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GENERAL
This book contains
Start-Up, Controls
Operation,
Trouble-
shooting
and
Service
information
for the 48/50A
Series
rooftop
units.
See Table
1. These
units
are equipped
with
(_nfortLink
TM
controls.
Use this guide in conjunction
with the separate installation
instructions
packaged
with the unit. Refer to the Wiring Dia-
grains literature for more detailed wiring information.
Table 1 -- A Series Product Line
UNIT
48AJ
48AK
48AW
48AY
48A2
48A3
48A4
48A5
50AJ
50AK
50AW
50AY
50A2
50A3
50A4
50A5
CV
--
MCHX
--
VAV
--
APPLICATION
CV Unit with Gas Heat, Vertical Supply
VAV Units with Gas Heat, Vertical Supply
CV Unit with Gas Heat, Horizontal Supply
VAV Unit with Gas Heat, Horizontal Supply
CV Unit with Gas Heat, Vertical Supply with MCHX Coil
VAV Unit with Gas Heat, Vertical Supply with MCHX Coil
CV Unit with Gas Heat, Horizontal Supply with MCHX Coil
VAV Unit with Gas Heat, Horizontal Supply with MCHX Coil
CV Unit with Optional Electric Heat, Vertical Supply
VAV Unit with Optional
Electric Heat, Vertical Supply
CV Unit with Optional Electric
Heat, Horizontal Supply
VAV Unit with Optional
Electric Heat, Horizontal
Supply
CV Unit with Optional Electric Heat, Vertical Supply with MCHX
Coil
VAV Unit with Optional Electric Heat, Vertical Supply with MCHX
Coil
CV Unit with Optional Electric Heat, Horizontal Supply with
MCHX Coil
VAV Unit with Optional
Electric Heat, Horizontal
Supply with
MCHX Coil
LEGEND
Constant Volume
Microchannel
Heat Exchanger
Variable Air Volume
The A Series units provide ventilation,
cooling, and heating
(when equipped) in variable air volume (VAV), variable volume
and temperature
(VVT(R)), and constant volume (CV) applica-
tions.
The
A
Series
units
contain
the
factory-installed
(_mfortLink
TM
control
system
which
provides
full system
management.
The main base board (MBB) stores hundreds
of
unit configuration
settings
and 8 time of day schedules.
The
MBB also performs self diagnostic tests at unit start-up, moni-
tors the operation of the unit, and provides
alarms and alert in-
formation.
The system also contains other optional boards that
are connected
to the MBB through the Local Equipment
Net-
work (LEN). Information
on system operation
and stares are
sent to the MBB processor
by various
sensors
and optional
boards that are located at the unit. Access to the unit controls for
configuration,
set point selection, schedule creation, and service
can be done through a unit-mounted
scrolling marquee.
Access
can also be done through the Carrier Comfort Network R> (CCN)
system
using
the ComfortVIEW
rM software,
the accessory
Navigator
TM
hand-held
display, or the System Pilot
TM
interface.
The (_nfortLink
system controls all aspects of the rooftop.
It controls the supply-fan
motor, compressors,
and economiz-
ers to maintain the proper temperature
conditions.
The controls
also cycle condenser
fans to maintain
suitable head pressure.
All VAV units are equipped
with a standard VFD (variable fre-
quency
drive) for supply fan speed control and supply
duct
pressure control. The (_mfortLink
controls adjust the speed of
the VFD based on a static pressure sensor input. In addition,
the (_mfortLink
controls can raise or lower the building pres-
sure using multiple power exhaust fans controlled
from econo-
mizer damper position or from a building pressure sensor. The
control safeties are continuously
monitored
to ensure safe oper-
ation under
all conditions.
Sensors
include
suction
pressure
transducers,
discharge pressure transducers,
and saturated con-
densing temperature
sensors which allow for display of opera-
tional pressures and saturation temperatures.
A scheduling
function, prograimned
by the user, controls
the unit
occupied/unoccupied
schedule.
Up to 8 different
schedules can be progralmned.
The controls also allow the service person to operate a quick
test so that all the controlled
components
can be checked
for
proper operation.
Conventions
Used in This
Manual E The follow-
ing conventions for discussing configuration points for the lo-
cal display (scrolling marquee or Navigator accessory) will be
used in this manual.
Point names will be written with the Mode name first, then
any sub-modes,
then the point name,
each separated
by an
arrow symbol
(--->). Names
will also be shown in bold and
italics. As an example, the IAQ Economizer
Ovemde
Position
which is located in the Configuration
mode, Indoor Air Quality
Configuration
sub-mode,
and
the Air Quality
Set Points
sub-sub-mode,
would
be
written
as
(bnfiguration--€
IAQ---_IAQ.SP-_IQ.O.P.
A list of point names can be found in
Appendix
A.
This path name will show the user how to navigate through
the local display to reach the desired configuration.
The user
would
scroll through
the modes
and submodes
using
the
[]
and _--] keys. The arrow symbol in the path name repre-
sents pressing
_
to move into the next level of the
menu structure.
When a value is included
as part of the path name, it will be
shown at the end of the path name after an equals sign. If the
value represents
a configuration
setting, an explanation
will be
shown in parentheses
after the value. As an example,
Configu-
ration--+IAQ---)AQ.
CF--+IQ.AC
= 1 (IAQ Analog Input).
Pressing the _
and _
keys simultaneously
at any thne will display an expanded text description of the four-
character point name. The expanded description is shown in the
local display tables (Appendix A).
The CCN point names are also referenced in the local
display tables for users configuring the unit with CCN software
instead of the local display. The CCN tables are located in
Appendix B of this manual.
BASIC CONTROL
USAGE
ComfortLink
Controls
E The (_mfortLink
control
system is a comprehensive
unit-management
system. The con-
trol system is easy to access, configure,
diagnose
and trouble-
shoot.
The control is flexible,
providing
two types of constant
volume
cooling
control
sequences,
two variable
air volume
cooling control sequences,
and heating
control sequences
for
two-stage
electric and gas systems,
and for multiple-stage
gas
heating,
in both Occupied
and Unoccupied
schedule
modes.
This control also manages:
•
VAV duct pressure
(through
optional
VFD), with reset
•
Building
pressure
through
two different
power
exhaust
schemes
•
Condenser
fan cycling
for mild ambient
head pressure
control
•
Space ventilation
control,
in Occupied
and Unoccupied
periods,
using CO2 sensors
or external
signals,
with ven-
tilation defined by damper position
•
Smoke control functions
•
Occupancy
schedules
•
Occupancy
or start/stop
sequences
based on third party
signals
•
Alarm status and history
and run time data
•
Management
of a complete
unit service test sequence
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Table of Contents
Troubleshooting
