Carrier 48-50PD05 User Manual

48/50PD05,06
Single Package Displacement Ventilation
or Single Zone Variable Airflow Rooftop Units
Electric Cooling/Gas Heating with PURONR (R--410A)
Refrigerant and COMFORTLinkt 1.x Controls

Controls, Start--Up, Operation, Service and

Troubleshooting Instructions

TABLE OF CONTENTS

Page

SAFETY CONSIDERATIONS 2.........................

GENERAL 3.........................................

BASIC CONTROL USAGE 3...........................

ComfortLinkt Control 3..............................

Scrolling Marquee 3..................................

Accessory Navigator Display 3..........................

Operation 3.........................................

System Pilott Device 4...............................

CCN Tables and Display 4.............................

Conventions Used in This Manual 5......................

START--UP 5.........................................

Unit Preparation 5....................................

Compressor Mounting 5...............................

Refrigerant Service Ports 5.............................

Crankcase Heater(s) 5.................................

Compressor Rotation 5................................

Power Supply 6.....................................

Internal Wiring 6.....................................

Evaporator Fan 6....................................

Condenser Fans and Motors 6...........................

Return--Air Filters 6..................................

Outdoor--Air Inlet Screens 6............................

Accessory Installation 7...............................

Orifice Change (48PD Only) 7..........................

Gas Heat (48PD Only) 7...............................

CONTROLS QUICK SET--UP 7.........................

Control Set Point and Configuration Log 7................

Standard Unit Control 7...............................

CCN Communication 8...............................

Accessories 8.......................................

Programming Operating Schedules 10....................

SERVICE TEST 10....................................

Independent Outputs 10...............................

Fan Test 10.........................................

Cooling Test 11.....................................

Heating Test 11......................................

THIRD PARTY CONTROL 11..........................

Remote Occupancy 11................................

Fire Shutdown 11....................................

Alarm Output 11.....................................

Economizer Monitoring 11.............................

Economizer Damper Control 11.........................

CONTROLS OPERATION 11...........................

Display Configuration 11..............................

Modes 12..........................................

Unit Configuration 12.................................

General Operating Sequence 13.........................

Occupancy Determination 13

Compressor Operation 14..............................

Indoor Fan Operation 14...............................

Outdoor Fan Operation 15.............................

Economizer Operation 15..............................

Indoor Air Quality (IAQ) 16............................

Cooling Modes 17...................................

Heating Modes 20....................................

Temperature Compensated Start 22.......................

Carrier Comfort Network (CCN)R Configuration 23.........

Demand Limit 23....................................

Alarm Handling 24...................................

TROUBLESHOOTING 2 4..............................

Complete Unit Stoppage 24............................

Restart Procedure 24..................................

Control Module Communication 24......................

Communication Failures 25............................

Alarms and Alerts 25.................................

Cooling Troubleshooting 30............................

Digital Scroll Controller (DSC) Troubleshooting 31..........

Economizer Troubleshooting 33.........................

Heating Troubleshooting 34............................

Variable Frequency Drive (VFD) Troubleshooting 34........

Phase Loss Protection 34..............................

Thermistor Troubleshooting 37.........................

Transducer Troubleshooting 38.........................

Forcing Inputs and Outputs 38..........................

MAJOR SYSTEM COMPONENTS 42....................

General 42.........................................

Main Base Board (MBB) 47............................

Economizer Control Board (ECB) 49.....................

Modulation Board (AUX1) 51..........................

Digital Scroll Control Board (DSC) 52....................

...........................

Variable Frequency Drive (VFD) 53......................

Integrated Gas Control (IGC) Board 54...................

Low Voltage Terminal Strip (TB1) 55.....................

Scrolling Marquee Display 56..........................

Accessory Navigatort Display 56.......................

Carrier Comfort Network (CCN)R Interface 56.............

Field--Installed Accessories 56..........................

SERVICE 59.........................................

Cleaning 60........................................

Lubrication 62......................................

Evaporator Fan Service and Replacement 62...............

Evaporator Fan Performance Adjustment 62...............

Evaporator Fan Belt Tension Adjustment 63...............

Variable Frequency Drive (VFD) Replacement 63...........

Condenser--Fan Adjustment 63..........................

Verify Sensor Performance 64..........................

48/50PD

Economizer Operation During Power Failure 64............

Evacuation 64.......................................

Refrigerant Charge 64.................................

Gas Valve Adjustment (48PD Units Only) 65...............

High Altitude (48PD Units Only) 66.....................

Main Burners (48PD Units Only) 66.....................

Filter Drier 66.......................................

Protective Devices 66.................................

Relief Devices 67....................................

Compressor Sound Shield 67...........................

Control Circuit, 24--V 67..............................

Replacement Parts 67.................................

Diagnostic LEDs 67..................................

APPENDIX A -- LOCAL DISPLAY AND

CCN TABLES 68.....................................

APPENDIX B -- STARTUP DATA 81.....................

APPENDIX C -- ADDITIONAL STARTUP DATA 91.........

APPENDIX D -- ADDITIONAL STARTUP DATA 100.......

UNIT START--UP CHECKLIST 105......................

SAFETY CONSIDERATIONS

Installation and servicing of air-conditioning equipment can be
hazardous due to system pressure and electrical components. Only
trained and qualified service personnel should install, repair, or
service air-conditioning equipment. Untrained personnel can
perform the basic maintenance functions of replacing filters.
Trained service personnel should perform all other operations.

When working on air-conditioning equipment, observe precautions
in the literature, tags and labels attached to the unit, and other
safety precautions that may apply. Follow all safety codes. Wear
safety glasses and work gloves. Use quenching cloth for unbrazing
operations. Have fire extinguishers available for all brazing
operations.

Follow all safety codes. Wear safety glasses and work gloves.
Have fire extinguisher available. Read these instructions
thoroughly and follow all warnings or cautions attached to the unit.
Consult local building codes and National Electrical Code (NEC)
for special requirements.

Recognize safety information. This is the safety--alert symbol
When you see this symbol on the unit and in instructions or
manuals, be alert to the potential for personal injury.

Understand the signal words DANGER, WARNING, and
CAUTION. These words are used with the safety--alert symbol.
DANGER identifies the most serious hazards which will result in
severe personal injury or death. WARNING signifies a hazard
which could result in personal injury or death. CAUTION is used
to identify unsafe practices which may result in minor personal
injury or product and property damage. NOTE is used to highlight
suggestions which will result in enhanced installation, reliability, or
operation.

!

WARNING

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could cause personal
injury or death.

Before performing service or maintenance operations
on unit, turn off main power switch to unit and install
lockout tag. Ensure electrical service to rooftop unit
agrees with voltage and amperage listed on the unit
rating plate.

!

CAUTION

UNIT DAMAGE HAZARD

Failure to follow this caution may cause equipment
damage.

This unit uses a microprocessor--based electronic control
system. Do not use jumpers or other tools to short out
components or to bypass or otherwise depart from
recommended procedures. Any short--to--ground of the
control board or accompanying wiring may destroy the
electronic modules or electrical components.

!

WARNING

FIRE, EXPLOSION HAZARD

Failure to follow this warning could result in personal
injury, death and/or property damage.

Improper installation, adjustment, alteration, service, or
maintenance can cause property damage, personal
injury, or loss of life. Refer to the User’s Information
Manual provided with this unit for more details.
Do not store or use gasoline or other flammable vapors
and liquids in the vicinity of this or any other appliance.

What to do if you smell gas:

1. DO NOT try to light any appliance.

2. DO NOT touch any electrical switch, or use any
phone in your building.

3.IMMEDIATELY call your gas supplier from a

neighbor’s phone. Follow the gas supplier’s
instructions.

4. If you cannot reach your gas supplier, call the fire

department.

.

2

GENERAL

This publication contains Start--Up, Controls, Operation, Service,
and Troubleshooting information for the 48/50PD rooftop units.
(See Table 1.) These units are equipped with ComfortLinkt
controls version 1.X or higher and use Puronr refrigerant. The
specific base unit installation instructions and/or wiring label
diagram may also be required in conjunction with this book as a
guide to a specific unit on the roof. All the units in Table 1 are
Displacement Ventilation or Single Zone Variable Airflow units
that provide stand--alone or network operation.

Table 1 — Rooftop Units

MODEL SIZE NOMINAL TONS

48/50PD

05 4
06

5

BASIC CONTROL USAGE

ComfortLink Control

The ComfortLink control is a comprehensive unit-management
system. The control system is easy to access, configure, diagnose
and troubleshoot.

The ComfortLink control is fully communicating and cable-ready
for connection to the Carrier Comfort Network® (CCN) building
management system. The control provides high-speed
communications for remote monitoring via the Internet. Multiple
units can be linked together (and to other ComfortLink control
equipped units) using a 3-wire communication bus.

The ComfortLink control system is easy to access through the use
of a unit-mounted display module. There is no need to bring a
separate computer to this unit for start-up. Access to control menus
is simplified by the ability to quickly select from 11 menus. A
scrolling readout provides detailed explanations of control
information. Only four, large, easy-to-use buttons are required to
maneuver through the entire controls menu. The display readout is
designed to be visible even in bright sunlight.

For added service flexibility, an accessory hand-held
Navigator™ module is also available. This portable device has an
extended communication cable that can be plugged into the unit’s
communication network at the main control box. The Navigator
display provides the same menu structure, control access and
display data as is available at the unit-mounted Scrolling Marquee
display.

S Service Test
S Temperatures
S Pressures
S Set points
S Inputs
S Outputs
S Configuration
S Timeclock
S Operating Modes
S Alarms

Through the Scrolling Marquee, the user can access all of the
inputs and outputs to check on their values and status, configure
operating parameters plus evaluate the current decision status for
operating modes. The control also includes an alarm history which
can be accessed from the display. In addition, through the Scrolling
Marquee, the user can access a built-in test routine that can be used
at start-up commissioning and to diagnose operational problems
with the unit.

Accessory Navigator Display

The accessory hand-held Navigator display can be used with the
48/50PD units. (See Fig. 2.) The Navigator display operates the
same way as the Scrolling Marquee device. The Navigator display
is plugged into the LEN (local equipment network) port on either
TB1 or the J3 port on the ECB (economizer control board).

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48/50PD

MODE

Run Status

Service Test

Temperature

Pressures

Setpoints

Inputs

Outputs

Configuration

Time Clock

Operating Modes

Alarms

Alarm Status

ESCAPE

ENTER

C06320

Fig. 1 -- Scrolling Marquee

Scrolling Marquee

This device is the keypad interface used to access the control
information, read sensor values, and test the unit. The Scrolling
Marquee is located in the main control box and is standard on all
units. The Scrolling Marquee display is a 4-key, 4-character,
16-segment LED (light-emitting diode) display module. The
display also contains an Alarm Status LED. (See Fig. 1.)

The display is easy to operate using 4 buttons and a group of 11
LEDs that indicate the following menu structures:

S Run Status

C06321

Fig. 2 -- Accessory Navigator Display

Operation

All units are shipped from the factory with the Scrolling Marquee
display, which is located in the main control box. (See Fig. 1.) In
addition, the ComfortLink control also supports the use of the
handheld Navigator display.

Both displays provide the user with an interface to the
ComfortLink control system. The displays have up and down
arrow keys, an ESCAPE key and an ENTER key. These keys are
used to navigate through the different levels of the display
structure. The Navigator display and the Scrolling Marquee operate
in the same manner, except that the Navigator display has multiple
lines of display and the Scrolling Marquee has a single line. All
further discussions and examples in this document will be based on
the Scrolling Marquee display. See Table 2 for the menu structure.

The four keys are used to navigate through the display
structure, which is organized in a tiered mode structure. If the
buttons have not been used for a period, the display will default to
the AUTO VIEW display category as shown under the RUN
STATUS category. To show the top-level display, press the
ESCAPE key until a blank display is shown. Then use the up and

3

down arrow keys to scroll through the top-level categories. These
are listed in Appendix A and will be indicated on the Scrolling
Marquee by the LED next to each mode listed on the face of the
display.

When a specific mode or sub-mode is located, push the ENTER
key to enter the mode. Depending on the mode, there may be
additional tiers. Continue to use the up and down keys and the
ENTER keys until the desired display item is found. At any time,
the user can move back a mode level by pressing the ESCAPE key.
Once an item has been selected the display will flash showing the
item, followed by the item value and then followed by the item
units (if any).

Items in the Configuration and Service Test modes are password
protected. The display will flash PASS and WORD when required.
Use the ENTER and arrow keys to enter the four digits of the
password. The default password is 1111.

Pressing the ESCAPE and ENTER keys simultaneously will scroll
an expanded text description across the display indicating the full
meaning of each display point. Pressing the ESCAPE and ENTER
keys when the display is blank (MODE LED level) will return the
display to its default menu of rotating AUTO VIEW display items.

48/50PD

In addition, the password will need to be entered again before
changes can be made.

Changing item values or testing outputs is accomplished in the
same manner. Locate and display the desired item. If the display is
in rotating auto-view, press the ENTER key to stop the display at
the desired item. Press the ENTER key again so that the item value
flashes. Use the arrow keys to change the value of state of an item
and press the ENTER key to accept it. Press the ESCAPE key and
the item, value or units display will resume. Repeat the process as
required for other items.

There are some points that can be forced from the Scrolling
Marquee or the Navigator. If the user needs to force a variable,
follow the same process as when editing a configuration parameter.
A forced variable, regardless where the force has come from will
be displayed with a blinking “.” on a Scrolling Marquee and a
blinking “f” on a Navigator following its value. For example, if

economizer commanded position (EC.CP) is forced, the Navigator
display shows “80f”, where the “f” is blinking to signify a force on
the point. The Scrolling Marquee display shows “80.” Where the
“.” is blinking to signify a force on the point. Remove the force by
selecting the point that is forced with the key ENTER and then
pressing the up and down arrow keys simultaneously.

Depending on the unit model, factory-installed options and
field-installed accessories, some of the items in the various Mode
categories may not apply.

System Pilott and Touch Pilot Devices

The System Pilot device (33PILOT--01) and Touch Pilot device
(33CNTPILOT) can be used as CCN communication
user--interfaces. These devices can be put on the CCN bus and
addressed to communicate with any other device on the network.
Unlike the Scrolling Marquee and Navigator, these pilots read the
48/50PD’s CCN tables and the units CCN points can be monitored,
forced, or configured.

IMPORTANT: Multiple zoning application is NOT
recommended at this time with the PD products.

Additionally, the System Pilot device can serve as a wall--mounted
temperature sensor for space temperature measurement. The
occupant can use the System Pilot device to change set points. A
security feature is provided to limit access of features for
unauthorized users. See Fig. 3 for System Pilot device details.

CCN Tables and Display

In addition to the unit--mounted Scrolling Marquee display, the
user can also access the same information through the CCN tables
by using the Service tool or other CCN programs/devices. The
variable names used for the CCN tables and the Scrolling Marquee
menus may be different and more items may be displayed in the
CCN tables. Details on the CCN tables are included with the local
display menus in Appendix A. Appendix A is structured towards
the organization of the local display (Scrolling Marquee) menus.
Because of the variety of CCN programs and devices, the CCN
tables, sub-- tables, and points are referenced within that
organization.

RUN

STATUS

Auto View

of

Run Status

(VIEW)

↓

Software

Version

Numbers

(VERS)

↓

Control

Modes

(MODE)

↓

Cooling

Status

(COOL)

↓

Heating

Status

(HEAT)

↓

Economizer

Status

(ECON)

↓

Component

Run Hours

(HRS)

↓

Component

Starts

(STRT)

SERVICE

TEST

Service Test

Mode

(TEST)

↓

Test Independent

Outputs

(INDP)

↓

Tes t Fa n s

(FANS)

↓

Test Cooling

(COOL)

↓

Test Heating

(HEAT)

Table 2 — Scrolling Marquee Mode and Menu Display Structure

TEMPERATURES PRESSURES SETPOINTS INPUTS OUTPUTS CONFIGURATION

Air

Temperatures

(AIR.T)

↓

Refrigerant

Temperatures

(REF.T)

General

Inputs

(GEN.I)

↓

Current

Sensor Inputs

(CS.IN)

↓

Air Quality

Inputs

(AIR.Q)

Fan
Outputs
(FANS)

↓

Cool
Outputs
(COOL)

↓

Heat
Outputs
(HEAT)

↓

Economize

r
Outputs
(ECON)

↓

Alarm

Relay

(ALRM)

Display

Configuration

(DISP)

↓

Unit

Configuration

(UNIT)

↓

Cooling

Configuration

(COOL)

↓

Heating

Configuration

(HEAT)

↓

Economizer

Configuration

(ECON)

↓

Air Quality

Cfg.

(AIR.Q)

↓

Alarm Relay

Config.

(ALM.O)

↓

PID

Configuration

(PID)

↓

Sensor

Calibration

(TRIM)

↓

CCN

Configuration

(CCN)

TIME

CLOCK

Tim e o f Da y

(TIME)

↓

Month, Date

Day an d

Year

(DATE)

↓

Daylight

Savings

Tim e

(DST)

↓

Local Time

Schedule
(SCH.L)

↓

Local

Holiday

Schedules

(HOL.L)

OPERATIN

G

MODES

Control

Modes

(MODE)

↓

Cool Mode

Diagnostic

(COOL)

↓

Heat Mode

Diagnostic

(HEAT)

↓

Economizer

Diagnostic

(ECON)

↓

Demand

Listing

(DMD.L)

ALARMS

Reset All

Current
Alarms

(R.CURR)

↓

Reset

Alarm

History

(R.HIST)

↓

Currently

Active

Alarms

(CURR)

↓

Alarm

HIstory

(HIST)

4

NAVIGATE/

/

EXIT

SCROLL

Fig. 3 -- System Pilott User Interface

+

-

PAGE

MODIFY
SELECT

C06322

Force Hierarchy

There is a hierarchy in CCN with regards to forcing a point.
Programs and devices write a force at different priority levels. A
higher level (smaller number, 1 being the highest) will override a
lower level force. The Scrolling Marquee uses a Control Force at
level 7. The Navigator writes a Service Force which is level 3.
System Pilots and Touch Pilots write Supervisor Forces at level 4.
Network programs can be set to write different level priority forces.

Generic Status Display Table

The GENERIC points table allows the service/installer the ability
to create a custom table in which up to 20 points from the 5 CCN
categories (Points, Config, Service--Config, Set Point, and
Maintenance) may be collected and displayed.

In the Service-- Config table section, there is a table named
“GENERICS.” This table contains placeholders for up to 20 CCN
point names and allows the user to decide which points are
displayed in the GENERIC points sub--table under the status
display table. Each one of these placeholders allows the input of an
8--character ASCII string. Using a CCN interface, enter the Edit
mode for the Service--Config table “GENERICS” and enter the
CCN name for each point to be displayed in the custom points
table in the order they will be displayed. When done entering point
names, download the table to the rooftop unit control.

IMPORTANT: The computer system software (ComfortVIEWt,
Service Tool, etc.) that is used to interact with CCN controls,
always saves a template of items it considers as static (e.g., limits,
units, forcibility, 24--character text strings, and point names) after
the software uploads the tables from a control. Thereafter, the
software is only concerned with run time data like value and
hardware/force status. With this in mind, it is important that any
time a change is made to the Service--Config table “GENERICS”
(which in turn changes the points contained in the GENERIC point
table), that a complete new upload be performed. This requires that
any previous table database be completely removed first. Failure to
do this will not allow the user to display the new points that have
been created and the CCN interface will have a different table
database than the unit control.

Conventions Used in This Manual

The following conventions for discussing configuration points for
the local display (Scrolling Marquee or Navigator™ accessory) will
be used in this manual.

Point names will be written with the Mode name first, then any
submodes, then the point name, each separated by an arrow symbol
(→). Names will also be shown in bold and italics. As an example,
the Fan Status Switch which is located in the Configuration mode,
and Unit sub-mode would be written as Configuration→

UNIT→FN.SW.

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 sub-modes using the up and down
keys. The arrow symbol in the path name represents 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
parenthesis after the value. As an example,
Configuration→UNIT→FN.SW = 1 (Normal Open).

Pressing the ESCAPE and ENTER keys simultaneously will scroll
an expanded text description of the point name across the display.
The expanded description is shown in the local display tables but
will not be shown with the path names in text.

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. See Appendix A of this manual.

START-UP

IMPORTANT: Do not attempt to start unit, even momentarily,

until all items on the Start--Up Checklist (last page) and the
following steps have been completed.

Unit Preparation

Check that unit has been installed in accordance with these
installation instructions and all applicable codes.

Compressor Mounting

Compressors are internally spring mounted. Do not loosen or
remove compressor holddown bolts.

Refrigerant Service Ports

Each independent refrigerant system has a total of 3 Schrader-type
service gauge ports per circuit. One port is located on the suction
line, one on the compressor discharge line, and one on the liquid
line. Be sure that caps on the ports are tight.

Crankcase Heater(s)

Compressor crankcase heater operation varies depending on the
unit size and type. In general for all units, the crankcase heaters are
energized if there is power to the unit, the compressor is not
operating, and the ambient temperature is below 75_F.

IMPORTANT: Unit power must be on for 24 hours prior to
start--up. Otherwise, damage to compressor may result.

Compressor Rotation

!

CAUTION

UNIT DAMAGE HAZARD

Failure to follow this caution may result in unit damage.

Improper wiring will cause compressor stoppage and alarm.
Correct wiring by switching leads as indicated below.

48/50PD

5

CONTROL BOX

AND

COMPRESSOR

ELECTRICAL

OPTIONS PANEL

OUTDOOR AIR

SCREEN

(HIDDEN)

48/50PD

INDOOR MOTOR

ACCESS DOOR

GAS SECTION
ACCESS

CONDENSER COIL
ACCESS PANEL

BASEPAN CONNECTIONS

ACCESS PANEL

Fig. 4 -- Panel and Filter Locations

On 3-phase units, it is important to be certain the compressors are
rotating in the proper direction. To determine whether or not
compressors are rotating in the proper direction, use a
phase-rotation meter on the unit input power to check for
L1-L2-L3 or clockwise rotation or use the Service Test mode to
energize a compressor. If the compressor is rotating in the wrong
direction, the controls will stop the compressor and display alarm
for “Circuit A Failure to Pressurize.”

IMPORTANT: Indoor or outdoor fan rotation direction may not
indicate proper input power phase sequence, as some 3-phase units
use single-phase fan motors.

To correct the wrong compressor rotation direction, perform the
following procedure:

1. Turn off power to the unit and lock out the power.

2. Switch any two of the incoming unit power leads.

3. Turn on power to the unit.

4. Verify corrected compressor rotation.

Power Supply

All 208/230-v units are factory wired for 230-v power supply. If
the 208/230-v unit is to be connected to a 208-v power supply, the
transformers (TRAN1 and TRAN2) must be rewired by moving
the wire from the 230-volt connection and moving to the 200-volt
terminal on the primary side of the transformer. Refer to unit label
diagram for additional information.

Internal Wiring

Check all electrical connections in unit control boxes; tighten as
required.

Evaporator Fan

Fan belt and variable pulleys are factory-- installed, but may need to
be adjusted for specific applications. Be sure that the fans rotate in
the proper direction. See Appendix C for unit specific fan
performance data. See Appendix D for unit specific air quality

FILTER ACCESS DOOR

C07002

limits, evaporator fan motor specifications, FIOP static pressures,
and fan RPM for various motor pulley settings. Appendix C and D
are based on 100% fan speed (VFD at 60Hz). To alter fan
performance, see Evaporator Fan Performance Adjustment in the
Service section.

The Supply Fan Minimum Speed
(Configuration→UNIT→FS.MN) and the Supply Fan Maximum
Speed (Configuration→UNIT→FS.MX) can also be used to alter
fan performance. The fan should run at the maximum fan speed
when setting up the application design point. The unit is equipped
with a Variable Frequency Drive (VFD). The VFD’s settings
should not be used for adjusting fan performance. Specific VFD
information can be found in Appendix B.

IMPORTANT: When setting up and starting the unit, the heating
minimum CFM requirements must be upheld when changing belts,
pulleys, and configurations. During heating mode, the fan speed is
always set to Supply Fan Maximum Speed (FS.MX).

Condenser Fans and Motors

Condenser fans and motors are factory set. Refer to Condenser-Fan
Adjustment section as required.

Return--Air Filters

Check that correct filters are installed in filter tracks (see Physical
Data table in Installation Instructions). Do not operate unit without
return-air filters.

IMPORTANT: For units with 4-in. filter option, units are shipped
with standard 2-in. filters. To install 4-in. filters, the filter spacers
must be removed.

Outdoor--Air Inlet Screens

Outdoor-air inlet screens must be in place before operating unit.

6

Accessory Installation

Check to make sure that all accessories including sensors have
been installed and wired as required by the instructions and unit
wiring diagrams.

Orifice Change (48PD Only)

This unit is factory assembled for heating operation using natural
gas at an elevation from sea level to 2000 ft.

Use accessory high altitude kit when installing this unit at an
elevation of 2000 to 7000 ft. For elevations above 7000 ft, refer to
High Altitude section to identify the correct orifice size for the
elevation. Purchase these orifices from your local Carrier dealer.
Follow instructions in accessory Installation Instructions to install
the correct orifices.

Use accessory LP (liquid propane) gas conversion kit when
converting this unit for use with LP fuel usage for elevations up
to 7000 ft. For elevations above 7000 ft, refer to High Altitude
section to identify the correct orifice size for the elevation.
Purchase these orifices from your local Carrier dealer. Follow
instructions in accessory Installation Instructions to install the
correct orifices.

Gas Heat (48PD Only)

Verify gas pressures before turning on heat as follows:

1. Turn off field-supplied manual gas stop, located external to
unit.

2. Connect pressure gauge to supply gas tap, located on
field-supplied manual shutoff valve. (See F ig. 5.)

3. Connect pressure gauge to manifold pressure tap.

4. Turn on field-supplied manual gas stop. Enter Service Test
mode by setting Service Test→TEST to “ON” using the
Scrolling Marquee display. Use the Service Test feature to
set Service Test→HEAT→HT.1 to ON (first stage of heat)
using the Scrolling Marquee.

C06323

Fig. 5 -- Field Gas Piping

5. After the unit has run for several minutes, verify the supply
gas pressure is between 5.5--in. wg to 13.0-- in. wg, and the
manifold pressure is 3.50--in. wg on sizes 03-- 14 and 3.00
on size 16. If manifold pressure must be adjusted, refer to
Gas Valve Adjustment section.

IMPORTANT: Supply gas pressure must not exceed 13.0--in. wg.

6. Set Service Test→HEAT→HT.1 to OFF using Scrolling
Marquee.

7. Exit Service Test mode by setting Service Test→TEST to
“OFF” using the Scrolling Marquee.

CONTROLS QUICK SET--UP

The following information will provide a quick guide to setting up
and configuring the 48/50PD series units with ComfortLink™
controls. Unit controls are pre-configured at the factory for
factory-installed options. Field-installed accessories will require
configuration at start-up. Service Test is recommended for initial
start--up. Additionally, specific job requirements may require
changes to default configuration values. See the CCN and Display
parameter tables and other sections of these instructions for more
details.

Control Set Point and Configuration Log

During start up, accessory installation, and equipment service set
points and/or configuration changes might have to be made. When
setting set points or changing configuration settings,
documentation is recommended. The Control Log starting on page
106 should be filled out and left with the unit at all times. A copy
should also be provided to the equipment owner.

Standard Unit Control

There are two different applications these units can be applied to,
Displacement Ventilation and Single Zone VAV. F o r ei th er
application a direct wired space sensor can be used or a
communicating sensor/thermostat can be used. Installation of an
accessory supply air temperature (SAT) sensor in the supply duct is
recommended when using a communication type control. A supply
duct SAT measurement is valid for heating mode display, while the
factory--standard internal SAT is not valid for heating due to its
location upstream of the heating section. When installing the
supply duct SAT, the heating mode display is enabled by setting
Configuration→HEAT→SAT→SAT.H to ENBL.

There are several configurations that should be considered for
Displacement Ventilation or Single Zone VAV applications. Table
3 shows these configuration defaults and specific application
settings. These settings typical values and should be adjusted for
each actual specific unit application. Refer to the Operation section
for more detail on these configurations and how they effect the
units operation.

IMPORTANT: Multiple zoning application is not recommended
at this time with the PD product.

Space Temperature Sensor Control—Direct Wired
(T--55, T--56, or

Wire accessory space temperature sensor(s) to the T--55 terminals
on the field connection terminal board located at the unit control
box. No configuration is required when installing a T--55, T--56, or
T--59. Refer to Field-Installed Accessories section for additional
information.

T--58 Communicating Thermostat

Install the T -- 58 communicating thermostat. Connect the CCN
communication bus from the T--58 to the CCN terminals on the
field connection terminal board located at the unit control box.
Configure the unit’s CCN communication element number, bus
number, and baud rate. Configure the T --58’s CCN communication
bus number and baud rate the same as the unit, while the element
number has to be different. Configure the T--58 to send SPT to the
unit’s element number. Refer to the Field--Installed Accessories
section for additional information.

T--59)

48/50PD

7

Table 3 — Application Specific Configurations

ITEM EXPANSION DEFAULT UNITS

SASP Cool Supply Air Setpoint 65 dF 65 55

FS.MX Supply Fan Maximum Speed 100 % 100 100

FS.MN Supply Fan Maximum Speed 20 % 20 70

FS.VM Vent Mode Fan Speed 50 ∧F 50 50

MIN.C Min Compressor Capacity 70 % 15 70

FS.CD Fan Speed Control Demand 3 ∧F 3 3

SA.MU SASP Maximum Reset Up 10 ∧F 3 5

SA.MD SASP Maximum Reset Down --- 1 0 ∧F --- 3 --- 5

MP.MX Econ Min at Max Fanspeed 30 % 30 30

PE1.C Power Exhaust Stage 1 CFM 600 cfm 600 600

IDF.C Indoor Fan Max Speed CFM

System Pilot -- Communication Space Sensor

Install the System Pilot and connect the CCN communication bus
from it to the units CCN connection on the low voltage terminal

48/50PD

board. Configure the unit’s CCN communication element number,
bus number, and baud rate. Refer to the System Pilot’s installation
instructions for configuring it to be used as a space temperature and
attaching it to a unit.

Gen III TEMP Monitor -- Linkage Communication
Thermostat

Install the linkage thermostat. Connect the CCN communication
bus from the Stat to the CCN terminals on the field connection
terminal board located at the unit control box. Configure the unit’s
CCN communication element number, bus number, and baud rate.
Refer to the Linkage Thermostat’s installation instructions for
configuring the Stat and additional information about it.

(33CSTMT--01)

Space Humidistat Control

The humidistat input is provided on the field connection terminal
board. The Space Humidity Switch configuration,
Configuration→UNIT→RH.SW, identifies the normally open or
normally closed status of this input at LOW humidity. Humidistat
1 terminal is the 24 VAC source for dry contact and the Humidistat
2 terminal is the signal input.

Relative Humidity Sensor Control

For units with the economizer option (with the ECB--economizer
control board), the humidity sensor input is provided on the field
connection terminal board. The sensor can be used in addition to
or instead of a humidistat. The RH Sensor on OAQ Input
configuration, Configuration→UNIT→RH.S=YES, identifies that
the sensor is being used instead of an OAQ sensor. Terminal 1 is
the 24vdc loop power and Terminal 4 is the 4 --20 mA signal input.
Refer to the Field Installed Accessories for more information.

CCN Communication

Configure Configuration→CCN→CCN.A to desired element
number (Default is 1). Configure Configuration→CCN→ CCN.B
to desired bus number (Default is 0). Configure
Configuration→CCN→BAUD to desired code number for baud
rate (Default is 3 = 9600 baud).

Accessories

Below are quick configuration settings for field installed
accessories. If these accessories were installed by the factory, they
will already be configured. See the Field-- Installed Accessories
section, third party control, control connection tables, and CCN or
Display parameter tables for any accessories not mentioned below
and any additional information on accessories.

Economizer

If an Economizer accessory was field installed, the unit must be
configured for it by setting Configuration→ECON→EC.EN to
YES. The default settings for the other economizer configurations

1600 (05)
2000 (06)

cfm

should be satisfactory. If they need to be changed, additional
information about these configuration settings can be found in the
Economizer section.

Power Exhaust

If a Power Exhaust accessory was field installed, the unit must be
configured for it by setting Configuration→ECON→PE.EN to
ENBL. The default settings for the other power exhaust
configurations should be satisfactory. If they need to be changed,
additional information about these configurations can be found in
the Power Exhaust section.

Electric Heat

If an Electric Heat accessory was field installed, the unit must be
configured for it by setting Configuration→HEAT→HT.TY to a
value of 2. The number of electric heat stages must be configured
by setting Configuration→HEAT→N.HTR per the installed
heater.

Fire Shutdown

If a Fire Shutdown or Smoke Detector accessory was field
installed, the unit must be configured for it by setting
Configuration→UNIT→FS.SW to normally open (1) or normally
closed (2) when there is not a fire alarm. Normally open (1) is the
preferred configuration.

IMPORTANT: On standard units, the fire shutdown input is the
terminals Fire Shutdown 1 and 2.

Outdoor Enthalpy

If an Outdoor Enthalpy accessory was field installed, the unit must
be configured for it by setting Configuration→ECON→EN.SW,
identifies the normally open or normally closed status of this input
when the outdoor enthalpy is low.

IAQ Switch

If an IAQ Switch accessory was field installed, the unit must be
configured for it by setting Configuration→AIR.Q→II.CF,
identifies the normally open or normally closed status of this input
when the indoor air quality value is low (good) and also selects the
unit response to this input.

IMPORTANT: An IAQ switch cannot be used if an enthalpy
switch is already on this input.

IAQ Sensor

If an CO2Sensor accessory was field installed, the unit must be
configured for it by setting Configuration→AIR.Q→IA.CF
selects the unit response to this input. Default conversion to 0 to
2000 ppm.

OAQ Sensor

If an Outdoor Air Quality Sensor accessory was field installed, the
unit must be configured for it by setting Configuration→AIR.Q
→OA.CF selects the unit response to this input. Default
conversion to 0 to 2000 ppm.

DISPLACEMENT

VENTILATION

1600 (05)
2000 (06)

SINGLE ZONE

VAV

1600 (05)
2000 (06)

8

Fan Status

If a Fan Status accessory was field installed, the unit must be
configured for it by setting Configuration→UNIT→FN.SW to
normally open (1) or normally closed (2). Normally open (1) is the
preferred configuration.

IMPORTANT: Fan Status input is not on the terminals marked
Fan Status.

Table 4 — Setting an Occupied Time Schedule - Weekdays Only for 7:30 to 22:30

Filter Status

If a Filter Status accessory was field installed, the unit must be
configured for it by setting Configuration→UNIT→FL.SW to
normally open (1) or normally closed (2). Normally open (1) is the
preferred configuration.

DISPLAY

MENU

TIMECLOCK

SCH.L

SUB SUB

MODE

PER.1

KEYPAD

ENTRY

ENTER

ENTER

ENTER

ENTER

Y

ENTER

Y

ENTER

ESCAPE

B

ENTER

ENTER

Y

ENTER

Y

ENTER

ESCAPE

B

ENTER

Y

ENTER

ESCAPE

B

ENTER

Y

ENTER

ESCAPE

B

ENTER

Y

ENTER

ESCAPE

B

ENTER

Y

ENTER

ESCAPE

B

ENTER

Y

ENTER

ESCAPE

ESCAPE

ESCAPE

ITEM DISPLAY ITEM EXPANSION COMMENT

Local Occupancy Schedule

OCC.1 Period Occupied Time

00.00

00.00

07.00

07.00

07.30

07.30

OCC.1 07.30 Period Occupied Time

UNC.1 00.00 Period Unoccupied Time

00.00

00.00

22.00

22.00

22.30

22.30

UNC.1 22.30 Period Unoccupied Time

MON.1 NO Monday In Period

NO

YES

YES

MON.1 YES Monday In Period

TUE.1 NO Tuesday In Period

NO

YES

YES

TUE.1 YES Tuesday In Period

WED.1 NO Wednesday In Period

NO

YES

YES

WED.1 YES Wednesday In Period

THU.1 NO Thursday In Period

NO

YES

YES

THU.1 YES Thursday In Period

FRI.1 NO Frida y In Perio d

NO

YES

YES

FRI.1 YES Friday In Period

Scrolling stops

Hours Flash

Select 7

Change accepted, minutes flash

Select 30

Change accepted

Item/Value/Units scrolls again

Scrolling stops

Hours Flash

Select 22

Change accepted, minutes flash

Select 30

Change accepted

Item/Value/Units scrolls again

Scrolling stops

Select YES

Change accepted

Item/Value/Units scrolls again

Scrolling stops

Select YES

Change accepted

Item/Value/Units scrolls again

Scrolling stops

Select YES

Change accepted

Item/Value/Units scrolls again

Scrolling stops

Select YES

Change accepted

Item/Value/Units scrolls again

Scrolling stops

Select YES

Change accepted

Item/Value/Units scrolls again

48/50PD

9

Programming Operating Schedules

The ComfortLinkt controls will accommodate up to eight
different schedules (Periods 1 through 8), and each schedule is
assigned to the desired days of the week. Each schedule includes
an occupied on and off time. As an example, to set an occupied
schedule for 8 AM to 5 PM for Monday through Friday, the user
would set days Monday through Friday to ON for Period 1. Then
the user would configure the Period 1 Occupied From point to
08:00 and the Period 1 Occupied To point to 17:00. To create a
different weekend schedule, the user would use Period 2 and set
days Saturday and Sunday to ON with the desired Occupied On
and Off times.

IMPORTANT: By default, the time schedule periods are
programmed for 24 hours of occupied operation.

To create a schedule, perform the following procedure:

1. Scroll to the Configuration mode, and select CCN
CONFIGURATION (CCN). Scroll down to the Schedule
Number (Configuration→CCN→SCH.O=SCH.N). If
password protection has been enabled, the user will be
prompted to enter the password before any new data is

48/50PD

accepted. SCH.N has a range of 0 to 99. The default value
is 1. A value of 0 is always occupied, and the unit will
control to its occupied set points. A value of 1 means the
unit will follow a local schedule, and a value of 65 to 99
means it will follow a CCN schedule. Schedules 2-- 64 are
not used as the control only supports one internal/local
schedule. If one of the 2--64 schedules is configured, then
the control will force the number back to 1. Make sure the
value is set to 1 to use a local schedule.

2. Enter the Time Clock mode. Scroll down to the LOCAL
TIME SCHEDULE (SCH.L) sub--mode, and press
ENTER. Period 1 (PER.1) will be displayed.

3. Scroll down to the MON.1 point. This point indicates if
schedule 1 applies to Monday. Use the ENTER command
to go into Edit mode, and use the Up or Down key to
change the display to YES or NO. Scroll down through the
rest of the days and apply schedule 1 where desired. The
schedule can also be applied to a holiday.

4. Configure the beginning of the occupied time period for
Period 1 (OCC). Press ENTER to go into Edit mode, and
the first two digits of the 00.00 will start flashing. Use the
Up or Down key to display the correct value for hours, in
24--hour (military) time. Press ENTER and hour value is
saved and the minutes digits will start flashing. Use the
same procedure to display and save the desired minutes
value.

5. Configure the unoccupied time for period 1 (UNC). Press
ENTER to go into Edit mode, and the first two digits of the

00.00 will start flashing. Use the Up or Down key to display
the correct value for hours, in 24--hour (military) time. Press
ENTER and hour value is saved and the minutes digits will
start flashing. Use the same procedure to display and save
the desired minutes value.

6. The first schedule is now complete. If a second schedule is
needed, such as for weekends or holidays, scroll down and
repeat the entire procedure for period 2 (PER.2). If
additional schedules are needed, repeat the process for as
many as are needed. Eight schedules are provided. See
Table 4 for an example of setting the schedule.

The Service Test function can be used to verify proper operation of
compressors, heating stages, indoor fan, outdoor fans, power
exhaust fans, economizer, crankcase heaters, and the alarm relay.
Use of Service Test is recommended at initial system start up and
during troubleshooting (See Table 5 for point details).

Service Test mode has the following changes from normal
operation:

S Outdoor air temperature limits for cooling circuits, economizer,

and heating are ignored. Normal compressor time guards and

other staging delays are reduced to 30 seconds or less.

S Circuit alerts are limited to 1 strike (versus 3) before changing to

alarm shut down state.

S The status of ALM.N is ignored so all alerts and alarms are

broadcast on CCN.

S The words “SERVICE TEST” are inserted into every alarm

message.

Service test can only be turned ON/OFF at the unit display. Once
turned ON, other entries may be made with the display or through
CCN. To turn Service Test on, change the value of TEST to ON.
To turn service test off, change the value of TEST to OFF.

IMPORTANT: Service Test mode may be password protected.
Refer to Basic Control Usage section for more information.
Depending on the unit model, factory--installed options, and
field--installed accessories, some of the Service Test functions may
not apply.

Independent Outputs

The independent (INDP) submenu is used to change output status
for the economizer, power exhaust stages, crankcase heaters, and
the alarm relay. These independent outputs can operate
simultaneously with other Service Test modes. All outputs return to
normal operation when Service Test is turned off. When the
economizer is using the factory default Digital Control Type
(Configuration→ECON→E.CTL is 1 or 2) then the Economizer
Calibration feature may be used to automatically check and reset
the economizer actuator range of motion. Refer to the economizer
operation section of more details.

IMPORTANT: If a network force is applied to CCN points:
ECONOCMD, PE_1, PE_2, or ALMOUT, their respective test
mode functions will not be usable. Those forces are at a higher
level than test mode; therefore they will still be honored when in
test mode.

Fan Test

The fans (FANS) submenu is used to change output status for the
indoor fan and outdoor fan stages. The VFD power can be turned
on and off via IDF (Supply VFD Power Test). The indoor fan
speed test (F.SPD) runs the fan at the desired speed entered. The
outdoor fan relay test (OFC.1) only tests the relay for switching
between high and low speeds. The actual outdoor fan will not run
unless cool test is on. The cooling (COOL) and heating (HEAT)
service test outputs are reset to OFF for the fans service test.

SERVICE TEST

10

Cooling Test

The cooling (COOL) submenu is used to change output status for
testing the cooling function. The fans (FANS) and heating (HEAT)
service test outputs are reset to OFF for the cooling service test.
The digital scroll controller power test (CTLR) turns on and off the
compressor controller. The compressor capacity test (CPAC) is
used to run the compressor at a desired capacity of 15% to 100%.
If a capacity is chosen between 1 and 14, the capacity will be set to
15%. The outdoor fan will turn on to high speed when the
compressor capacity is 15% or greater. The indoor fan speed will
default to supply fan maximum speed (FS.MX) when the
compressor capacity test is first activated. The cool test fan speed
(F.SPD) is used to change the fan speed while the compressor is
running. All normal cooling alarms and alerts are functional.

IMPORTANT: When charging the unit, both the compressor
capacity test and the cool test fan speed should be set to 100%.

Heating Test

The heating (HEAT) submenu is used to change output status for
the individual heat stages, gas or electric. The fans (FANS) and
cooling (COOL) service test outputs are reset to OFF for the
heating service test. Indoor and outdoor fans are controlled
normally to maintain proper unit operation. The indoor fan speed
will run at the configured max speed FS.MX. All normal heating
alarms and alerts are functional.

Table 5 — Service Test Modes and Submodes Directory

DISPLAY MENU/
SUB--MENU/
NAME
SERVICE TEST

TEST

INDP Test Independent Outputs

ECON Economizer Position Test 0 to 100%
E.CAL Calibrate Economizer On/Off
PE.1 Power Exhaust 1 Test On/Off
PE.2 Power Exhaust 2 Test On/Off
ALRM Alarm Relay Test On/Off
CCH Crankcase Heat Test On/Off

FANS SUPPLY Te st Fan s

IDF VFD Power Test On/Off
F.SPD Indoor Fan Speed Test 0 to 100%
OFC.1 Outdoor Fan Relay Test On/Off

COOL Test Cooling

CTLR DigScrollCtrlPwrTest On/Off
CAPC Compressor Capacity Test 0 to 100%
F.SPD Cool Test Fan Speed 0 to 100%

HEAT Test Heating

HT.1 Heat Stage 1 Test On/Off
HT.2 Heat Stage 2 Test On/Off

EXPANDED NAME VALUES

Field Service Test Mode On/Off

THIRD PARTY CONTROL

Third party controls may interface with the unit ComfortLinkt
controls through the connections described below. See other
sections of these instructions for more information on the related
unit control and configurations.

Remote Occupancy

The remote occupancy input is provided on the field connection
terminal board (TB1). The Remote Occupancy Switch
configuration, Configuration→UNIT→RM.SW, identifies the
normally open or normally closed status of this input when
unoccupied.

S 5 = 24 VAC signal input
S 6 = 24 VAC source for dry contact

Fire Shutdown

The fire shutdown input is provided for unit shutdown in response
to a fire alarm or smoke detector. The Fire Shutdown Switch
configuration, Configuration→UNIT→FS.SW, identifies the
normally open or normally closed status of this input when there is
no fire alarm.

Input at field connection terminal board (TB1)

S Fire Shutdown 1 = 24 VAC source for dry contact
S Fire Shutdown 2 = 24 VAC signal input

Alarm Output

The alarm output is provided on the field connection terminal
board (TB1) to indicate a current alarm status. The output will be
24VAC if a current alarm exists.

S C=24VACcommon
S X = 24 VAC signal output

Economizer Monitoring

On field terminal board (TB1), terminals 8, 9, and 10 can be used
to monitor economizer position from a third party control system.
See economizer operation section for additional information.

In digital mode (E.CTL = 1 or 2), the economizer commanded
position can be read as a 2--10v or 4--20mA signal. TB1--8 and
TB1--9 are used as follows:

S To read a 2--10v signal, disconnect the violet wire on

TB1--J10--8 and place volt meter device across TB1--8 and

TB1--9.

S To read a 4--20mA signal, disconnect the violet wire on

TB1--J10--8 and the 500Ω resister at TB1--J10--6. Place amp

meter device between TB1--8 and TB1--9.

In analog mode (E.CTL = 3), the economizer position can be read
as a 2--10v feedback signal across TB1 -- 10 and TB1--9 at any time.

IMPORTANT: The violet wire and 500Ω resister must be
connected at the J10 connector as originally wired to operate the
economizer in analog mode.

Economizer Damper Control

For units with the economizer option or accessory and the ECB
control board, the damper position can be directly controlled
through the IAQ sensor input provided on the field connection
terminal board. The IAQ Analog Input configuration,
Configuration→AIR.Q→IA.CF will have to set to 3 (Control
Minimum Position). When IA.CF = 3, an external 4 to 20 mA
source is used to move the damper 0% to 100% directly.

Terminal 2 = 4-- 20mA + signal
Terminal 3 = 4-- 20mA -- common

IMPORTANT: In this mode preset minimum positions
configurations are not valid. The damper position may exceed the
input position to provide economizer cooling and CO

sensor input

2

can not be used for DCV control. Refer to the Indoor Air Quality
operation section for more information.

CONTROLS OPERATION

Display Configuration

The Configuration→DISP submenu is used to configure the local
display settings.

Metric Display (METR)

This variable is used to change the display from English units to
Metric units.

Language Selection (LANG)

This variable is used to change the language of the ComfortLink
display. At this time, only English is available.

48/50PD

11

Password Enable (PROT)

This variable enables or disables the use of a password. The
password is used to restrict use of the control to change
configurations.

Service Password (PSWD)

This variable is the 4-digit numeric password that is required if
enabled.

Test Display LEDs (TEST)

This is used to test the operation of the ComfortLinkt display.

Modes

The ComfortLink controls operate under a hierarchy of command
structure as defined by four main elements: the System Mode, the
HVAC Mode, the Occupied status, and the Unit Control Type.

The System Mode is the top level that defines three main states of
the control system: Disabled, Enabled, or Test.

The HVAC Mode is the next level that defines four main states of
functional operation: Disabled, Fan Only, Cool, and Heat.

The Occupied status affects set points for cooling and heating in
Space Sensor control mode and operation of the economizer for

48/50PD

indoor air quality ventilation and free cooling.
The general operating mode of the control and the status of some

related operation lockouts are located on the display at two
locations: Run Status→ MODE and Operating Modes→ MODE.

System Mode (SYS)

In Run Status and Operating Modes, the current system mode is
displayed with expandable text. This is an overall state of the unit.
Three states are: Unit Operation Disabled, Unit Operation Enabled,
or Service Test Enabled.

HVAC Mode (HVAC)

In Run Status and Operating Modes, the current allowed HVAC
mode is displayed with expandable text. This is the mode the unit
decides to run in based on its inputs. There are four main HVAC
modes; cooling has three different expanded texts. These modes
are shown below.

HVAC

Mode

Disabled HVAC Operation

Fan Only Ventilation

Cooling

Heating Heating Heating mode

Expanded Text Brief Description

Disabled

(fan--only)
Cooling Mechanical cooling
Free Cooling Only economizer used for cooling
Unoccupied Free

Cooling

Unit is in test mode or System mode is
disabled

Fan may run for ventilation

Only economizer use for cooling
(occupied coo ling set point active)

Remote HV AC Mode Disabled (HV.DN)

Allow disabling of HVAC mode. This is only available on a
network connection.

Cool Setpoint in Effect (EFF.C)

This shows the actual setpoint that is being used for control during
cooling mode.

Heat Setpoint in Effect (EFF.H)

This shows the actual setpoint that is being used for control during
heating mode.

Currently Occupied (OCC)

Displays the current state of assumed space occupancy based on
unit configuration and inputs.

Timed Override in Effect (T.OVR)

Displays if the state of occupancy is currently occupied due to an
override.

Linkage Active (LINK)

Displays if Linkage communication is established between the unit
and a Linkage source.

IMPORTANT: The 48/50PD unit only supports the Gen III
TEMP Monitor Thermostat.

Demand Limit in Effect (D.LMT)

Displays if a demand limit has been placed on the unit’s capacity.

Circuit OAT Lockout (C.LOC)

Displays if one or more refrigerant circuits operation is prevented
due to outdoor temperature limit lockout.

Heat OAT Lockout (H.LOC)

Displays if heating operation is prevented due to outdoor
temperature limit lockout.

Econo Cool OAT Lockout (E.LOC)

Displays if economizer operation for cooling is prevented due to
outdoor temperature limit lockout.

Unit Configuration

Many configurations that indicate what factory options and/or field
accessories are installed and other common operation variables are
included in Unit Configuration (Configuration→UNIT).
Configuration will be done at the factory for any factory-installed
option (FIOP).

Start--Up Delay (S.DLY)

This configuration sets the control start-up delay after the power is
interrupted. This can be used to stagger the start-up of multiple
units.

FanOnWhenOccupied(OC.FN)

A YES value will operate the indoor fan whenever the unit is in the
Occupied mode. A NO value will operate the indoor fan only when
heating or cooling is necessary. The factory default value is YES.

Shut Down on IDF Failure (IDF.F)

This configuration applies only if a fan switch is installed and
configured. A YES value will enable diagnostic Alert T409 to shut
down the unit when incorrect fan status is sensed. A NO value will
still permit Alert T409 but will not cause unit shutdown. The
factory default value is YES.

Supply Fan Maximum Speed (FS.MX)

This configuration sets the limit for the highest speed the fan can
run out of 100%. This max speed limit applies to the unit at all
times except for fan test.

Supply Fan Minimum Speed (FS.MN)

This configuration sets the limit for the lowest speed the fan can
run out of 100%. This minimum speed limit applies to the unit
during cooling mode and cooling test.

Vent Mode Fan Speed (FS.VM)

This configuration sets the speed the fan will run during the
ventilation mode. The fan speed does not vary during ventilation
so it will remain at this speed throughout vent mode.

Fan Status Switch (FN.SW)

This configuration identifies if a fan status switch is installed, and
what status (normally open, normally closed) the input is when the
indoor fan is OFF.

Filter Status Switch (FL.SW)

This configuration identifies if a filter status switch is installed, and
what status (normally open, normally closed) the input is when the
filter is CLEAN.

Fire Shutdown Switch (FS.SW)

This configuration identifies if a fire shutdown switch is installed,
and what status (normally open, normally closed) the input is when
the fire or smoke alarm is OFF (no alarm).

Remote Occupancy Switch (RM.SW)

This configuration identifies if a remote occupancy switch is
installed, and what status (normally open, normally closed) the
input is when UNOCCUPIED.

12

RH Sensor On OAQ Input (RH.S)

This configuration identifies if a space relative humidity sensor is
installed on the outdoor air quality (OAQ) input. A YES value
enables SP.RH display. A NO value disables SP.RH display and
use.

Space Humidity Switch (RH.SW)

This configuration identifies if a space relative humidity switch is
installed on the ENTHALPY input, and what status (normally
open, normally closed) the input is when the space humidity is
LOW.

Temperature Compensated Start Cooling Factor
(TCS.C)

This factor is used in the equation of the Temperature
Compensated Start Time Bias for cooling. A setting of 0 minutes
indicates Temperature Compensated Start in Cooling is not
permitted.

Temperature Compensated Start Heating Factor
(TCS.H)

This factor is used in the equation of the Temperature
Compensated Start Time Bias for heating. A setting of 0 minutes
indicates Temperature Compensated Start in Heating is not
permitted.

General Operating Sequence

The PD unit must be connected to a space temperature sensor
T--55, T--56, T58 or T59 and will not operate with a conventional
R, Y1, Y2, W1, W2, G, C thermostat. When a T--55, T--56, T58 or
T59 space temperature sensor is connected to the low voltage
terminal board as shown in the Installation Instructions Manual, the
PD unit will try to maintain the Space Temperature
(Temperatures→AIR.T→SPT) at one of four set points: The
Occupied Cool Set Point (Setpoints→OCSP), the Unoccupied
Cool Set Point (Setpoints→UCSP), Occupied Heat Set Point
(Setpoints→OHSP), or the Unoccupied Heat Set Point
(Setpoints→UHSP).

Occupancy Determination

When the building is in occupied mode, the occupied set points are
active. When the building is in unoccupied mode, the unoccupied
set points are active. The PD control will switch automatically
between cooling and heating to maintain temperature. However, to
minimize unnecessary cool to heat and heat to cool changes, there
is a 10--minute delay after the last stage turns off before the control
will switch modes. The heating and cooling set points are also
separated by a Heat--Cool Set Point Gap (Setpoints→GAP)thatis
user configurable from 2 to 10 degrees F. This parameter prevents
the unit from over cooling the conditioned space to where heating
mode is required or over heating the conditioned space to where
cooling mode is required.

The T55 space temperature sensor senses the temperature in the
conditioned space with no provisions for adjusting the space
temperature set point at the sensor. The T--56 space temperature
sensor senses the temperature in the conditioned space and allows
for adjustment of the space temperature set point by a configurable
number of degrees F higher or a configurable number of degrees F
lower at the space temperature sensor. The T58 space temperature
sensor communicates with the PD unit control board through a
CCN RS--485 +, -- , and ground connection. The T59 space
temperature sensor is a T56 sensor with an integrated temperature
display. A jumper wire is not needed between R and W1 when
using space temperature sensors T55, T56, T58 or T59.

The building’s occupancy is affected by a number of different
factors. When the unit is operating with a space temperature sensor
(T--55, T-- 56, T--58 or T--59), occupancy affects the unit set points
and the operation of the economizer. The factors affecting
occupancy are listed below from highest to lowest priority.

Level 1 Priority

The CCN point OCCUPIED is forced via an external device such
as a ComfortIDt controller: when OCCUPIED is forced to YES,
the unit is considered occupied, when OCCUPIED is forced to
NO, the unit is considered unoccupied. If OCCUPIED is not being
forced, proceed to the level 2 priority.

Level 2 Priority

Remote Occupancy Switch should be configured to either
Normally Open or Normally Closed when the user would like to
control the occupancy with an external switch. This switch is
field-- supplied (24v, single pole, single throw [SPST]). There are
three possible configurations for the remote occupancy switch:

1. (Configuration→UNIT→RM.SW = 0) No Switch

2. (Configuration→UNIT→RM.SW = 1) Normally Open

Switch

3. (Configuration→UNIT→RM.SW = 2) Normally Closed

Switch

If the switch is configured to No Switch (0), the switch input value
will be ignored and software will proceed to level 3 priority. For
each type of switch, the appropriate configuration and states are
listed in the table below.

TYPE OF SWITCH

Occupied when

Closed or

Unoccupied when

Open

Occupied when Open Normal Closed (2)

Unoccupied when

Closed

SWITCH

CONFIGURATION

Normal Open (1)

Normal Closed (2)

STATE OF

SWITCH AND

STATE OF

OCCUPANCY

Open and

Unoccupied

Closed and

Occupied

Open and
Occupied

Closed and

Occupied

IMPORTANT: To perform remote occupancy, an Economizer
Control Board must be installed in the unit.

Level 3 Priority

The following occupancy options are determined by the state of
Occupancy Schedule Number
(Configuration→CCN→SCH.O→SCH.N) and the Global
Schedule Broadcast (Configuration→CCN→BROD→B.GS).

1. (Configuration→CCN→SCH.O→SCH.N = 0) The unit is

always considered occupied and the programmed schedule
is ignored. This is the factory default.

2. (Configuration→CCN→SCH.O→SCH.N = 1- 64) Follow

the local programmed schedule. Schedules 1 to 64 are local
within the controller. The 48/50PD unit can only store one
local schedule and therefore changing this number only
changes the title of the schedule table.

3. (Configuration→CCN→SCH.O→SCH.N = 65- 99)

Follow the global programmed schedule. If the 48/50PD
unit is configured as a Global Schedule Broadcaster
(Configuration→CCN→ROD→B.GS = YES), the unit
will follow the unit’s programmed schedule and broadcast
the schedule so that other devices programmed to follow
this schedule number can receive the schedule. If the
48/50PD unit is not programmed as a Global Schedule
Broadcaster
(Configuration→CCN→BROD→B.GS = NO), the unit
will receive broadcasted schedules from the unit
programmed to broadcast this schedule number. While
using the programmed schedule, occupancy can be
temporarily switched from unoccupied to occupied by
pressing the override button for approximately 3 seconds on
the T--55, T-- 56, T -- 58 or T --59 space temperature sensor.
Override will only occur if SPT Override Enabled

48/50PD

13

(Configuration→CCN→SCH.O→OV.SP) is set to YES.
The length of the override period is determined by the
Timed Override Hours setting
(Configuration→CCN→SCH.O→OV>EX).

Compressor Operation

The 48/50 PD units use a Copeland Digital Scroll Compressor that
can vary the refrigerant capacity between 100 and 15%. This is
accomplished by a mechanism in the compressor that separates the
two scroll spirals which stops the pumping of the refrigerant gas.
This mechanism is operated by the differential pressure between
the suction and discharge of the compressor. The pressure to
operate the unloading mechanism is controlled by a small solenoid
situated in a refrigerant line between the top of the compressor and
the suction line. When the solenoid is energized the compressor is
unloaded. The solenoid coil is controlled by the Copeland Digital
Scroll Controller (DSC) that operates on a 1 to 5V signal from the
ComfortLink Auxiliary Board (AUX1) and converts this into a
Pulse Width Modulated (PWM) signal to the solenoid valve. The
pulse width modulated signal is an on and off signal that repeats
every 15 seconds with the off time portion of the 15 seconds
representing the % loading of the compressor.

48/50PD

The Compressor Capacity (Outputs→COOL→CAPC) can be
monitored on the ComfortLink Scrolling Marquee Display. The
Compressor Capacity value is determined by a Proportional,
Integral, Derivative (PID) algorithm that controls the Supply Air
Temperature (Temperatures→AIR.T→SAT) to the Supply Air
Control Point (Run Status→COOL→SA.CP).

The Compressor Minimum Capacity
(Configuration→COOL→MIN.C) is configured at the factory to
70%. This is the minimum compressor capacity that gives the
highest SEER rating for a 48 series unit with the highest gas heat
option and no economizer per AHRI standard 210/240. Since the
AHRI rating standard does not account for energy savings that can
be realized by displacement ventilation air distribution system and
extending economizer cooling operation at higher supply air
temperature set points, a complete energy analysis should be
conducted before changing the Compressor Minimum Capacity
(Configuration→COOL→MIN.C) setting to determine the energy
savings at a lower Compressor Minimum Capacity
(Configuration→COOL→MIN.C) setting.

Indoor Fan Operation

The indoor fan is controlled by the Indoor Fan VFD Power Relay
(Outputs→FANS→IDF) on the MBB (main base board) control,
which then operates the indoor fan contactor (IFC). On the
48/50PD units the Indoor Fan VFD Power Relay
(Outputs→FANS→IDF) is always on so that power is supplied to
the VFD electronic boards. This prevents the formation of
condensation on the VFD electronic boards and provides power to
the remote VFD display so that error codes and VFD configuration
parameters can be verified.

The 48/50PD unit controls require an accurate supply duct CFM at
the unit design point where the indoor fan will run at the Supply
Fan Maximum Speed (Configuration→UNIT→FS.MX).The
Supply Fan Maximum Speed (Configuration→UNIT→FS.MX)
is used for operation of the economizer and power exhaust. The
supply duct CFM is configured by the Indoor Fan Max Speed
CFM (Configuration→ECON→IDF .C). Default values for
Indoor Fan Max Speed CFM (Configuration→ECON→IDF.C)
are at 400 CFM per ton or 1600 CFM for the 05 size and 2000
CFM for the 06 size. It is preferred to use the supply duct CFM
from an air balance report to configure the Indoor Fan Max Speed
CFM (Configuration→ECON→IDF.C). If an air balance report
is not available then use the fan tables supplied in this book to
determine Fan Max Speed CFM
(Configuration→ECON→IDF.C). When using the fan tables to
determine Fan Max Speed CFM

(Configuration→ECON→IDF.C) set Economizer Position Test

(Service Test→INDP→ECON) to 0 (Economizer Damper Closed)
and Indoor Fan Speed Test (Service Tes→FAN S →F. S P D ) equal to
(Configuration→UNIT→FS.MX). Measure the supply to return

duct static pressure difference and indoor fan RPM. Make
correction to static pressure for all options installed in the unit per
the accessory pressure drop table. Determine Indoor Fan Max
Speed CFM (Configuration→ECON→IDF.C)
where the corrected static pressure and RPM cross.

The supply fan speed range is configured by the Supply Fan
Maximum Speed (Configuration→UNIT→FS.MX) and the
Supply Fan Minimum Speed (Configuration→UNIT→FS.MN).
These configuration values are in units of % speed referenced to a
2 to 10VDC signal to the VFD AI1 input with 2VDC representing
0% speed and 10VDC representing 100% speed or 0 to 60HZ
VFD frequency output to the motor.

The Supply Fan Minimum Speed
(Configuration→UNIT→FS.MN) can be user configured
between 10 and 70%. The Supply Fan Minimum Speed default
value is 70%, this provides the greatest energy efficiency rating for
a unit without an economizer in a mixed air type duct application.

The Supply Fan Maximum Speed
(Configuration→UNIT→FS.MX) can be configured between 80
and 100%. The Supply Fan Maximum Speed default value is
100%. Set the indoor fan pulley to the application design point
CFM for heating and cooling at 100% fan speed so that the CFM is
not lower than the minimum CFM allowed in the product data. If
the exact CFM can not be set by the half turn pulley settings then
adjust the Supply Fan Maximum Speed
(Configuration→UNIT→FS.MX) to fine tune the CFM to the
application requirements. The Supply Fan Maximum Speed
(Configuration→UNIT→FS.MX) RPM must now produce
supply CFM that is not lower that the minimum CFM allowed in
the product data for heating and cooling.

The indoor fan may operate during cooling with compressors
mode, free cooling with outdoor air mode, heating mode, or for
ventilation with outdoor air mode.

The indoor fan operation can be affected by the following:

S FanOnWhenOccupied(Configuration→UNIT→OC.FN)
S IAQ Analog Fan Config (Configuration→AIR.Q→IA.FN)
S IAQ Switch Fan Config (Configuration→AIR.Q→II.FN)
S Fan Status Switch (Configuration→UNIT→FN.SW)

When the unit is in occupied or unoccupied cooling mode the
supply fan will modulate to maintain the space temperature sensor
set point between the configured Supply Fan Maximum Speed
(Configuration→UNIT→FS.MX) and the Supply Fan Minimum
Speed (Configuration

When the 40PD or 50 PD unit is in occupied or unoccupied
heating mode (gas heat or electric heat mode) the indoor fan will
operate at the Supply Fan Maximum Speed
(Configuration→UNIT→FS.MX) setting.

For 48PD gas heating units, the IGC control fan output is also
monitored by the MBB control. This can result in additional
modifications of fan delays or other operation due to safety
functions of the IGC control.

When the PD unit is in free cooling mode the indoor fan will
modulate to maintain The Occupied Cool Set Point

(Setpoints→OCSP), the Unoccupied Cool Set Point
(Setpoints→UCSP), Occupied Heat Set Point
(Setpoints→OHSP), or the Unoccupied Heat Set Point
(Setpoints→UHSP).

When the PD unit is in ventilation mode and Fan On When
Occupied (Configuration→UNIT→OC.FN) the indoor fan will
operate at the Vent Mode Fan Speed

(Configuration→UNIT→FS.VM). Vent Mode Fan Speed
(Configuration→UNIT→FS.VM) factory default is 50% and can

be user configured between 40 and 100%.

→UNIT→FS.MN).

on the fan table

14

Outdoor Fan Operation

The 48/50 PD units use a multi--speed outdoor fan motor to control
the head pressure within an acceptable range at low outdoor
ambient temperatures. On the 48 and 50 PD--05 and 06 size units
the outdoor fan contactor is powered on the load side of the
compressor contactor so the outdoor fans will run only when the
compressor contactor is energized. When the outdoor fan
contactor is not energized the outdoor fan runs at high speed.

When the outdoor fan contactor is energized the outdoor fan runs
at low speed.

The outdoor fan speed is controlled by a system three of fan levels
set up in the control software. Table 6 shows the three levels and
fan speeds for each level. The fan levels are determined by
Outdoor Air Temperature (Temperatures→AIR.T→OAT) but can
be overridden by Condenser Pressure A (Pressures→SCP.A)
inputs to the Main Base Board.

FAN

LEVEL

0 OFF N/A

1 LOW 1. Compressor Contactor is OFF

2 HIGH

FAN

SPEED

CONDITIONS TO TRANSITION TO NEXT

LOWER LEVEL

1 . O u t s i d e A i r Te m p e r a t u r e C o n t r o l --- --- F a n
Lev2 Off Temperature 45 F or below (Confi-

guration→COOL→OFC→2.OFF <=45F)*

2. Condenser Pressure A Override --- --- Fan
Lev2 Min Pressure 200 psig or below (Config-

uration→COOL→OFC→2.MNP<= 200 psig)*

CONDITIONS TO TRANSITION TO NEXT

HIGHER LEVEL

1. Compressor Contactor is ON

(on initial start up outdoor fan runs at Level 2 for
10 seconds before moving to correct level based
on outside air temperature or Condenser Pres­sure A)

1. Outside Air Temperature Control — Fan
Lev2 On Temperature 55 F or above (Configu-

ration→COOL→OFC→2.ON >=55F)*

2. Condenser Pressure A Override — Fan
Lev1 Max Pressure 450 psig or above (Config-

uration→COOL→OFC→1.MXP>= 450 psig)*

N/A

Table 6 — Fan Level Control of Outdoor Fan

*Configuration parameters 1.MXP, 2.MNP, 2.ON and 2.OFF factory default configuration should not be changed. The default configurations have been qualified over a wide
range of conditions and are provided in case a field replacement of the control board o ccurs and the settings need to be check ed or manually conf igured.\

Economizer Operation

If an economizer is installed, then Economizer Installed
(Configuration→UNIT→EC.EN) should be set to YES. The
economizer is controlled by the Econo Commanded Position
(Outputs→ECON→EC.CP) on the Economizer Control Board
(ECB). Feed back from the economizer actuator is output on
configuration parameter Econo Actual Position
(Outputs→ECON→EC.AP).

Economizer Actuator

The economizer actuator used with the 48/50PD units is a
Multi--Function Technology (MFT) actuator. This allows the
ComfortLink system to communicate with the actuator through a
feedback signal. The configuration Economizer Control Type
(Configuration→ECON→E.CTL) determines the communication
method, either digital or analog, used to communicate between the
Economizer Control Board and the economizer actuator.

The power to the unit must be cycled after the Economizer Control
Type (Configuration →ECON→E.CTL) configuration parameter
is changed.

E.CTL = 1 or 2 (Digital/Position or Digital/Command)

When Economizer Control Type
(Configuration→ECON→E.CTL) is set to 1, the Economizer
Control Board will communicate with the economizer actuator
using the digital protocol, from Economizer Control Board plug
J7--1 to actuator pin 5. The commanded position and the actuators
actual position are communicated back and forth between the
actuator and the Economizer Control Board. When the Economizer
Control Board and actuator first initiate communication, a Control
Angle Economizer Control Type (Operating Modes→
ECON→C.ANG) is provided to the Economizer Control Board
and defines the actuator’s range of motion. The control angle must
be greater than the Min Actuator Ctrl Angle
(Configuration→ECON→M.ANG). During this digital control,
the Economizer Control Board analog 4 to 20 mA output will
represent the actuator’s actual position when E.CTL = 1 or

Communication

commanded position when E.CTL = 2. Because the wiring has a
built--in 500 -- ohm resistor, the 4 to 20mA signal is converted to a 2
to 10VDC signal that is accessible via a field connected terminal
board TB--8 and TB-- 9. However, before this signal can be read
remotely, the violet wire that connects the actuator to field
connection terminal board TB--J10--8 must be removed or cut.

E.CTL = 3 (Analog Control)

When E.CTL is set to 3, the Economizer Control Board will NOT
communicate with the economizer actuator directly with the 4 to
20mA analog signal wired to TB--8 and TB -- 9 along with the
500--ohm resistor producing a 2 to 10VDC signal for the actuator.
While in this mode, the actuator’s built--in 2 to 10VDC feedback
signal s accessible via TB--9 and TB--10 any time because it is not
used by the Economizer Control Board.

Cooling

Free

The economizer will be allowed to help with cooling if the
Outdoor Air Temperature (Temperatures→AIR.T→OAT) is less
than the configured Econo Cool Hi Temp Limit
(Configuration→ECON→EH.LO) and greater than the
configured Econo Cool Lo Temp Limit
(Configuration→ECON→EL.LO). If an enthalpy sensor is
installed, the outdoor temperature must be below the Econo Cool
Hi Temp Limit (Configuration→ECON→EH.LO) and the
Outdoor Enthalpy Switch (Inputs→GEN.I→ENTH) must be
LOW.

Unoccupied Free Cooling

The unoccupied free cooling algorithm attempts to maintain the
building space half way between the Occupied Cool Set Point

(Setpoints→OCSP) and Occupied Heat Set Point
(Setpoints→OHSP) using only the economizer when the

conditions in the building and the outdoors are suitable., during
UNoccupied periods if the air in the building and the outdoor air
are suitable. Three different configurations define this algorithm:

1. Unoccupied Free Cooling

(Configuration→ECON→UEFC)

48/50PD

15

a. (Configuration→ECON→UEFC = 0) -- D i s a b l e d

When UEFC = 0, unoccupied free cooling is disabled.
Cooling will only occur if the space exceeds the
unoccupied setpoints.

b. (Configuration→ECON→UEFC = 1) -- Unoccupied

When UEFC is set to 1, unoccupied free cooling can
occur throughout the entire unoccupied period. The
space temperature must be higher then the mid--point
between the occupied cooling and heating set points.

c. (Configuration→ECON→UEFC = 2) -- Preoccupancy

When UEFC is set to 2, unoccupied free cooling can
only occur when the time until the next occupied period
is less than the Free Cool PreOcc Time (FC.TM) in
minutes.

2. Free Cool PreOcc Time

(Configuration→ECON→FC.TM)

FC.TM is the configuration that determines how many
minutes before occupancy that free cooling can occur when
set for Preoccupancy (UEFC = 2).

3. 1.Free Cool Low Temp Limit

(Configuration→ECON→FC.LO)

48/50PD

Unoccupied free cooling cannot occur if the Outdoor Air
Temperature (Temperature→ AIR.T→ OAT) is less than
FC.LO.

Exhaust

Power

To enable power exhaust set Power Exhaust Installed
(Configuration→ECON→PE.EN) to YES. On the 48/50PD--05
and 06 size units both power exhaust fans are wired together and
are controlled by the configuration Power Exhaust Stage1 CFM
(Configuration→ECON→PE1.C). When the Indoor Fan Max
Speed CFM (Configuration→ECON→IDF.C) is set to the correct
supply duct CFM (either by fan tables or air balance report) the
control will calculate the outside air CFM based on outside air
damper position and Commanded Fan Speed
(Outputs→FANS→F. S P D ) to turn on the power exhaust when the
calculated outside air CFM reaches Power Exhaust Stage1 CFM
(Configuration→ECON→PE1.C). The power exhaust will turn
off when the calculated outside air CFM falls below Power
Exhaust Stage1 CFM (Configuration→ECON→PE1.C).The
Power Exhaust Stage2 CFM (Configuration→ECON→PE2.C) is
not currently used on the 48/50PD--05 and 06 units.

Indoor Air Quality (IAQ)

The ComfortLink TM control has the capability for several
methods of demand ventilation control. Indoor air quality is
typically measured using a CO2 sensor whose measurements are
displayed in parts per million (ppm). Outdoor air quality may be
measured with a CO2 sensor for indoor--outdoor differential
demand ventilation control, or with other sensor types for the
outdoor air lockout function. The factory--installed indoor air
quality CO2 sensor is mounted in the return section. A
field-- installed indoor air quality CO2 sensor may be mounted in
the return or directly in the occupied space, per job requirements.
The indoor air quality modes of operation can be affected by the
IAQ Analog Input Config (Configuration→ AIR.Q→ IA.CF),
IAQ Switch Input Config (Configuration→ AIR.Q→ IA.CF),
OAQ Analog Input Config (Configuration→ AIR.Q→ OA.CF)
and other related fan and limit configurations as described below.

IAQ (Analog

The ComfortLink TM control is configured for indoor air quality
sensors which provide 4 to 20 mA signal for 0 to 2000 ppm CO2.
If the sensor being used has a different range, the ppm display
range must be reconfigured by entering new values for the IAQ
Sensor Value at 4mA (Configuration→AIR.Q→I.4M) and IAQ
Sensor Value at 20mA (Configuration→AIR.Q→I.20M).

IA.CF = 0 (No IAQ)

IA.CF = 0 signifies that there is no IAQ sensor installed. The
damper will operate at the Econ Min at Max Fan Speed

Input)

(Configuration→ECON→MP.MX) when the fan is at Supply Fan
Maximum Speed (Configuration→UNIT→FS.MX) and the
damper position will vary at other fan speeds as described in the
Cooling Mode with Economizer section below when the space is
occupied and the indoor fan is on.

IA.CF = 1 (DCV)

When IA.CF = 1 the IAQ algorithm is set for Demand Control
Ventilation (DCV). During DCV, the damper modulates between
two user configurations depending upon the relationship between
the Indoor Air Quality (IAQ) and the Outdoor Air Quality (OAQ).
The lower of these two positions is referred to as the Econo Min
IAQ Position (Configuration→AIR.Q→AQ.MN) while the higher
is referred to as the Econ Min at Max Fan Speed
(Configuration→ECON→MP.MX). The Econo Min IAQ
Position (Configuration→AIR.Q→AQ.MN) should be set to an
economizer position that brings in enough fresh air to remove
contaminates and CO2 generated by sources other than people.
The Econ Min at Max Fan Speed
(Configuration→ECON→MP.MX) should be set to an
economizer position that brings in fresh air to remove contaminates
and CO2 generated by all sources including people when the
indoor fan is operating at the Supply Fan Maximum Speed
(Configuration→UNIT→FS.MX). The Econ Min at Max Fan
Speed (Configuration→ECON→MP.MX) value is the design
value for maximum occupancy.

The ComfortLink TM control will begin to open the damper from
the Econo Min IAQ Position (Configuration→AIR.Q→AQ.MN)
position when the IAQ level begins to exceed the Outdoor Air
Quality (OAQ) level by a configurable amount. This amount is
referred to as AQ Differential Low
(Configuration→AIR.Q→AQD.L). When the differential
between IAQ and OAQ reaches AQ Differential High
(Configuration→AIR.Q→AQD.H), the economizer position will
be at the Econ Min at Max Fan Speed
(Configuration→ECON→MP.MX) when the indoor fan speed is
at Supply Fan Maximum Speed
(Configuration→UNIT→FS.MX). When the IAQ/OAQ
differential is between AQ Differential Low

(Configuration→AIR.Q→AQD.L) and AQ Differential High
(Configuration→AIR.Q→AQD.H), the control will modulate the

damper between Econ Min at Max Fan Speed

(Configuration→ECON→MP.MX) and Econo Min IAQ Position
(Configuration→AIR.Q→AQ.MN) in a linear manner as shown

in Figure 3. At other fan speeds the economizer damper will
operate in the shaded area between the two economizer position
curves but at the actual fan speed as indicated by Commanded Fan
Speed (Outputs→FANS→F. S P D ) .

IA.CF = 2 (Override IAQ)

When IA.CF = 2, the IAQ algorithm maintains the damper at Econ
Min at Max Fan Speed (Configuration→ECON→MP.MX) wh en
the indoor fan speed is at Supply Fan Maximum Speed
(Configuration→UNIT→FS.MX) or in the shaded area of Figure
3 when the indoor fan speed is at the Commanded Fan Speed
(Outputs→FANS→F. S P D ) until the override condition triggers.
The override triggers when the IAQ/OAQ differential is greater
than AQ Differential High
The IAQ Override Position (Configuration→AIR.Q→OVR.P).
The economizer damper will return to the Econ Min at Max Fan
Speed (Configuration→ECON→MP.MX) or MP.MX curve at
other fan speeds when the IAQ/OAQ differential is less than the
AQ Differential Low (Configuration→AIR.Q→AQD.L).

The override algorithm will operate whenever the building is
occupied and the indoor fan is operating or whenever the IAQ
algorithm has caused the indoor fan to operate. The IAQ Analog
Fan Config (Configuration→AIR.Q→IA.FN) determines whether
or not the IAQ algorithm can turn on the indoor fan.

If the indoor fan is not operating, the economizer position will be
zero. If the override is not active and the building is unoccupied,
the economizer position will be zero. The damper position may

(Configuration→AIR.Q→AQD.H).

16

exceed Econ Min at Max Fan Speed

(Configuration→ECON→MP.MX) or IAQ Override Position
(Configuration→AIR.Q→OVR.P) to provide economizer

cooling.

IA.CF = 3 (Control Minimum Position)

When IA.CF = 3, an external 4 to 20 mA source is used to set the
minimum position. The 4mA signal corresponds to 0% and the 20
mA signal corresponds to 100%. In this mode, configuration such
as Econ Min at Max Fan Speed

(Configuration→ECON→MP.MX), Econo Min IAQ Position
(Configuration→AIR.Q→AQ.MN) and the economizer minimum

position and DCV minimum position curves in figure 3 are not
used.

If the indoor fan is not operating, the economizer position will be
zero. The damper position may exceed the economizer minimum
position to provide economizer cooling.

IAQ (Switch

Indoor air quality can also be measured using a switch input. For
the purpose of specifying the type of switch input, low CO2 levels
are considered normal. The IAQ switch input is defined by the
IAQ Switch Input Config (Configuration→AIR.Q→II.CF).
Enthalpy and IAQ are controlled by the same switch input and
therefore cannot be used simultaneously.

II.CF = 0 (NO IAQ)

The II.CF = 0, configuration signifies that there is no IAQ switch
input. The damper will operate at the Econ Min at Max Fan Speed
(Configuration→ECON→MP.MX) and corresponding damper
position curve based on indoor fan speed when the space is
occupied and the indoor fan is on.

II.CF = 1 (DCV Normally Open)
II.CF = 2 (DCV Normally Closed)

The Demand Control Ventilation (DCV) allows the economizer
minimum position to be decreased when there is no IAQ problem.
If IAQ is low, the economizer minimum position is Econo Min
IAQ Position (Configuration→AIR.Q→AQ.MN) when the indoor
fan is operating at Supply Fan Maximum Speed
(Configuration→UNIT→FS.MX). If IAQ is high, the
economizer minimum position is Econ Min at Max Fan Speed
(Configuration→ECON→MP.MX) when the indoor fan is
operating at Supply Fan Maximum Speed
(Configuration→UNIT→FS.MX).

II.CF = 3 (Override Normally Open)
II.CF = 4 (Override Normally Closed)

The damper override function permits absolute positioning of the
economizer damper for ventilation purposes. The override is
active when IAQ is high and inactive when IAQ is low. The
override position is configured by the IAQ Override Position
(Configuration→AIR.Q→OVR.P).

Outdoor Air Quality (Analog

The ComfortLink TM control is configured for outdoor air quality
sensors which provide a 4 to 20 mA signal corresponding to 0 to
2000 ppm CO2. If a field supplied sensor has a different range, the
ppm display range must be reconfigured by entering new values
for the OAQ Sensor Value at 4mA
(Configuration→AIR.Q→O.4M) and OAQ Sensor Value at
20mA (Configuration→AIR.Q→O.20M).

OA.CF = 0 (NO OAQ)

This signifies that there is no outdoor air sensor installed. The
default value of OAQ is 400 ppm CO2.

OA.CF = 1 (DCV)

The outdoor air quality sensor analog input is the value of OAQ.

OA.CF = 2 (OAQ Lockout)

The outdoor air quality analog input is only used to lock out the
outdoor ventilation. The economizer commanded position is set to
0% when the CO2 ppm exceeds the OAQ lockout value
configured for the OAQ Lockout Limit
(Configuration→AIR.Q→AQ.L). The default value for OAQ

Input)

Input)

Lockout Limit (Configuration→AIR.Q→OAQ.L) is 600 ppm
CO2.

Fan Enable (Analog IAQ

The DCV algorithm will operate whenever the building is
occupied and the indoor fan is operating or whenever the IAQ
algorithm has caused the indoor fan to operate. The IAQ Analog
Fan Config (Configuration→AIR.Q→IA.FN) determines
whether or not the IAQ algorithm can turn on the indoor fan. If the
indoor fan is not operating, the economizer position will be zero.
The damper position may exceed Econ Min at Max Fan Speed
(Configuration→ECON→MP.MX) and corresponding damper
position curve to provide economizer cooling.

IA.FN = 0 (Never)

When IA.FN =0, the IAQ algorithm can never turn on the fan.

IA.FN = 1 (Occupied)

When IA.FN =1, the IAQ algorithm will turn on the indoor fan
whenever the building is occupied and IAQ/OAQ differential is
greater than the Fan On AQ Differential
(Configuration→AIR.Q→DF.ON). The indoor fan will turn off
when the IAQ/OAQ differential is less than the Fan Off AQ
Differential (Configuration→AIR.Q→DF.OF).

IA.FN = 2 (Always)

The indoor fan operation for IA.FN =2,isthesameasthe
operation when IA.FN =1, except the algorithm is not limited to
the occupied periods only. The fan can be triggered on when the
space is occupied or unoccupied.

Fan Enable (Analog Switch

The DCV algorithm will operate whenever the building is
occupied and the indoor fan is operating or whenever the IAQ
algorithm has caused the indoor fan to operate. The IAQ Switch
Fan Config (Configuration→AIR.Q→II.FN) determines whether
or not the IAQ algorithm can turn on the indoor fan. If the indoor
fan is not operating, the economizer position will be zero. The
damper position may exceed Econ Min at Max Fan Speed
(Configuration→ECON→MP.MX) and corresponding damper
position curve to provide economizer cooling.

II.FN = 0 (Never)

When II.FN =0, the IAQ algorithm can never turn on the fan.

II.FN = 1 (Occupied)

When II.FN =1, the IAQ algorithm will turn on the indoor fan
whenever the building is occupied and IAQ is high. The indoor
fan will turn off when the IAQ returns to normal.

II.FN = 2 (Always)

The indoor fan operation for II.FN =2, is the same as the operation
when IA.FN =1, except the algorithm is not limited to the
occupied periods only. The fan can be triggered on when the space
is occupied or unoccupied.

Sensor)

Input)

Cooling Modes

Cooling Mode Using Space Temperature Sensor T55,
T56, T58 or T59

In cooling mode the PD control will maintain the Occupied Cool
Set Point (Setpoint→OCSP) or the Unoccupied Cool Set Point
(Setpoints→UCSP) by modulating the indoor fan speed to supply
more or less airflow to the conditioned space at the Supply Air
Temperature (Temperatures→AIR.T→SAT).

Cooling Supply Air Set

The Cool Supply Air Set Point (Setpoint→SASP)can be
configured between 45F and 75F. The compressor modulates to
maintain a Supply Air Temperature

(Temperatures→AIR.T→SAT)at the Cool Supply Air Set Point
(Setpoint→SASP).

Cooling Speed Demand W

When the temperature in the conditioned space is higher than the
Occupied Cool Set Point (Setpoints→OCSP) plus the Fan Speed
Control Demand (Configuration→COOL?FS.CD) configuration

Point

indow

48/50PD

17

variable or Unoccupied Cool Set Point (Setpoints→UCSP) plus
the Fan Speed Control Demand
(Configuration→COOL→FS.CD) configuration variable the
indoor fan will run at 100%. When the temperature in the
conditioned space is between the Occupied Cool Set Point

(Setpoints→OCSP) and Occupied Cool Set Point
(Setpoints→OCSP) plus the Fan Speed Control Demand
(Configuration→COOL→FS.CD) configuration variable the

indoor fan modulates to satisfy the Occupied Cool Set Point

(Setpoints→OCSP) or Unoccupied Cool Set Point
(Setpoints→UCSP). When the temperature in the conditioned

space falls to 0.5F below the Occupied Cool Set Point

(Setpoints→OCSP) or Unoccupied Cool Set Point
(Setpoints→UCSP) for 5 minutes the controls will run unit in

ventilation mode. See ventilation mode sequence of operation.

can be set to --10 and the SASP Maximum Reset Up
(Configuration→COOL→SAT→SA.MU) configuration variable
can be set to 0 giving the range of Cool Supply Air Set Point
(Setpoint→SASP) reset of +0 and --10 F.

In normal operation when the Space Temperature is within the
speed demand window the unit control will modulate the indoor
fan speed and supply air temperature along a defined curve to bring
the Space Temperature to Occupied or Unoccupied Cool Set Point.
Since this curve is independent of the conditioned space load the
control scheme will adapt to any load present in the conditioned
space by adjusting the fan speed and supply air temperature and
move the space temperature along the defined time temperature
curve to Occupied or Unoccupied Cool Set Point.

When the space temperature rises above the Occupied Cool Set
Point (Setpoints→OCSP) + Fan Speed Control Demand
(Configuration→COOL→FS.CD) for over 2 minutes or is outside
the speed demand window and there is some amount of SASP
Maximum Reset Down (Configuration→COOL?SAT→SA.MD)
configured the indoor fan will be locked at 100% and the unit
controls will subtract a calculated amount of temperature reset to
the Cool Supply Air Set Point (Setpoint

48/50PD

speed will be locked at 100% as long as reset is applied. The
Supply Air Temperature will now adjust to this new Supply Air

→SASP). The indoor fan

Control Point (Run Status→COOL→SA.CP). The controls will
continue to subtract a calculated amount of temperature reset
cumulatively to a value equal to the Supply Air Temperature Set

C09143

Fig. 6 -- Cooling Speed Demand Window

Cooling Supply Air Set Point

Reset

The PD unit can be configured to allow for reset of the Cool
Supply Air Set Point (Setpoint→SASP). This is needed for
applications where a high Cool Supply Air Set Point
(Setpoint→SASP) is required or where dramatic load changes
occur over short time periods. In these situations a high supply air
temperature may not provide enough cooling to reduce the Space

Point (Setpoint→SASP) + SASP Maximum Reset Down
(Configuration→COOL→SAT→SA.MD). When the reset is no
longer needed the control will remove Down Reset until all reset is
removed and the Supply Air Control Point (Run
Status→COOL→SA.CP) is back to the original Supply Air Set
Point (Setpoint→SASP). The indoor fan will then modulate lower
than 100% to move the Space Temperature (Temperatures→SPT)
along the defined time temperature curve to Cool Supply Air Set
Point (Setpoint→SASP) or Unoccupied Cool Set Point
(Setpoints→UCSP). See Fig. 6 and 7.

Temperature (Temperatures→AIR.T→SPT) to the Occupied Cool
Set Point (Setpoints→OCSP) or the Unoccupied Cool Set Point
(Setpoints→UCSP) over a reasonable time period.

The compressor or economizer operation supplying cooling to the
conditioned space controls to the Supply Air Control Point (Run

Status→COOL→SA.CP). The Supply Air Control Point (Run
Status→COOL→SA.CP) which is a calculated value that is equal

to the Cool Supply Air Set Point (Setpoint→SASP) plus the
calculated amount of reset required up to the values set by
configuration variables SASP Maximum Reset Down
(Configuration→COOL→SAT→SA.MD) and SASP Maximum
Reset Up (Configuration→COOL→SAT→SA.MU).

Reset of the Cool Supply Air Set Point (Setpoint→SASP) is

Fig. 7 -- Cool Supply Air Set Point

C09144

limited by the configuration variables SASP Maximum Reset
Down (Configuration→COOL→SAT→SA.MD) and SASP
Maximum Reset Up (Configuration→COOL→SAT→SA.MU).
The SASP Maximum Reset Down

(Configuration→COOL→SAT→SA.MD)

configuration variable

can be set from --20 to 0 F and will allow the Cool Supply Air Set
Point (Setpoint→SASP) to be reset to as much as 20 F below the
Cool Supply Air Set Point (Setpoint→SASP). The SASP
Maximum Reset Up (Configuration→COOL?SAT→SA.MU)
configuration variable can be set from 0 to 20 F and will allow the
Supply Air Temperature to be Reset to as much as 20 F above the
Cool Supply Air Set Point (Setpoint→SASP). The SASP
Maximum Reset Down (Configuration→COOL →SAT→SA.MD)
and SASP Maximum Reset Up
(Configuration→COOL→SAT→SA.MU) configuration variables
can be set independently and do not need to be equal values above

Cooling Mode with Economizer Using Space
Temperature Sensor T55, T56, T58 or T59

If an economizer is installed, the Economizer Installed
configuration (Configuration→ECON→ EC.EN) should be set to
YES. The economizer is controlled by the Econo Commanded
Position (Outputs→ECON→ EC.CP) on the Economizer Control
Board. If the indoor fan is off or the building is unoccupied, the
economizer position is zero.

When the space temperature is above the Occupied Cool Set Point
(Setpoints→OCSP) and the economizer is installed, configured
and working correctly the unit controls will always try to meet
space cooling demand using the economizer before turning on the
compressor. The economizer will provide free cooling when the
following outside air conditions are true.

and below the Cool Supply Air Set Point (Setpoint→SASP).For
example, the SASP Maximum Reset Down
(Configuration→COOL→SAT→?SA.MD) configuration variable

18

For all units with Economizers:

1. 1.The outdoor temperature is below the Econo Cool Hi
Temp Limit (Configuration→ECON→EH.LO) and above
the Econo Cool Lo Temp Limit
(Configuration→ECON→EL.LO).

For units with Enthalpy Control

2. 1.The outdoor enthalpy is low and the outdoor temperature
is below the Econo Cool Hi Temp Limit
(Configuration→ECON→EH.LO) and above the Econo
Cool Lo Temp Limit (Configuration→ECON→EL.LO).

If the conditions above are true and the economizer is available for
cooling the economizer outside air and return air dampers will
modulate to allow proportions of outside air and return air to mix
and produce a temperature equal to the Cool Supply Air Set Point
(Setpoint→SASP). If reset is applied to the Supply Air
Temperature Set Point (Setpoint→SASP) the dampers will control
to the Supply Air Control Point (Run Status→COOL→SA.CP).

If the conditions above are true but the economizer dampers are not
able to satisfy the Cool Supply Air Set Point (Setpoint→SASP)
with Reset (if applied), the compressor will turn on and modulate
to provide additional cooling to satisfy the Cool Supply Air Set
Point (Setpoint→SASP) with Reset if applied.

If the conditions above are not true, the economizer will move to a
user Configurable Econ Min at Max Fan Speed
(Configuration→ECON→MP.MX) where the minimum
economizer damper position is based on the Supply Fan Maximum
Speed (Configuration→UNIT→FS.MX). This is done to
maintain a constant airflow through the economizer by opening the
dampers more as the indoor fan speed is reduced or closing the
dampers more as the indoor fan speed increases.

The shape of the Economizer Minimum Position vs. Fan Speed
curve is determined by the configuration parameters: Econ Min at
25% Fan speed (Configuration→ECON→MP.25), Econ Min at
50% Fan speed (Configuration→ECON→MP.50), Econ Min at
75% Fan speed (Configuration→ECON→MP.75) and Econ Min
at Max Fan speed (Configuration→ECON→MP.MX).

The Econ Min at 25% Fan speed

(Configuration→ECON→MP.25), Econ Min at 50% Fan speed
(Configuration→ECON→MP.50) and Econ Min at 75% Fan

speed (Configuration→ECON→MP.75) damper positions are
calculated based on the Econ Min at Max Fan Speed
(Configuration→ECON→MP.MX) and Supply Fan Maximum
Speed (Configuration→UNIT→FS.MX).

The Econ Min at 25% Fan speed

(Configuration→ECON→MP.25), Econ Min at 50% Fan speed
(Configuration→ECON→MP.50) and Econ Min at 75% Fan

speed (Configuration→ECON→MP.75) damper position are user
configurable and can be determined by setting the fan speed at 25,
50 and 75% and determining the damper position required to
maintain the Econ Min at Max Fan Speed
(Configuration→ECON→MP.MX) Outside air CFM through the
economizer outside air dampers. The default calculations
programmed into the PD controls is based on a side shot
economizer at 400 CFM/TON Supply Air flow with negative 0.25

O pressure in the return duct.

in H

2

Econ Min at Max fan Speed (Configuration→UNIT→FS.MN) is
set by user based on minimum required outside air ventilation
CFM required for the application. This procedure would be the
same as if this were a CV unit with the unit running at the design
point CFM. This determines the minimum position amount of
outside air CFM required when the fan is running at maximum
speed.

Configure the Indoor Fan Max Speed CFM
(Configuration→ECON→IDF.C) either to the supply CFM
determined from the fan performance tables or air balance reports.
If using fan performance tables make corrections for all installed
accessory pressure loss and use measured RPM, power and static

pressure readings to determine the actual Indoor Fan Max Speed
CFM (Configuration→ECON→IDF.C).

ECON MIN

AT MAX

FANSPEED

POSITION

(MINP_MAX)

VENTILATION FOR PEOPLE

MINIMUM

IAQ

DAMPER

POSITION

(AQ. MN)

INCREASING VENTILATION

VENTILATION FOR SOURCES

100

AQ
DIFFERENTIAL
LOW (AQD.L)

700

AQ
DIFFERENTIAL
HIGH (AQD.H)

INSIDE/OUTSIDE CO
DIFFERENTIAL

C09145

Fig. 8 -- Economizer Minimum Position

If the indoor fan is not operating, the economizer will be fully
closed, 0% open.

Ventilation

Mode

If the space temperature falls 0.5F below the Occupied Cool Set
Point (Setpoints→OCSP) the compressor will turn off, the indoor
fan speed will be set to the Vent Mode Fan Speed
(Configuration→UNIT→FS.VM) and the economizer will open
to the position that will supply minimum ventilation air at the
configured Vent Mode Fan Speed

(Configuration→UNIT→FS.VM). Default V ent Mode Fan Speed
(Configuration→UNIT→FS.VM) is 50%. Configuring the Vent

Mode Fan Speed (Configuration→UNIT→FS.VM) lower will
provide additional energy savings in vent mode but may not
supply the required ventilation air to the conditioned space at lower
fan speeds.

Demand Control V

The 48PD units can also be equipped with optional CO

entilation

sensors

2

for additional indoor air quality control. When unit is equipped
with a return duct CO
outside air CO

sensor the Economizer minimum position vs. fan

2

speed curve will be recalculated based on the CO

sensor or return duct CO2sensor and

2

level of the

2

return and/or outside air as shown in Fig. 8. See the Indoor Air

48/50PD

2

19

Quality (IAQ) section of the Economizer Operation section above
for more details on Demand Control Ventilation (DCV).

Economizer Operation for Units Equipped with Return
CO

Sensor Only

2

When the CO

(Inputs→AIR.Q→IAQ) below the AQ Differential Low
(Configuration→AIR.Q→AQD.L) value the MP.25, MP.50,

MP .75 and MP.MX points will be recalculated to new values for
MP .25, MP.50, MP.75 based on the Econ Min IAQ Position
(Configuration→AIR.Q→AQ.MN). The economizer outside air
damper will close and reduce the amount of outside air CFM to the
conditioned space based on the lower IAQ sensor readings and
indoor fan speed. The economizer outside air damper will
continue to close and reduce the amount of outside air CFM to the
conditioned space until the damper reaches user configurable Econ
Min IAQ Position (Configuration→AIR.Q→AQ.MN). This will
happen when the Commanded Fan Speed

(Outputs→FANS→F. S P D ) is at the Supply Fan Maximum Speed
(Configuration→UNIT→FS.MX). When the Commanded Fan

Speed (Outputs→FANS→F. S P D ) is between Supply Fan
Maximum Speed (Configuration→UNIT→FS.MX) and the

48/50PD

Supply Fan Minimum Speed (Configuration→UNIT→FS.MN)
the damper will operate in the shaded area of Figure 8 based on the
IAQ Level (Inputs→AIR.Q→IAQ).

Economizer Operation for Units Equipped with Return
CO

Sensor and outside air CO2Sensor

2

The Economizer will operate similar to Economizer Operation for
Units Equipped with Return Air CO
Level (Inputs→AIR.Q→IAQ) will be determined by actual
outside air CO
value for OAQ.

sensor detects a CO2level or IAQ Level

2

Sensor Only but the IAQ

2

measurements instead of the 400 ppm CO2default

2

Air

Air

Cooling Mode Using Space Temperature Sensor T55,
T56, T58 or T59 and Humidistat (HL38MG029 or
TSTATCCPLH01--B)

Enhanced dehumidifying will be provided when a humidistat
(HL38MG029 or TSTATCCPLH01--B) is connected the PD unit
terminal strip across the R and W2 terminals (since the PD unit
does not support the use of conventional thermostat inputs the W2
terminal is reconfigured for humidity input) and Space Humidity
Switch (Configuration→UNIT→RH.SW) configuration variable
is set to 1 (Normally Open-- no call to dehumidify). Relative
humidity set point is set by adjusting the dial on the HL38MG029
or TSTATCCPLH01 --B device. When the humidistat contacts
close and provide 24VAC to the W2 terminal the PD unit will reset
the Supply Air Control Point (Run Status→COOL→SA.CP) by
one degree F lower than the Supply Air Set Point
(Setpoint→SASP) or the current control point if the Supply Air
Set Point (Setpoint→SASP) has already been modified. After 5
minutes if the humidistat contacts are still closed and 24 VAC is
being supplied to the W2 terminal the PD unit will reset the Supply
Air Control Point (Run Status→COOL→SA.CP) lower by one
more degree F. This reset cycle will continue to lower the supply
air temperature every 5 minutes until the Supply Air Control Point
(Run Status→COOL→SA.CP) is equal to the Supply Air Set
Point (Setpoint→SASP) + SASP Maximum Reset Down
(Configuration→COOL→SAT→SA.MD). The unit will continue
to operate at this reduced supply air temperature control point until
the humidistat contacts open and 24VAC is no longer supplied to
the W2 terminal. When 24VAC is no longer supplied to the W2
terminal the supply air control point will be reset higher by one
degree F. After 3 minutes if the humidistat contacts are still open
and 24VAC is not being supplied to the W2 terminal PD unit will
reset the Supply Air Control Point (Run Status→COOL→SA.CP)
higher by one more degree F. This reset cycle will continue to
raise the Supply Air Control Point (Run Status→COOL→SA.CP)
every 3 minutes until the Supply Air Control Point (Run

Status→COOL→SA.CP) is equal to the Supply Air Set Point
(Setpoint→SASP) or the supply air control point if reset was being

applied due to cooling requirements that reset the Supply Air Set
Point (Setpoint→SASP). Whenever Relative Humidity Reset is
applied the space temperature is controlled by modulating the fan
speed even if the fan was locked at 100% due to (Setpoint→
reset.

SASP)

Cooling Mode Using Space Temperature Sensor T55,
T56, or T58 and Humidity Sensor (HL39ZZ007 or
33ZCSENRH--01)

Enhanced dehumidifying will be provided when a humidly sensor
(HL39ZZ007 or 33ZCSENRH --01) 4 to 20 ma control is
connected the PD unit terminal strip across the TB1 -- J10 pin 3 and
4, power to humidity sensor is connected to R and C, the RH
Sensor on OAQ Input (Configuration→UNIT→RH.S) is set to
YES and Space Humidity Switch
(Configuration→UNIT→RH.SW) configuration variable is set to

0. Relative humidity set point is set by changing the value of
Space RH Set point (Setpoint→RH.SP). When the relative
humidity in the space is above the Space RH Set point
(Setpoint→RH.SP) the PD unit controls will reset the supply air
temperature by one degree F lower than the Supply Air Set Point
(Setpoint→SASP) or the current control point if the Supply Air
Set Point (Setpoint→SASP) has already been modified. After 5
minutes the PD unit will reset the Supply Air Control Point (Run
Status→COOL→SA.CP) lower by one more degree F. This reset
cycle will continue to lower the Supply Air Control Point (Run
Status→COOL→SA.CP) every 5 minutes until the Supply Air
Control Point (Run Status→COOL→SA.CP) is equal to the
Supply Air Set Point (Setpoint→SASP) +SASPMaximumReset
Down (Configuration→COOL→ SAT→SA.MD). When the
relative humidity in the space goes below the Space RH Set Point

(Setpoint→RH.SP) -- the Space RH Deadband
(Setpoint→RH.DB) the supply air control point will be reset

higher by one degree F. After 3 minutes if the humidity sensor
reading is still below the Space RH Set Point (Setpoint→RH.SP) --
the Space RH Deadband (Setpoint→RH.DB), the PD unit will
reset the Supply Air Control Point (Run

Status→COOL
cycle will continue to raise the Supply Air Control Point (Run
Status→COOL→SA.CP) every 3 minutes until the supply air

temperature control point is equal to the Supply Air Set Point
(Setpoint→SASP) or the supply air control point if reset was being
applied due to cooling requirements that reset the Supply Air Set
Point (Setpoint→SASP).

→SA.CP) higher by one more degree F. This reset

Heating Modes

Gas Heating Mode Using Space Temperature Sensor
T55, T56, or T58 (48PD Units Only)

For gas units, the Type of Heat Installed
(Configuration→HEAT→HT.TY) will be factory set to a value of

1.
Heat will not operate if the outdoor temperature is greater than the

value configured for the Heating Lockout Temperature

(Configuration→HEAT→HT.LO), Heat Minimum On Time
(Configuration→HEAT→MRT.H) and Heat Minimum Off Time
(Configuration→HEAT→MOT.H). Timeguards apply to both

stages of heating. Factory defaults values are 2 minute s ON and 2
minutes OFF. The Integrated Gas Controller (IGC) minimum
on--time of 1 minute will be followed even if Heat Minimum On
Time (Configuration→HEAT→MRT.H) is lower and during
Service Test.

If the indoor fan control is configured to cycle with the heating
demand by setting Fan ON When Occupied Heat Minimum On
Time (Configuration→UNIT→OC.FN) to NO, the fan will stop
after a delay configured by Fan--off Delay, Gas Heat
(Configuration→HEAT→FOD.G). The factory default for
Fan--off Delay, Gas Heat (Configuration→HEAT→FOD.G) is 45
seconds. If the IGC temperature limit switch opens within 10
minutes of the end of the gas heat cycle, the next fan off delay will

20

be extended by 15 seconds. The maximum delay is 3 minutes.
Once modified by the IGC, the fan off delay will not change back
to the configured Fan--off Delay, Gas Heat
(Configuration→HEAT→FOD.G) unless power is reset to the
control.

A light emitting diode (LED) is provided on the IGC to indicate
status. During normal operation the LED is continuously on. See
the Troubleshooting section if the LED is off or flashing. The IGC
is located behind the gas section access panel door. See Figure 8 or
9 for location.

The 48/50PD unit control will switch automatically between
cooling and heating to maintain space temperature. To minimize
unnecessary changes there is a 10 minute Mode Select Timeguard
(Operating Modes→HEAT→MS.TG) after the last stage of
cooling turns off and before the heating is allowed.

The unit tries to maintain the space temperature at the Occupied
Heat Setpoint (Setpoint→OHSP) or the Unoccupied Heat Setpoint
(Setpoint→UHSP). See the Occupancy Determination section for
factors that affect the Currently Occupied (Run

Status→VIEW→OCC) parameter. Heating Demand (Operating
Modes→HEAT→SPT→DMD.H) is equal to the occupied or
unoccupied set point minus the Space Temperature (Operating
Modes→HEAT→SPT→SPT) [DMD.H = Setpoint -- SPT].

Two methods are used to add and remove stages of heating for
48PD units. The first method causes the unit to operate around its
steady state number of stages. For example, if the correct number
of stages is between 0 and 1, this method will cause the first stage
to cycle. If the correct number of stages is between 1 and 2, this
method will cause the second stage to cycle. The second method
causes the unit to find the steady--state number of stages. Details of
these methods are provided below.

The control uses two methods to add a stage of heating. The first
method will add a stage of heating when the Heating Demand
(Operating Modes→HEAT→SPT→DMD.H) plus the change in
Spacetemp Trend (Operating Modes→HEAT→SPT→TRND)
times the Heat Thermal Lag Factor (Operating

Modes→HEAT→

SPT→H.LAG) is greater than the SPT Heat

Demand (+) Level (Operating Modes→HEAT→SPT→HT.PD)

[DMD.H + change TRND * H.LAG > HT.PD].
The second method will add a stage of heating when Heat Demand

(Operating Modes→HEAT→SPT→DMD.H) is greater that the
SPT Heat Demand (+) Level (Operating

Modes→HEAT→SPT→HT.PD) plus 0.5 degrees F [DMD.H >
HT.PD + 0.5] and the heat demand is changing at a rate greater

than 0.3 degrees F per minute.

The control uses two methods to remove a stage of heating. The
first method will remove a stage of heating when the Heating
Demand (Operating Modes→HEAT→SPT→DMD.H) plus the
change in Spacetemp Trend (Operating
Modes→HEAT→SPT→TRND) times the Heat Thermal Lag
Factor (Operating Modes→HEAT→SPT→H.LAG)islessthan
the SPT Heat Demand (--) Level (Operating

Modes→HEAT→SPT→HT.ND) [DMD.H + change TRND *
H.LAG < HT.ND].

The second method will remove a stage of heating when Heat
Demand (Operating Modes→HEAT→

SPT→DMD.H) is less that

the SPT Heat Demand (--) Level (Operating

Modes→HEAT→SPT→HT.ND) minus 0.5 degrees F [DMD.H <
HT.PD -- 0.5] and the heat demand is changing at a rate greater

than 0.3 degrees F per minute.
Configurable delays also apply when adding stages per Heat Stage

Increase Time (Configuration→HEAT→H.INC) or removing
stages per Heat Stage Decrease Time

(Configuration→HEAT→H.DEC). Heat Minimum On Time
(Configuration→HEAT→MRT.H) and Heat Minimum Off Time
(Configuration→HEAT→MOT.H) also apply.

Supply--Air Temperature Sensor (SA

T)

The SAT Heat Mode Sensing
(Configuration→HEAT→SAT→SAT.H) affects the Supply Air
Temperature (Temperatures→AIR.T→SAT) value displayed. This
configuration is accessible via the Scrolling Marquee on the SAT
Heat Mode Sensing (Configuration→HEAT→SAT→SAT.H).

When the SAT Heat Mode Sensing
(Configuration→HEAT→SAT→SAT.H) =DSBL, the Supply Air
Temperature (T emperatures→AIR.T→SAT) value on the
Scrolling Marquee and the CCN tables will be forced to zero when
heat outputs come ON and for 5 minutes after. The default Supply
Air Temperature (Temperatures→AIR.T→SAT) location is at the
fan inlet, upstream of the heat section.

When the SAT Heat Mode Sensing
(Configuration→HEAT→SAT→SAT.H) =ENBL, the Supply Air
Temperature (Temperatures→AIR.T→SAT) sensor reading is
displayed at the Scrolling Marquee and the CCN tables during
heating mode. This setting should only be used if the original SAT
sensor wires are removed from the Main Base Board (MBB) and
replaced by an accessory SAT sensor located in the supply duct
downstream of the heat section. There are then two supply air
temperature limits that become active, the Maximum SAT Lower
Level (Configuration→HEAT→SAT→SAM.L) the Maximum
SAT Upper Level (Configuration→HEAT→SAT→SAM.U).
Any time the supply air temperature rises above the Maximum
SAT Lower Level (Configuration→HEAT→SAT

→SAM.L) the

heat staging will be limited to what is currently on and no
additional stages can be added until the supply air temperature falls
below the Maximum SAT Lower Level
(Configuration→HEAT→SAT→SAM.L). If the supply air
temperature rises above the Maximum SAT Upper Level
(Configuration→HEAT→SAT→SAM.U), then heating will be
reduced by removing a heat stage. That stage can not be added
again until the Supply Air Temperature
(Temperatures→AIR.T→SAT) falls below the Maximum SAT
Lower Level (Configuration→HEAT→SAT→SAM.L).Ifthe
supply air temperature stays above the Maximum SAT Upper
Level (Configuration→HEAT→SAT→SAM.U), then another
stage will be removed after the Heat Stage Decrease Time
(Configuration→HEAT→H.DEC).

In heating mode the PD control will maintain the Occupied Heat
Set Point (Setpoint→OHSP) or the Unoccupied Heat Set Point
(Setpoint→UHSP) by turning on or off the Stage 1 and Stage 2
Gas Heat at the Supply Fan Minimum Speed
(Configuration→UNIT→FS.MN).

When the space temperature sensor detects the space temperature
below the Occupied Heat Set Point (Setpoint→OHSP) or
Unoccupied Heat Set Point (Setpoint→UHSP) and power is sent
to the Integrated Gas Unit Controller (IGC) board. The heat
staging is determined as described above and the Integrated Gas
Controller (IGC) initiates the gas heat module start-- up.

Gas Heat

Start--Up

An LED (light-emitting diode) on the IGC board will be on during
normal operation. A check is made to ensure that the rollout switch
and limit switch are closed and the induced--draft motor is running.
The induced-draft motor is then energized, and when speed is
proven with the Hall Effect sensor on the motor, the ignition
activation period begins. The burners will ignite within 5 seconds.
If the burners do not light, there is a 22-second delay before
another 5-second attempt. If the burners still do not light, this
sequence is repeated for 15 minutes. After the 15 minutes have
elapsed, if the burners still have not lit, heating is locked out.
When ignition occurs the IGC board will continue to monitor the
condition of the rollout and limit switches, the Hall Effect sensor,
as well as the flame sensor. If for some reason the over temperature
limit opens prior to the start of the indoor fan blower, on the next
attempt, the 45-second delay will be shortened to 5 seconds less
than the time from initiation of heat to when the limit tripped. Gas

48/50PD

21

will not be interrupted to the burners and heating will continue.
Once modified, the fan on delay will not change back to 45
seconds unless power is reset to the control. When the indoor fan
turns on after the 40 or 45 second delay the indoor fan will run at
100% fan speed.

Gas Heat

When additional heat is required, power is supplied to the second
stage of the main gas valve. When the space temperature is 0.5F
above the Occupied Heat Set Point (Setpoint→OHSP) or
Unoccupied Heat Set Point (Setpoint→UHSP) power is removed
from the second stage of the main gas valve and to the IGC W1
terminal. Both stage 1 and stage 2 of the gas valve closes,
interrupting the flow of gas to the main burners.

Gas Heat Shut

If power to the IGC W1 terminal lasted less than 1 minute, the
heating cycle will not terminate until 1 minute after power is
applied to the W1 terminal of the IGC board. If the over
temperature limit opens after the indoor motor is stopped within 10
minutes of W1 becoming inactive, on the next cycle the time will
be extended by 15 seconds. The maximum delay is 3 minutes.

48/50PD

Once modified, the fan off delay will not change back to 45
seconds unless power is reset to the control. A LED indicator is
provided on the IGC to monitor operation. The IGC is located in
the gas burner section and can be accessed by opening the gas
access door. During normal operation, the LED is continuously
on.

Gas Heat with

When there is a call for heat as described above the indoor fan will
operate at the Supply Fan Maximum Speed
(Configuration→UNIT→FS.MX) configuration setting and the
economizer outdoor air damper will move to the Econ Min at Max
Fan Speed (Configuration→ECON→MP.MX) position. The
economizer outdoor air damper is closed when the indoor fan is
not operating.

Staging

Down

Economizer

Electric Heating Mode Using Space Temperature
Sensor T55, T56, or T58 (50PD Units Only)

For electric heat units with factory installed electric heat, the Type
of Heat Installed (Configuration→HEAT→HT.TY) will be
factory set to a value of 2 and the Number of Heat Stages
(Configuration→HEAT→N.HTR) will be factory set to match the
installed heater. If electric heat is installed in the field the value for
Number of Heat Stages (Configuration→HEAT→N.HTR) must
be changed to match the number of heat stages installed.

Heat will not operate if the outdoor temperature is greater that the
value configured for the Heating Lockout Temperature

(Configuration→HEAT→HT.LO), Heat Minimum On Time
(Configuration→HEAT→MRT.H) and Heat Minimum Off Time
(Configuration→HEAT→MOT.H). Timeguards apply to both

stages of heating. Factory defaults values are 2 minute s ON and 2
minutes OFF.

If the indoor fan control is configured to cycle with the heating
demand by setting Fan ON When Occupied Heat Minimum On
Time (Configuration→UNIT→OC.FN) to NO, the fan will stop
after a delay configured by Fan--off Delay, Elect Heat
(Configuration→HEAT→FOD.E). The factory default for
Fan--off Delay, Elect Heat (Configuration→HEAT→FOD.E) is
30 seconds.

The electronic control uses information from the space sensor to
determine the number of heat stages required. Once the number of
stages needed for heating is determined, either Heat Stage 1 Relay

(Outputs→HEAT→HT.1), or Heat Stage 1 Relay
(Outputs→HEAT→HT.1) and Heat Stage 2 Relay
(Outputs→HEAT→HT.2) outputs will be turned on. See Gas

Heating Mode Using Space Temperature Sensor for more
information.

Supply--Air Temperature Sensor (SA

The SAT Heat Mode Sensing
(Configuration→HEAT→SAT→SAT.H) affects the Supply Air
Temperature (Temperatures→AIR.T→SAT) value displayed. This
configuration is accessible via the Scrolling Marquee on the SAT
Heat Mode Sensing (Configuration→HEAT→SAT→SAT.H).

When the SAT Heat Mode Sensing
(Configuration→HEAT→SAT→SAT.H) =DSBL, the Supply Air
Temperature (T emperatures→AIR.T→SAT) value on the
Scrolling Marquee and the CCN tables will be forced to zero when
heat outputs come ON and for 5 minutes after. The default Supply
Air Temperature (Temperatures→AIR.T→SAT) location is at the
fan inlet, upstream of the heat section.

When the SAT Heat Mode Sensing
(Configuration→HEAT→SAT→SAT.H) = ENBL, the Supply
Air Temperature (Temperatures→AIR.T→SAT) sensor reading is
displayed at the Scrolling Marquee and the CCN tables during
heating mode. This setting should only be used if the original SAT
sensor wires are removed from the Main Base Board (MBB) and
replaced by an accessory SAT sensor located in the supply duct
downstream of the heat section. There are then two supply air
temperature limits that become active, the Maximum SAT Lower
Level (Configuration→HEAT→SAT→SAM.L) the Maximum
SAT Upper Level (Configuration→HEAT→SAT→SAM.U).
Any time the supply air temperature rises above the Maximum
SAT Lower Level (Configuration→HEAT→SAT
heat staging will be limited to what is currently on and no
additional stages can be added until the supply air temperature falls
below the Maximum SAT Lower Level
(Configuration→HEAT→SAT→SAM.L). If the supply air
temperature rises above the Maximum SAT Upper Level
(Configuration→HEAT→SAT→SAM.U), then heating will be
reduced by removing a heat stage. That stage can not be added
again until the Supply Air Temperature
(Temperatures→AIR.T→SAT) falls below the Maximum SAT
Lower Level (Configuration→HEAT→SAT→SAM.L).Ifthe
supply air temperature stays above the Maximum SAT Upper
Level (Configuration→HEAT→SAT→SAM.U), then another
stage will be removed after the Heat Stage Decrease Time
(Configuration→HEAT→H.DEC).

Temperature Compensated Start

This logic is used when the unit is in the unoccupied state. The
control will calculate early Start Bias time based on Space
Temperature deviation from the occupied cooling and heating set
points. This will allow the control to start the unit so that the space
is at conditioned levels when the occupied period starts. This is
required for ASHRAE 90.1 compliance.

Setting Up the System

The settings for temperature compensated start can be found in the
local display under Configuration→UNIT.

ITEM EXPANSION RANGE UNITS CCN POINT

TCS.C

TCS.H

Temp Comp Strt Cool Factr (TCS.C)

This is the factor for the start time bias equation for cooling.

Temp Comp Strt Heat Factr (TCS.H)

This is the factor for the start time bias equation for heating.

IMPORTANT: Temperature compensated start is disabled when
these factors are set to 0.

Temp.Cmp.Strt.Cool Factr 0 --- 6 0 min TCSTCOOL

Temp.Cmp.Strt.Heat Factr 0 --- 6 0 min TCSTHEAT

T)

→SAM.L) the

22

Temperature Compensated Start Logic

The following conditions must be met for the algorithm to run:

S Unit is in unoccupied state.
S Next occupied time is valid.
S Current time of day is valid.
S Valid space temperature reading is available (sensor or CCN

network).

The algorithm will calculate a Start Bias time in minutes using the
following equations:

If (space temperature > occupied cooling set point)

Start Bias Time = (space temperature -- occupied cooling set
point)*TCS.C

If (space temperature < occupied heating set point)

Start Bias Time = (occupied heating set point -- space
temperature)*TCS.H

When the Start Bias Time is greater than zero the algorithm will
subtract it from the next occupied time to calculate the new start
time. When the new start time is reached, the Temperature
Compensated Start mode is set, the fan is started and the unit
controlled as in an occupied state. Once set, Temperature
Compensated mode will stay on until the unit goes into the
Occupied mode. The Start Bias Time will be written into the CCN
Linkage Equipment Table if the unit is controlled in DAV mode. If
the Unoccupied Economizer Free Cool mode is active when
temperature compensated start begins, the Unoccupied Free Cool
mode will be stopped.

IMPORTANT: The maximum minutes Start Bias can be is 180.

Carrier Comfort Network (CCN)R
Configuration

It is possible to configure the ComfortLink™ control to participate
as an element of the Carrier Comfort Network (CCN) system
directly from the local display. This section will deal with
explaining the various programmable options which are found
under the CCN sub-menu in the Configuration mode.

The major configurations for CCN programming are located in the
local displays at Configuration→CCN. See Appendix A.

CCN Address (CCN.A)

This configuration is the CCN address the rooftop is assigned.

CCN Address (CCN.B)

This configuration is the CCN bus the rooftop is assigned.

CCN Baud Rate (BAUD)

This configuration is the CCN baud rate.

CCN Time/Date Broadcast (BROD→B.TIM)

If this configuration is set to ON, the control will periodically send
the time and date out onto the CCN bus once a minute. If this
device is on a CCN network then it will be important to make sure
that only one device on the bus has this configuration set to ON. If
more than one time broadcaster is present, problems with the time
will occur.

IMPORTANT: Only the time and date broadcaster can perform

daylight savings time adjustments. Even if the rooftop is stand
alone, the user may want to set this to ON to accomplish the
daylight/savings function.

CCN OAT Broadcast (BROD→B.OAT)

If this configuration is set to ON, the control will periodically
broadcast its outside-air temperature at a rate of once every 30
minutes.

Global Schedule Broadcast (BROD→B.GS)

If this configuration is set to ON and the schedule number
(SCH.N) is between 65 and 99, then the control will broadcast the
internal time schedule once every 2 minutes.

CCN Broadcast Acknowledger (BROD→B.ACK)

If this configuration is set to ON, then when any broadcasting is
done on the bus, this device will respond to and acknowledge.
Only one device per bus can be configured for this option.

Schedule Number (SCH.O→SCH.N)

This configuration determines what schedule the control may
follow.

SCH.N = 0 The control is always occupied.

SCH.N = 1 The control follows its internal time

schedules. The user may enter any
number between 1 and 64 but it will
be overwritten to “1” by the control
as it only has one internal schedule.

SCH.N = 65--99 The control is either set up to

receive to a broadcasted time

schedule set to this number or the

control is set up to broadcast its

internal time schedule (B.GS)tothe

network and this is the global

schedule number it is broadcasting.

If this is the case, then the control

still follows its internal time

schedules.

Accept Global Holidays? (SCH.O→HOL.G)

If a device is broadcasting the time on the bus, it is possible to
accept the time yet not accept the global holiday from the broadcast
message.

Override Time Limit (SCH.O→OV.TL)

This configuration allows the user to decide how long an override
occurs when it is initiated. The override may be configured from 1
to 4 hours. If the time is set to 0, the override function will
become disabled.

Timed Override Hours (SCH.O→OV.EX)

This displays the current number of hours left in an override. It is
possible to cancel an override in progress by writing “0” to this
variable, thereby removing the override time left.

SPT Override Enabled? (SCH.O→OV.SP)

If a space sensor is present, then it is possible to override an
unoccupied period by pushing the override button on the T55 or
T56 sensor. This option allows the user to disable this function by
setting this configuration to NO.

Demand Limit

Demand Limit Control may override the cooling algorithm to limit
or reduce cooling capacity during run time. The term Demand
Limit Control refers to the restriction of machine capacity to
control the amount of power that a machine will use. This can save
the owner money by limiting peaks in the power supply. Demand
limit control is intended to interface with an external network
system. This is through a CCN Loadshed POC Device or writing
to network points.

To limit stages through network writes, the points Run Status
→COOL→MAX.C and Run Status→HEAT→MAX.H are forced
on the network through CCN points MAX_CAPC and
MAXHSTGS respectively. Force these to the desired maximum
cooling/dehumidification capacity and the maximum heating
stages, respectively. When there is no force on these points, they
automatically reset to allow full cooling/dehumidification capacity
and all heating stages to be used. These points are reset at
power-- on/reset (POR).

When using the Loadshed POC to do Demand Limiting, the cool
capacity and heat stage limits under both Redline and Loadshed
conditions can be set individually with configuration decisions. If
the active stages are greater then the loadshed or redline
configurations when a loadshed or redline command is given, the
unit will reduce capacity or remove stages. The configuration
points can be found in Configuration→CCN→LDS.

23

48/50PD

Loadshed Group Number (S.GRP)

This corresponds to the loadshed supervisory devices that reside
elsewhere on the CCN network and broadcast loadshed and redline
commands to its associated equipment parts. This variable will
default to zero which is an invalid group number. This allows the
loadshed function to be disabled until configured.

Redline Max Capacity (R.MXC)

This configuration tells the unit the maximum
cooling/dehumidification capacity allowed active during a
loadshed condition.

Redline Max Heat Stages (R.MXH)

This configuration tells the unit the maximum heating stages
allowed to be on during a redline condition.

Loadshed Max Heat Stages (R.MXH

This configuration tells the unit the maximum heating stages
allowed to be on during a loadshed condition.

The two Demand Limiting methods can be active simultaneously.
The lowest cool capacity and heat stage limits imposed by either
method are applied, and these “effective limits” are shown in the

48/50PD

points CAPLIMIT (Run Status→COOL→LMT.C)and
HSTGLIMT (Run Status→HEAT→LMT.H), respectively. In
normal running mode, these limits will prevent capacity/stages
from being added, or capacity/stages to be removed, as applicable.
In test mode, these limits are ignored, and the user may continue to
operate at full load.

The point MODEDMDL (Run Status→MODE→D.LMT)isused
to show if any Demand Limiting is in effect that prevents the unit
from operating either cooling or heating at full--capacity.

IMPORTANT: MODEDMDL may reflect that staging is NOT
limited even though Loadshed is active or the network points are
being forced, if the capacity/stage limits in effect are not less than
the capacity/stages present in the unit.

If a more drastic mode of Demand Limiting is required, the
network point HVACDOWN (Run Status→MODE→HV.DN) can
be used to prohibit the unit from selecting any HVAC mode, thus
preventing the operation of the supply fan, compressors, condenser
fans, and heat stages. This point must also be forced, and is reset
automatically when not forced, and at POR.

Alarm Handlin g

There are a variety of different alerts and alarms in the system.
Alerts are indicated by TXXX (where XXX is the alert number) on
the display and generally signify that the improperly functioning
circuit can restart without human interaction. If an alarm occurs,
indicated by AXXX (where XXX is the alarm numb er), the
damaged circuit will generally not restart without an alarm reset via
the Scrolling Marquee display or CCN.

The response of the control system to various alerts and alarms
depends on the seriousness of the particular alert or alarm. In the
mildest case, an alert does not affect the operation of the unit in any
manner. An alert can also cause a “strike.” A “striking” alert will
cause the circuit to shut down for 15 minutes. This feature reduces
the likelihood of false alarms causing a properly working system to
be shut down incorrectly. If three strikes occur before the circuit
has an opportunity to show that it can function properly, the circuit
will strike out, causing the shutdown alarm for that particular
circuit. Once activated, the shutdown alarm can only be cleared via
an alarm reset.

However, circuits with strikes will be given an opportunity to reset
their strike counter to zero. As discussed above, a strike typically
causes the circuit to shut down. Fifteen minutes later, that circuit
will once again be allowed to run. If the circuit is able to run for 1
minute, its replacement circuit will be allowed to shut down (if not
required to run to satisfy requested stages). However, the
“troubled” circuit must run continuously for a user defined time
(Configuration→COOL→RST.C) with no detectable problems

before the strike counter will be reset to zero. Default value is 5
minutes.

CCN Alarm Broadcast

Operators of CCN networks might not want to be notified of
“striking” alerts for refrigerant circuits until the circuit has been
shut down due to 3 strikes. Set the cooling configuration of Alert
Each Strike (Configuration→COOL→ALM.N on display,
ALM_NOW on CCN) to YES to broadcast each circuit strike alert.
Set Alert Each Strike to NO to broadcast only circuit shut down.
Alert Each Strike configuration is ignored during Service Test and
all alerts are broadcast.

Alarm Relay Output

The alarm relay output is a normally open 24 vac output between
field connection terminal board terminals C and X. Selection of
which alerts and alarms will result in closing of the alarm relay
may be set in the Alarm Relay Configuration
(Configuration→ALM.O). Setting a configuration to YES will
result in the alarm output relay, ALRM, status of ON and 24 vac
between C and X when that particular condition is in an alarm
state. Setting a configuration to NO will result in no action by the
alarm output relay for that particular condition.

IMPORTANT: An accessory filter switch can be used along with
the alarm relay output function to indicate dirty filter service need.

See the Troubleshooting section for more information on viewing,
diagnosing, and clearing alerts and alarms.

TROUBLESHOOTING

The Scrolling Marquee display shows the actual operating
conditions of the unit while it is running. If there are alarms or
there have been alarms, they will be displayed in either the current
alarm list or the history alarm list. (See Table 8.) The Service Test
mode allows proper operation of the compressors, fans, and other
components to be checked while the unit is not operating. See
Service Test.

Complete Unit Stoppage

There are several conditions that can cause the unit not to provide
heating or cooling:

S If an alarm is active which causes the unit to shut down,

diagnose the problem using the information provided in Alarms

and Alerts section below.

S Cooling and heating loads are satisfied.
S Programmed occupancy schedule.
S General power failure.
S Tripped CB1 or CB2 (24-volt transformer circuit breakers).
S Unit is turned off through the CCN network.
S If outdoor-air temperature is less than the Compressor Lockout

Temperature (CA.LO) configuration value, unit cannot cool.

S If outdoor-air temperature is greater than the Heating Lockout

Temperature (HT.LO) configuration value, unit cannot heat.

Restart Procedure

Before attempting to restart the machine, check the alarm list to
determine the cause of the shut down. If the shutdown alarm for a
particular control function has occurred, determine and correct the
cause before allowing the unit to run under its own control again.
When there is problem, the unit should be diagnosed in Service
Test mode. The alarms must be reset before the control function
can operate in either Normal mode or Service Test mode.

Control Module Communication

Red LED

Proper operation of the MBB, ECB and AUX1 control boards can
be visually checked by looking at the red status LEDs. When
operating correctly, the red status LEDs should blink in unison at a
rate of once every 2 seconds. If the red LED on the ECB and

24

AUX1 is not blinking, check the DIP switch positions on the
board. If the red LEDs are not blinking in unison, verify that
correct power is being supplied to all modules. A blinking red
LED at the rate of once per second means that software is not
loaded on the board. Also, be sure that the board is supplied with
the current software. If necessary, reload current software. A board
LED that is lit continuously should be replaced.

Green LED

The MBB, ECB and AUX1 each have one green LED. The Local
Equipment Network (LEN) LED should always be blinking
whenever power is on. If LEN LED is not blinking, check LEN
connections for potential communication errors (MBB J3, J4, and
J5). Communication between modules is accomplished by a 3-wire
sensor bus. These 3 wires run in parallel from module to module.
The J4 connector on the MBB also provides both power and
communication directly to the Scrolling Marquee display. The J5

Table 7 — LEN and CCN Communication Resistances

connector on the MBB provides a LEN interface at the field
connection terminal (TB).

Yellow LED

The MBB has one yellow LED which is used to indicate CCN
communication activity. The Carrier Comfort Network® (CCN)
LED will blink during times of network communication.

Communication Failures

If the Scrolling Marquee or Navigator display Communication
Failure or the green or yellow LED’s do not flash on the boards
then the problem could be the communication chip on one of the
control boards (MBB, ECB or AUX1). Use an ohm meter to
measure the resistance on the communication pins of the boards to
determine if the board is bad. If the reading is less than half the
value indicated in Table 7, then the board needs to be replaced.

Device

MBB

ECB

AUX1 ---

Board Serial

Number

Prior to 4702N

Starting 4702N

Prior to 0803N

Starting 0803N

(LEN) Resistance between Pins/

Pins 1 to 3 Pins 1 to 2 Pins 2 to 3 Pins 5 to 7 Pins 5 to 6 Pins 6 to 7

15K Ω

J3, J4, & J5

18.9K Ω

J3, J4, & J5

5.9K Ω
J2

18.9K Ω
J2

29K Ω

J9

Connector

7.5K Ω

J3, J4, & J5

9.9K Ω

J3, J4, & J5

5.2K Ω
J2

9.9K Ω
J2

16K Ω

J9

7.5K Ω

J3, J4, & J5

9.9K Ω

J3, J4, & J5

5K Ω

J2

9.9K Ω
J2

13.5K Ω
J9

(CCN) Resistance between Pins/

15K Ω

J5

18.9K Ω
J5

--- --- ---

--- --- ---

--- --- ---

IMPORTANT: The resistive values should be read when the board is powered off and the unit is locked out.

Alarms and Alerts

Viewing and Clearing Unit Alarms

Presence of active alarms will be indicated on the Scrolling
Marquee display by the Alarm Status light turning on and by the
number of active alarms being displayed in the automatic View of
Run Status. Presence of active alarms may also be signaled on the
Alarm Output terminals. Each alarm may also be broadcast on the
CCN network. Active alarms and past alarm history can be
reviewed and cleared via the local display or a CCN device. The
following menu locations are used for the local display:

Alarms→R.CURR (Reset All Current Alarms)

Change to YES to reset all active alarms. Turning unit power off
will also reset all current alarms.

Alarms→R.HIST (Reset Alarm History)

Change to YES to reset the alarm history. Turning unit power off
will not reset the alarm history.

Alarms→CURR (Currently Active Alarms)

Use the ENTER key, then scroll through any alarm numbers using
the up and down arrow keys. Alarms are displayed in numerical
order.

Alarms→HIST (Alarm History)

Use the ENTER key, then scroll through any alarm numbers using
the up and down arrow keys. Up to 20 alarms are displayed in
order of occurrence, with time and date.

The description for an alarm can be viewed on the Scrolling
Marquee display by pressing ESCAPE and ENTER keys
simultaneously while displaying the alarm code number. Be sure to
expand description for each code, because in some cases there are
different possible descriptions and causes for the same code
number.

Diagnostic Alarm Codes and Possible Causes

Alert Code T051

There are 5 different texts for this alert code. There are three
different alerts, two of which have corresponding test mode alerts
indicated with “Service Test” in the expanded text. Pressing enter
and esc on the marquee or navigator to expand the T051 alert will
show you one of the below alerts. Make sure the expanded text is
read correctly before troubleshooting.

S Digital Compressor Control Board Alarm

This alert occurs when the Digital Scroll Controller (DSC)

energizes its alarm relay. Refer to the DSC’s LED diagnostic to

determine which of the nine codes are present. Power cycle will

clear the DSC’s LED code. When the DSC’s alarm clears, this

alert will automatically clear.

S Compressor A1 Safety Trip

This Alert indicates that Current Sensing A1 (CS.A1) has been

enabled. The unit does not support the use of a current sensor at

this time. Change the CS.A1 to disable and this alert will clear

and not return.

(Configuration→COOL→CS.A1)

S Compressor A1 Current Detected After Turnoff

This Alert indicates that Current Sensing A1 (CS.A1) has been

enabled. The unit does not support the use of a current sensor at

this time. Change the CS.A1 to disable and this alert will clear

and not return.

(Configuration→COOL→CS.A1)

Alert Code T064 -- Circuit A Saturated Condensing
Temperature Thermistor Failure

This alert occurs when the temperature is outside the range -- 40_ to
240_F(--40_ to 116_C). When this occurs, the control will use

Connector

7.5K Ω
J5

9.9K Ω
J5

7.5K Ω
J5

9.9K Ω
J5

48/50PD

25

only the outdoor temperature to control the outdoor fans. If both
the SCT and OAT fail, then circuit shutdown alarm will occur also.
The cause of the alert is usually a faulty thermistor, a shorted or
open thermistor caused by a wiring error, or a loose connection.

Alert Code T066 -- Circuit A Saturated Suction Temperature
Thermistor Failure

This alert occurs when the unit’s suction transducers are turned off
internally. Cooling will not operate. This is usually due to a
network force on a non exposed CCN point. Reload factory
defaults or reinstall software o n the MBB. Consult the network
manager if alert continues.

Alert Code T073 -- Outdoor Air Temperature Thermistor
Failure

This alert occurs when the temperature is outside the range -- 40_ to
240_F(--40_ to 116_C). For all units, all ambient temperature
lockout limits for cooling and heating are ignored. For all units, if
both SCT and OAT fail, then circuit shutdown alarm will also
occur. For economizer equipped units, the economizer will not
operate to provide cooling. The economizer will still operate for
ventilation. The control will use condenser temperatures for
outdoor fan control. For units with CCH crankcase heat relay

48/50PD

control, the crankcase heat relay will be turned on if any
compressor is off. This alert resets automatically. The cause of the
alert is usually a faulty thermistor, a shorted or open thermistor
caused by a wiring error, or a loose connection.

Alert Code T074 -- Space Temperature Thermistor Failure

This alert occurs when the temperature is outside the range -- 40_ to
240_F(--40_ to 116_C). Cooling and heating will not operate. For
economizer equipped units, the economizer will still operate for
ventilation. This alert resets automatically. The cause of the alert is
usually a faulty thermistor in the T--55, T--56, or T--58 device, a
shorted or open thermistor caused by a wiring error, or a loose
connection.

Alert Code T075 -- Supply Air Temperature Thermistor
Failure

This alert occurs when the temperature is outside the range -- 40_ to
240_F(--40_ to 116_C). Economizer cooling and compressor
operation cannot occur while this alert is active. The unit will not
be allowed to enter cooling mode. This alert resets automatically.
The cause of the alert is usually a faulty thermistor, a shorted or
open thermistor caused by a wiring error, or a loose connection.

Alert Code T076 -- Return Air Thermistor Failure

This alert occurs when the temperature is outside the range -- 40_ to
240_F(--40_ to 116_C). Differential dry bulb crossover control
can not occur. Free cooling can only be controlled by the OAT and
enthalpy. This alert resets automatically. The cause of the alert is
usually a faulty thermistor, a shorted or open thermistor caused by
a wiring error, or a loose connection.

Alert Code T077 -- Space Relative Humidity Sensor Failure

This alert occurs when the input is less than 3.5 mA and the sensor
is configured as installed. If a humidistat is not installed, then
dehumidification will not be functional. Check sensor and wiring.
This alert clears automatically.

IMPORTANT: An ECB must be installed to use the space
relative humidity sensor.

Alert Code T092 -- Circuit A Suction Pressure Transducer
Failure

This alert occurs when the board does not properly read the
transducer voltage. A circuit cannot run when this alert is active.
Use the Scrolling Marquee to reset the alarm. The cause of the alert
is usually a faulty transducer, faulty 5 -- v power supply, or a loose
connection.

Alert Code T102 -- Compressor A1 Current Sensor Failure

This Alert indicates that Current Sensing A1 (CS.A1) has been
enabled. The unit does not support the use of a current sensor at

this time. Change the CS.A1 to disable and this alert will clear and
not return.
(Configuration→COOL→CS.A1)

Alert Code T110 -- Circuit A Lo ss of Charge

This alert has “Service Test” text that will be displayed if the alert
occurred during service test. This alert occurs when the
compressor is OFF and the suction pressure is less than 5 psig and
OAT is greater than -- 5_F for 1 continuous minute. Use the
Scrolling Marquee to reset the alert. The cause of the alert is
usually low refrigerant pressure or a faulty suction pressure. This
alert only occurs when the compressor is OFF because the low
refrigerant pressure alarms (alert T133) handle this situation when
the compressor is operating.

Alert Code T126 -- Circuit A High Discharge Pressure

This alert has “Service Test” text that will be displayed if the alert
occurred during service test. This alert occurs when alert T051 is
active while the appropriate condensing temperature is greater than
150_F. This alert reset automatically. The cause of the alert is
usually an overcharged system, high outdoor ambient temperature
coupled with dirty outdoor coil, plugged filter drier, or a faulty
high--pressure switch. See Alert T051 for diagnostic procedure.

Alert Code T133 -- Circuit A Low Refrigerant Pressure

This alert has “Service Test” text that will be displayed if the alert
occurred during service test. This alert occurs when the
compressor is operating and the evaporating temperature
(converted from the suction pressure) is less than configured low
suction control levels, Configuration→COOL→SST→SST.1
(Low Suction - Level 1) or SST.2 (Low Suction - Level 2) or
SST.3 (Low Suction Level 3). The circuit SST value must be less
than SST.1 (for 5 minutes), SST.2 (for 4 minutes), or SST.3 (for 3
minutes when using the economizer and 1.5 minutes when not
using the economizer) for the alert to occur. When the outdoor
temperature is less than 40_F, the above values are reduced 1_Ffor
every 2_F the OAT is below 40_F. An alert will also occur if the
circuit SST value is less than SST.3 --5_F for 20 seconds and the
outdoor temperature is above 40_F. All the above timers will reset
if the suction temperature rises above SST.O for 1 minute. This
alert causes a strike for the respective circuit. This alert will activate
when the coil becomes frosted. However, during the 15--minute
reset period, the coils will thaw and strike should clear and restart if
there is nothing else wrong with the circuit. The alert resets
automatically. The cause of the alert is usually low refrigerant
charge, dirty filters, evaporator fan operating backwards, loose or
broken belt, plugged filter drier, faulty transducer, excessively cold
return air, or stuck open economizer when the ambient temperature
is low.

Alert Code T143 -- Circuit A Failure to Pressurize

This alert has “Service Test” text that will be displayed if the alert
occurred during service test. This alert occurs when the
compressor turns on and the difference between suction and
discharge pressure is less then the Ckt A Minimum Pressure
(Configuration→COOL→SST→PSI.D). The pressure difference
must be greater then PSI.D (default is 20 psi) after 60 seconds and
stay above it while running the compressor. This alert causes a
strike for the respective circuit. The alert resets automatically. The
cause of the alert is usually compressor wiring causing reverse
rotation or a faulty compressor.

Alert Code T153 -- Real Time Clock Hardware Failure

This alert occurs when the RTC clock chip on the MBB is not
responding. Time and date functions will not operate, such as local
occupancy schedules. The unit will default to 24/7 unoccupied
mode. Recovery is automatic but MBB board replacement may be
necessary. Cycling power to the control and reconfiguring the time
and date should be tried before board replacement.

Alarm Code A154 -- Serial EEPROM Hardware Failure

The unit will completely shut down. The serial EEPROM chip on
the MBB, which stores the unit’s configuration, is not responding.

26

Recovery is automatic but MBB board replacement may be
necessary. Cycling the power to the control should be tried before
board replacement.

Alarm Code T155 -- Serial EEPROM Storage Failure Error

Configuration data in the serial EEPROM chip can not be verified.
The unit will run to last know good values or defaults, and
therefore operating errors may occur. Recovery is automatic but
MBB board replacement may be necessary. Cycling power to the
control and reconfiguring the control points should be tried before
board replacement.

Alarm Code A156 -- Critical Serial EEPROM Storage Fail
Error

The unit will completely shut down. Critical configuration data in
the serial EEPROM chip can not be verified. Recovery is automatic
but MBB board replacement may be necessary. Cycling power to
the control and reconfiguring the critical control points should be
tried before board replacement. There are no critical configurations
in the 48/50PD.

Alert Code A157 -- A/D Hardware Failure

The unit will completely shut down. The analog to digital
conversion chip on the MBB has failed. Recovery is automatic but
MBB board replacement may be necessary. Cycling power to the
control should be tried before board replacement.

Alert Code A163 -- Circuit A Down due to Failure

This alarm occurs when a circuit has 3 strikes. Use the Scrolling
Marquee display to reset the alarm. Investigate the alarm that
caused the strikes to occur.

Alert Code T178 -- Loss of Communication with the Capacity
Control Board

This alert occurs when the MBB cannot communicate with the
AUX1 board. Unit operation will b e disabled. This is usually
caused by a wiring problem. Investigate using the Low Voltage
Schematic, check that the AUX1 address is correct, and verify the
resistance between pins on the LEN connections.

Alert Code T179 -- Loss of Communication with the
Economizer Control Board

This alert occurs when the MBB cannot communicate with the
ECB. Economizer operation will be disabled. This is usually
caused by a wiring problem. If a relative humidity sensor is
installed and configured but there is not an ECB installed on the
unit, this alert will be generated (the ECB is required for RH sensor
operation). Investigate using the Low Voltage Schematic, check
that the ECB address is correct, and verify the resistance between
pins on the LEN connections.

Alert Code T180 -- Loss of Communication with the
Economizer Actuator

This alert occurs when the ECB cannot communicate with the
Belimo Actuator. If the analog signal is connected properly, the
economizer will still be controlled through it. This is usually
caused by a wiring problem, actuator failure, or the wrong actuator.
Investigate using the Low Voltage Schematic, make sure the
actuator is a MFT communication actuator, and verify the feedback
signal from the actuator is correct.

Alarm Code A200 -- Linkage Timeout -- Comm Failure

This alarm occurs when the MBB fails to communicate with a
Linkage device. This only occurs when the MBB has previously
communicated with a Linkage device since last power cycle. If a
back up sensor was not installed the T074 alert will occur shortly
after this one. Reset power to the unit and verify Linkage is
communicating.

Alarm Code A404 -- Fire Shutdown

This alarm occurs when the shutdown input is either open or
closed depending upon its configuration. This alarm is usually
caused by an auxiliary device that is trying to shut down the unit,
e.g., smoke detector. The configuration for this switch input can be

found at variable Configuration→UNIT→FS.SW. Verify that the
configuration is set correct, verify the wiring and auxiliary device.
This alarm resets automatically.

Alert Code T408 -- Dirty Air Filter

This alert occurs when the Filter Status switch senses a plugged
filter for 120 continuous seconds after the indoor fan has been
running for 10 seconds. Because the Dirty Air Filter switch can be
configured normally opened or closed, the switch might be open or
closed. The configuration for this switch input can be found at
variable Configuration→UNIT→FL.SW. Verify that the
configuration is set correct and verify the wiring and filter status
switch. The hose should be connected to the low side of the switch.
This alert resets automatically.

Alert Code T409

There are 2 different texts for this alert code. Pressing enter and esc
on the marquee or navigator to expand the T409 alert will show
you one of the below alerts. Make sure the expanded text is read
correctly before troubleshooting.

S Fan Status Switch On, Fan Contactor Off

This alarm occurs when the fan status switch has sensed that the

indoor fan has been on for 10 seconds and the indoor fan

feedback has determined that the indoor fan should be off.

Because the Fan Status switch can be configured normally

opened or closed, the switch might be open or closed. The

configuration for this switch input can be found at

Configuration→UNIT→FN.SW. Verify that the configuration

is set correctly. Verify the wiring and fan status switch. The hose

should be connected to the high side of the switch. If the IDF is

configured to shut down the unit when this alarm occurs

(Configuration→UNIT→IDF.F = YES), then this alarm can

only be reset manually and the unit is shut down. If the IDF is

not configured to shut the unit down when this alarm occurs

(IDF.F = NO), then this alarm resets automatically and no

specific control action is taken.

S Fan Status Switch Off, Fan Contactor On

This alert occurs when the fan status switch has sensed that the

indoor fan has been off for 10 seconds and the indoor fan

feedback has determined that the indoor fan should be on.

Because the Fan Status switch can be configured normally

opened or closed, the switch might be open or closed. The

configuration for this switch input can be found at

Configuration→UNIT→FN.SW. Verify that the configuration

is set correctly. Verify the wiring and fan status switch. The hose

should be connected to the high side of the switch. If the IDF is

configured to shut down the unit down when this alert occurs

(Configuration→UNIT→IDF.F = YES), then this alarm can

only be reset manually and the unit is shut down. If the IDF is

not configured to shut the unit down when this alert occurs

(IDF.F = NO), then this alert resets automatically and no specific

control action is taken.

Alert Code T414

There are 6 different alerts under this one alert code. Pressing enter
and esc on the marquee or navigator to expand the T414 alert will
show you one of the below alerts. All these alerts are generated by
the Belimo actuator and reported to the ECB. These alerts can only
occur if the ECB is controlling the actuator digitally through MFT.

S Economizer Damper Actuator Out of Calibration

This alert occurs when the economizer actuator reports a control

angle (Operating Modes→ECON→C.ANG) less than the

minimum control angle (Configuration→ECON→M.ANG).

27

48/50PD

Initiate economizer calibration (Service Test→INDP→ E.CAL)

using the Service Test menu. The economizer calibration

procedure will try to find new maximum open and closed

positions. If the alert does not clear automatically after the

calibration procedure is complete, investigate what is limiting

economizer rotation. After that step, run another calibration, but

first power off unit (spring return the damper), loosen the

actuator clamp, and while pushing the damper closed tighten the

clamp. This alert resets automatically.

S Economizer Damper Actuator Torque Above Load Limit

This alert occurs when the actuator load is too high. Investigate

to determine what is increasing damper load and verify that the

actuator is the correct size for the unit. This alert resets

automatically.

S Economizer Damper Actuator Hunting

This alert occurs when the commanded damper position is

changing too rapidly. The stop jog ration must be less than 21%

to clear this alert. Leave the actuator powered with no signal for

a few hours to allow the ratio to decrease (may have to wait

longer than a few hours). If the alert continues, determine if the

ECB or actuator is bad. This alert resets automatically.

S Economizer Damper Stuck or Jammed

This alarm occurs when the actuator senses it can no longer

move. Investigate what is stopping the rotation of the actuator

and fix. This alert resets automatically.

S Economizer Damper Actuator Mechanical Failure

This alert occurs when the actuator senses a catastrophic failure.

Investigate actuator and replace if necessary. This alert resets

Excessively

automatically.

S Economizer Damper Actuator Direction Switch Wrong Position

This alert occurs when the economizer damper direction switch

48/50PD

is in the wrong position. The direction switch should be in the

clockwise position and the actuator should be mounted so that

the CW face of the actuator is accessible. Correct if necessary.

This alert clears automatically.

Alert Code T415 -- IAQ Input Out of Range

This alert occurs when the IAQ input (on ECB) is less than 3.5 mA
and the sensor is configured as installed. IAQ operation will be
disabled. Check sensor and wiring. This alert clears automatically.

Alert Code T416 -- OAQ Input Out of Range

This alert occurs when the OAQ input (on ECB) is less than 3.5
mA and the sensor is configured as installed. OAQ operation will
be disabled. Check sensor and wiring. This alert clears
automatically.

28

Table 8 — ComfortLink™ Alarm Codes

ALARM

OR

ALERT

NUMBER

T051

T064

T066

T073 Outdoor Air Temperature Thermistor Failure

T074 Space Temperature Thermistor Failure No heating or cooling Automatic

T075 Supply Air Temperature Thermistor Failure No cooling mode Automatic

T076 Return Air Thermistor Failure

T077 Space Relative Humidity Sen sor Failur e

T092

T102 Compressor A1 Current Sensor Failure

T110

T126

T133

T143

T153 Real Timeclock Hardware Failure

A154 Serial EEPROM Hardware Failure Unit Shutdown Automatic Software failure or MBB failure

T155 Serial EEPROM Storage Failure Error Unit operation errors Automatic Software failure or MBB failure
A156 Critical Serial EEPROM Storage Fail Error Unit Shutdown Automatic Software failure or MBB failure
A157 A/D Hardware Failure Unit Shutdown Automatic Software failure or MBB failure

A163

* See Legend on next page

Digital Compressor Control Board Alarm No action Automatic See the DSC’s LEDs for troubleshooting

Compressor A1 Safety Trip Add Strike for Circu it A Automatic

Service Test --- Compressor A1 Safety Trip Add Strike for Circuit A Automatic

Compressor A1 Current Detected After
Turnof f
Service Test --- Compressor A1 Current
Detected After Turnoff
Circuit A Saturated Condensing Temp
Thermistor Failure
Circuit A Saturated Suction Temperature
Thermistor Failure

Circuit A Suction Pressure Transducer
Failure

Circuit A Loss of Charge Shutdown Circuit A Manual Low refrigerant or faulty suction pressure transducer
Service Test --- Circuit A Loss of Charge Shutdown Circuit A Manual Low refrigerant or faulty suction pressure transducer

Circuit A High Discharge Pressure Shutdown Circuit A Automatic

Service Test --- Circuit A High Discharge
Pressure

Circuit A Low Refrigerant Pressure Add Strike for Circuit A Automatic

Service Test --- Circuit A Low Refrigerant
Pressure

Circuit A Failure To Pressurize Add Strike for Circuit A Automatic Wiring causing reverse rotation or faulty compressor
Service Test --- Circuit A Failure To
Pressurize

Circuit A Down Due to Failure Shutdown Circuit A Manual

Service Test --- Circuit A Down Due to
Failure

DESCRIPTION

ACTION TAKEN BY

CONTROL

Turn o f f all

compressors

Turn o f f all

compressors

Use OAT to control

Outdoor fans

No Cooling Automatic Suction transducers internally forced inactive

No cooling with

economizer

No differential DB

crossover

If RH.S = Yes, then no

indoor hu midity control

Shutdown Circuit A Manual

If C S.A1 = Enable,

then no T051 current

alarm

Shutdown Circuit A Automatic

Add Strike for Circuit A Automatic

Add Strike for Circuit A Automatic Wiring causing reverse rotation or faulty compressor

No time and date

schedul e operation

Shutdown Circuit A Manual

RESET

METHOD

Automatic

Automatic

Automatic

Automatic

Automatic

Automatic

Automatic

Automatic

PROBABLE CAUSE

Current Sensing turned on (CS.A1 = Enable) and
should be off
Current Sensing turned on (CS.A1 = Enable) and
should be off
Current Sensing turned on (CS.A1 = Enable) and
should be off
Current Sensing turned on (CS.A1 = Enable) and
should be off
Faulty, shorted, or open thermistor caused by wiring
error or loose connection.

Faulty, shorted, or open thermistor caused by wiring
error or loose connection.
Faulty, shorted, or open thermistor caused by wiring
error or loose connection.
Faulty, shorted, or open thermistor caused by wiring
error or loose connection.
Faulty, shorted, or open thermistor caused by wiring
error or loose connection.
Faulty, shorted, or open sensor caused by wiring
error or loose connection.
Faulty transducer, faulty 5 ---V power supply, or loose
connection

Current Sensing turned on (CS.A1 = Enable) and
should be off

An overcharged system, high outdoor ambient
temperature coupled with dirty outdoor coil, plugged
filter drier, or a faulty high --- pressure switch.
An overcharged system, high outdoor ambient
temperature coupled with dirty outdoor coil, plugged
filter drier, or a faulty high --- pressure switch.
Low refrigerant charge, dirty filters, evaporator fan
turning backwards, loose or broken fan belt, plugged
filter drier, faulty transducer, excessively cold return
air, or stuck open economizer when the ambient
temperature is low.
Low refrigerant charge, dirty filters, evaporator fan
turning backwards, loose or broken fan belt, plugged
filter drier, faulty transducer, excessively cold return
air, or stuck open economizer when the ambient
temperature is low.

No time/date configured, software failure, or MBB
failure

Circuit has 3 strikes or has been locked out by
another alarm
Circuit has 1 strike or has been locked out by another
alarm

48/50PD

29

Table 8 — ComfortLink™ Alarm Codes (cont)

ALARM

OR

ALERT

NUMBER

T178

T179

T180

A200 Linkage Timeout Error --- Comm Failure

A404 Fire Shutdown Unit Shutdown Automatic Smoke detected by smoke detector

T408 Dirty Filter Alert Generated Automatic Dirty Filter

T409

48/50PD

T414

T415 IAQ Input Out of Range No IAQ Operations Automatic

T416 OAQ Input Out of Range No OAQ Operations Automatic

LEGEND

ECB -- Economizer Control Board
IGC -- Integrated Gas Controller
MBB -- Main Base Board
OAT -- Outdoor--Air Thermistor

Loss of Communication with the Capacity
Control Board
Loss of communication with the Economizer
Control Board
Loss of communication with the Economizer
Actuator

Fan Status Switch ON, Fan Contactor OFF

Fan Status Switch OFF, Fan Contactor ON

Economizer Damper Actuator Out of
Calibration
Economizer Damper Actuator Torque Above
Load Limit
Economizer Damper Actuator Hunting
Excessively

Economizer Damper Stuck or Jammed Alert Generated Automatic

Economizer Damper Actuator Mechanical
Failure
Economizer Damper Actuator Direction
Switch Wrong

DESCRIPTION

ACTION TAKEN BY

CONTROL

Unit shutdown ---HVAC

disable

No economizer

operation

No economizer

operation

No Linkage Operation

fall back to local SPT

If IDF.F = Yes, then Unit

Shutdown

If IDF.F = Yes, then Unit

Shutdown

Alert Generated Automatic

Alert Generated Automatic Actuator load too high. Check damper load.

Alert Generated Automatic Damper position changing too quickly.

Alert Generated Automatic Check actuator and replace if necessary.

Alert Generated Automatic Actuator direction control switch (CCW, CW) wrong.

RESET

METHOD

Automatic

Automatic

Automatic Communication wiring problem with actuator.

Automatic

If IDF.F =

YES, then

Manual,
otherwise
automatic

If IDF.F =

YES, then

Manual,
otherwise
automatic

Communication wiring problem with AUX1 or faulty
MBB, ECB, or AUX1
Communication wiring problem with ECB or faulty
MBB, ECB, or AUX1

Received a table write from Linkage before, now not
receiving any linked commands

Bad Fan Status Switch. Configuration incorrect.

Tripped Circuit Breaker. Broken belt. Bad indoor fan
motor. Configuration incorrect. Bad fan status switch.

Calibrate economizer (E.CAL). If problem still exist
then determine what is limiting economizer rotation.

No economizer motion. Check damper blades, gears,
and actuator.

Bad sensor, bad wiring, or sensor configured
incorrectly.
Bad sensor, bad wiring, or sensor configured
incorrectly.

PROBABLE CAUSE

Cooling Troubleshooting

Use the Scrolling Marquee display or a CCN device to view the
cooling status display and the cooling diagnostic display (see
Appendix A) for information on the cooling operation. Check the
current alarms and alarm history for any cooling alarm codes and
correct any causes. (See Table 9.)

Verify any unique control configurations per installed site
requirements or accessories. If alarms conditions are corrected and
cleared, operation of the compressors and fans may be verified by
using the Service Test mode. (See Table 5.) See Table 9 for general
cooling service analysis.

30