Carrier 48/50AJ specifications General, Basic Control Usage, Series Product Line, Menu structure

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

ComfortLink™ controls.

Use this guide in conjunction with the separate installation instructions packaged with the unit. Refer to the Wiring Dia- grams literature for more detailed wiring information.

		Table 1 — A Series Product Line
UNIT		APPLICATION
48AJ		CV Unit with Gas Heat, Vertical Supply
48AK		VAV Units with Gas Heat, Vertical Supply
48AW		CV Unit with Gas Heat, Horizontal Supply
48AY		VAV Unit with Gas Heat, Horizontal Supply
48A2		CV Unit with Gas Heat, Vertical Supply with MCHX Coil
48A3		VAV Unit with Gas Heat, Vertical Supply with MCHX Coil
48A4		CV Unit with Gas Heat, Horizontal Supply with MCHX Coil
48A5		VAV Unit with Gas Heat, Horizontal Supply with MCHX Coil
50AJ		CV Unit with Optional Electric Heat, Vertical Supply
50AK		VAV Unit with Optional Electric Heat, Vertical Supply
50AW		CV Unit with Optional Electric Heat, Horizontal Supply
50AY		VAV Unit with Optional Electric Heat, Horizontal Supply
50A2		CV Unit with Optional Electric Heat, Vertical Supply with MCHX
		Coil
50A3		VAV Unit with Optional Electric Heat, Vertical Supply with MCHX
		Coil
50A4		CV Unit with Optional Electric Heat, Horizontal Supply with
		MCHX Coil
50A5		VAV Unit with Optional Electric Heat, Horizontal Supply with
		MCHX Coil
		LEGEND
CV	— Constant Volume
MCHX — Microchannel Heat Exchanger
VAV	— Variable Air Volume

The A Series units provide ventilation, cooling, and heating (when equipped) in variable air volume (VAV), variable volume and temperature (VVT®), and constant volume (CV) applica- tions. The A Series units contain the factory-installed Com- fortLink™ control system which provides full system manage- ment. The main base board (MBB) stores hundreds of unit con- figuration settings and 8 time of day schedules. The MBB also performs self diagnostic tests at unit start-up, monitors the oper- ation of the unit, and provides alarms and alert information. The system also contains other optional boards that are connected to the MBB through the Local Equipment Network (LEN). Infor- mation on system operation and status are sent to the MBB pro- cessor 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® (CCN) system using the ComfortVIEW™ software, the accessory Navigator™ hand- held display, or the System Pilot™ interface.

The ComfortLink 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 ComfortLink controls adjust the speed of the VFD based on a static pressure sensor input. In addition, the ComfortLink 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, programmed by the user, controls the unit occupied/unoccupied schedule. Up to 8 different schedules can be programmed.

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 — 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 Override 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 Configuration→ 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 ENTER 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 ESCAPE and ENTER keys simultaneously at any time 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 — The ComfortLink 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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