Manual for further infor-
mation.
NOTE: Conductors and drain wire must be 20-AWG (American
Wire Gauge) minimum stranded, tinned copper. Individual
conductors must be insulated with PVC, PVC/nylon, vinyl,
Teflon
1
, 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.
When connecting to a CCN communication bus, it is important
that a color-coding scheme be used for the entire network to sim-
plify the installation. It is recommended that red be used for the
signal positive, black for the signal negative and white for the sig-
nal ground. Use a similar scheme for cables containing different
colored wires.
At each system element, the shields of its communication bus
cables must be tied together. If the communication bus is entirely
within one building, the resulting continuous shield must be con-
nected to a ground at one point only. If the communication bus
cable exits from one building and enters another, the shields
must be connected to grounds at the lightning suppressor in each
building where the cable enters or exits the building (one point
per building only). To connect the unit to the network:
1.
Turn off power to the control box.
2.
Cut the CCN wire and strip the ends of the red (+), white
(ground), and black (–) conductors. (Substitute appropriate
colors for different colored cables.)
3.
Connect the red wire to (+) terminal on the COMM board,
the white wire to COM terminal on the COMM board, and
the black wire to the (–) terminal on the COMM board.
4.
The RJ14 CCN connector on the COMM board can also
be used, but is only intended for temporary connection (for
example, a laptop computer running Service Tool).
5.
Restore power to unit.
IMPORTANT: A shorted CCN bus cable will prevent some rou-
tines from running and may prevent the unit from starting. If ab-
normal conditions occur, unplug the connector. If conditions re-
turn 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.
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INTERFACE
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Table of Contents
Troubleshooting
