Bard MC4002, MC4002-A, MC4002-AC, MC4002-B, MC4002-BC Installation Instructions & Replacement Parts List

INSTALLATION INSTRUCTIONS

&

REPLACEMENT PARTS LIST

MC4002 SERIES SOLID STATE

DUAL UNIT LEAD/LAG CONTROLLER

Bard Manufacturing Company, Inc.
Bryan, Ohio 43506

www.bardhvac.com

Manual : 2100-614I
Supersedes: 2100-614H
Date: 7-13-18

Page 1 of 43

CONTENTS

Getting Other Information and Publications 3
MC4002 General Information

Shipping Damage ............................................... 4

General ............................................................. 4

Theory of Operation ............................................ 4

Controller Certifications ....................................... 4

Specifications/Features for Basic Controller

MC4002 Basic Controller .................................... 5

Mounting the Controller

Installation Instructions ...................................... 5

Temperature Sensors

Two Optional Sensor Inputs ................................. 5

Temperature Sensor Logic

Using Multiple Sensors ....................................... 5

Controller Input/Output Specifications

MC4002 Controller Connections .......................... 6

Specifications/Features for Alarm Boards

MC4002-A with Optional Base Alarm ................... 6

MC4002-B with Enhanced Version Alarm .............. 6

Low Voltage Field Wiring

Circuitry in the MC4002 ..................................... 7

Controller Grounding

Earth ground ...................................................... 7

Controller Power-Up

Time Delay on Power-Up ...................................... 7

Fire Suppression Circuit

Disabling the MC4002 ........................................ 7

Staging Delay Periods

Stages 1 - 4 ....................................................... 7

Blower Operation

Various Blower Options ........................................ 7

Advance (Swap) Lead/Lag Unit Feature

Manual Switching of Units .................................. 7

Accelerate Timer Feature

Testing the Timer Function .................................. 7

General Programming Overview

Buttons & Function ............................................. 8

Humidity Control Option

Adding Optional Humidity Control ........................ 9

Cooling Operating Sequences

for Alternating Lead/Lag/Lead/Lag Config .............. 9

Cooling Operating Sequences

for Non-Alt Lead/Lead/Lag/Lag Config ................. 11

Heating Sequence of Operation ............................. 13

Specifications Opt. Remote Comm. Board .............. 14

CB5000 Communications Board ........................ 14

Controller Wiring

Refer to Connection Diagram ............................. 18

Security (Locking) Feature

Locking and Unlocking the MC4002 .................. 18

Generator Run Feature

Standby Generator Disable Operation.................. 18

Backup DC Power Connection

Input Connections Available .............................. 18

Alarm Wiring ....................................................... 37

2nd Stage Cooling Alarm ...................................... 37

Refrigerant Pressure Alarms .................................. 37

Emergency Ventilation Sequence ........................... 37

Programming Instructions ..................................... 40

Figures

Figure 1 Controller Connections 1-Stage (WA/WL, W**A/

W**L Series) A/C w/No Economizers ...........19

Figure 2 Controller Connections 1-Stage (W**AA/ W**LA

Series) A/C w/No Economizers ....................20

Figure 3 Controller Connections 2-Stage (WA*S/WL*S

Series) A/C - No Economizers .....................21

Figure 4 Controller Connections 1-Stage (WA/WL, W**A/

W**L Series) A/C - No Econo with Alarm Board

& CB5000 Comm. Board ...........................22

Figure 5 Controller Connections 1-Stage (W**AA/ W**LA

Series) A/C - No Econo with Alarm Board &

CB5000 Comm. Board ..............................23

Figure 6 Controller Connections 2-Stage (WA*S/WL*S

Series) A/C - No Econo with Alarm Board &

CB5000 Comm. Board ..............................24

Figure 7 Controller Connections 1-Stage (WA/WL, W**A/

W**L Series) A/C-Older EIFM Econo ...........25

Figure 8 Controller Connections 2-Stage (WA*S/WL*S ..

Series) A/C-Older Style EIFM Econo ............26

Figure 9 Controller Connections 1-Stage (WA/WL, W**A/

W**L Series) A/C w/Older Style EIFM Econo &

w/Alarm Board/CB5000 Comm. Board .........27

Figure 10 Controller Connections 2-Stage (WA*S/WL*S ..

Series) A/C w/Older Style EIFM Econo &

w/Alarm Board/CB5000 Comm. Board ........28

Figure 11 Controller Connections 1-Stage (WA/WL, W**A/

W**L Series) A/C w/ECONWMT Econo ..........29

Figure 12 Controller Connections 1-Stage (W**AA/ W**LA

Series) A/C w/WECOP Econo .......................30

Figure 13 Controller Connections 2-Stage (WA*S/WL*S

Series) A/C w/ECONWMT Econo ..................31

Figure 14 Controller Connections 1-Stage (WA/WL, W**A/

W**L Series) A/C w/ECONWMT Econo &

w/Alarm Board/CB5000 Comm. Board .........32

Figure 15 Controller Connections 1-Stage (W**AA/ W**LA

Series) A/C w/WECOP Econo & w/Alarm Board/

CB5000 Comm. Board ..............................33

Figure 16 Controller Connections 2-Stage (WA*S/WL*S

Series) A/C w/ECONWMT Econo & w/Alarm

Board/CB5000 Comm. Board .....................34

Figure 17 Controller Connections Heat Pumps -

No Economizers ........................................35

Figure 18 Controller Connections Heat Pumps -

No Economizers w/Opt. Alarm Board &

CB5000 Communication Board ..................36

— — — Alarm LED Display Board ........................... 37

Figure 19 Alarm Board Connections for Normally Closed

"NC" Open-On-Alarm Strategy .....................38

Figure 20 Alarm Board Connections for Normally Open

"NO" Close-On-Alarm Strategy ....................39

— — — MC Series Label ........................................ 41

Figure 21 Parts List Description Diagram ...................42

Tables

Table 1 Hook-Up Diagram Selection .......................19

— — — Parts List .................................................43

Manual 2100-614I
Page 2 of 43

Getting Other Information and Publications

These publications can help when installing the air
conditioner or heat pump. They can usually be found
at the local library or purchased directly from the
publisher. Be sure to consult the current edition of
each standard.

Standard for the Installation ........ANSI/NFPA 90A

of Air Conditioning and
Ventilating Systems

Standard for Warm Air Heating .....ANSI/NFPA 90B

and Air Conditioning Systems

For more information, contact these publishers:

ACCA Air Conditioning Contractors of America

1712 New Hampshire Avenue, NW
Washington, DC 20009
Telephone: [phone]
Fax: [phone]

ANSI American National Standards Institute
11 West Street, 13th Floor
New York, NY 10036
Telephone: [phone]
Fax: [phone]

ASHRAE American Society of Heating, Refrigerating,
and Air Conditioning Engineers, Inc.

1791 Tullie Circle, N.E.
Atlanta, GA 30329-2305
Telephone: [phone]
Fax: [phone]

BARD Bard Manufacturing Company, Inc.

1914 Randolph Drive
Bryan, OH 43506
Telephone: [phone]
Fax: [phone]

Manual 2100-614I
Page 3 of 43

** IMPORTANT **

The equipment covered in this manual is to be installed
by trained, experienced service and installation
technicians. Please read entire manual before
proceeding.

SHIPPING DAMAGE

Upon receipt of equipment, the carton should be
checked for external signs of shipping damage. If
damage is found, the receiving party must contact
the last carrier immediately, preferably in writing,
requesting inspection by the carrier’s agent.

GENERAL

These instructions explain the operation, installation
and troubleshooting of the MC4002 controller.

All internal wiring is complete. Only attach low voltage
field wiring to designated terminal strips.

The MC4002 is for use with units with or without
economizers, can be configured for use with heat
pumps, and has a dehumidification control feature
if an optional humidity controller is connected.
Dehumidification control cannot be used with heat
pump.

Each unit should be sized to handle the total load of
the structure if 100% redundancy is required.

It is recommended that a 5-minute compressor time
delay relay be installed in each unit if not so equipped.

The MC4002 controller can be configured for
alternative (lead/lag/lead/lag) sequence, which is
default setting. It can be changed to non-alternating
(lead/lead/lag/lag) sequence as required for special
applications or user preference.

The MC4002 can be equipped with one of two alarm
boards, and these can be factory-installed or installed
at any time in the field if so desired.

Should the base controller alone be initially installed,
it is easily upgradeable by simple snap-in, plug-in field
installation of either one of the alarm boards, requiring
only the connection of the building alarm circuitry to
the alarm boards. Form C dry contact alarm relays
are used, offering both NO and NC switching to meet
the user’s specific alarm protocol, providing complete
flexibility to meet any user's requirements. All alarm
actuations are individually indicated on the controller
front panel.

There is an Ethernet-based remote communication
option that can be either factory or field installed. See
section on Communication Module.

CONTROLLER CERTIFICATIONS

The MC4002 main controller board, optional alarm
boards, optional communication module, and remote
sensors have undergone extensive testing for immunity
and emissions. This system is FCC-compliant, in
accordance with CE requirements, and meets the
following standards:

MC4002 Series

Master Controller

The MC4002 controller is suitable for both 50 and 60
HZ operation, and is fully configurable such that it can
be used in virtually any installation. See Controller
Programmable Features and Default Settings.

THEORY OF OPERATION

The controller is used to control two wall mount air
conditioners from one control system. It provides
total redundancy for the structure and equal wear on
both units. It can be used with units with or without
economizers and it is recommended that both units be
equipped alike.

CONFORMS TO UL STD 916
CERTIFIED TO
CSA STD C22.2 NO. 205

Manual 2100-614I
Page 4 of 43

This device complies with FCC Rule Part 15, Subpart
B, Class A. Operation is subject to the following two
conditions:

1. This device may not cause harmful interference

2. This device must accept any interference
received, including that which may cause
undesired operation.

This device complies with CE Standards EN55011/
EN50081 and EN55024 for ISM Equipment, Class A.

This ISM device also complies with Canadian ICES –

001.

Bard Manufacturing Company, Inc.

Bryan, OH 43506

SPECIFICATIONS/FEATURES FOR BASIC
CONTROLLER

MC4002 Basic Controller

•Input power: 18-32 VAC, 60/50Hz, power is supplied from
A/C #1 and/or A/C #2

•Isolation circuitry: no line or low voltage phasing required

•Backup power: connection for -24 VDC or -48 VDC (-20
to -56V) maintains microprocessor operation, front panel
indication & alarm relay operation during commercial power
outages.

•Digital display: 4-character LCD

•Temperature display: F or C

•HVAC outputs: Form A (NO) relays (1A @ 24 VAC)

•Cooling control stages:
2 for each A/C unit (4 total) when configured for economizers
1 for each A/C unit (2 total) when configured for no economizers

•Heating Control stages:

1 for each A/C unit, 2 for each heat pump if so configured

•Dehumidification circuit: requires optional humidity

controller as input signal

•Operating temperature range: 0 to 120F (-18 to 49C)

•Storage temperature range: -20 to 140F (-29 to 60C)

•Temperature accuracy: +/- 1F from 60-85F (16-30C)

+/- 1% outside 60-85F

•Lead/lag changeover time: 0 to 30 days

•Timing accuracy: +/- 1%

•Inter-stage time delay: 10 seconds between stages

•Inter-stage differential:

Stage 1 to 2 - Range 2-6F, default is 4
Stage 2 to 3 - Range 2-3F, default is 2
Stage 3 to 4 - Range 2-3F, default is 2

•On-Off differential: 2F (1C) is standard, 4F (3C) when

“excessive cycling” mode is enabled

•Cooling setpoint range: 65 to 90F (18.3 to 32.2C)

•Comfort setting-Cooling 72F (22C), Heating 68F(20C), for

1 hour

•Dead band (difference between cooling and heating

setpoints): 2F to 40F (1.1C to 22.2C)

•Fire/smoke interface: standard NC circuit jumper, remove

for connection to building system control, shuts down
outputs to both A/C units immediately

•Memory: EEPROM for setpoint and changeable parameters

(maintains settings on power loss)

•Space temperature sensors: One (1) local is standard, will

accept up to twp (2) optional 35' remote sensors, Bard part
number 8612-023A. When multiple sensors are used,
temperatures are averaged

•Controller Enclosure: 20-gauge pre-painted steel, 9.25"W

x 13.50"H x 3.00"D, hinged cover, thirteen (13) .875"
diameter electrical knockouts

•LEDs for basic controller: Lead unit, Cooling stages 1

through 4, Heating Stages 1 – 4, Dehumidification operation

•Six (6) Push-button controls: On/Off switch-Change lead

unit-Increase and Decrease setpoints-Program/Save-Comfort.

MOUNTING THE CONTROLLER

Included in the controller carton is the controller and
installation instructions.

The controller should be installed on a vertical wall
approximately 4 feet above the floor-away from drafts and
outside doors or windows. Four (4) mounting holes are
provided for mounting to the wall and 7/8" holes for conduit
connections are provided in both the base, sides and top of
the controller.

TEMPERATURE SENSORS

The standard (local) temperature sensor has 12" leads and
comes installed from the factory.

A secondary sensor is located internally on the main controller
board and serves as a reference and back-up sensor to the
local sensor. If the difference between the two sensors is
less than the differential setpoint, the local sensor will be
used as the controller's temperature point of reference. The
differential is adjustable from 12-20°F. 12°F is the default
setting. If the difference between the two sensors is greater
than the differential set-point, then the controller will check
to determine if the on-board sensor is reading a temperature
that is between the SP (set-point), plus the differential and the
SP minus the DB (dead-band) minus the differential. If it is,
the on-board sensor will become the valid sensor reading and
the controller will ignore the local sensor reading. If not, then
the controller, will still use the local sensor reading. This is to
add additional levels of operational capability in the rare event
the local sensor fails. If the controller is operating in this
mode, it is indicated by the lower left decimal point flashing in
the display. If this feature is not desired, set the differential
set-point to OFF. This disables the on-board sensor. This may
be necessary if the controller is located in one room and the
local sensor has been relocated to a different room. Note: For

purposes of testing when the local sensor is manually driven
higher or lower by applying warm or cool water to the probe the
on-board sensor is inhibited for the first 30-minutes following
power up, or when power is cycled off and back on.

The controller is designed to accept 1 or 2 additional sensors
and those have 35-foot leads. The Bard part number for the
optional sensor with 35-foot leads is 8612-023A. These can
be installed as required in the structure to address hot spots,
barriers to airflow, etc. If a remote sensor(s) is used, the on­board sensor is disabled. The local sensor remains active.

It is recommended that the sensor lead wires be installed in
conduit for protective purposes.

NOTE: All sensors are polarity sensitive. The
copper lead must connect to terminal CU, and the
silver lead to AG. Sensors are solid state, not RTD.
Use only sensors supplied by Bard. Sensor leads
can be extended up to 200 feet. Use 18-gauge
twisted pair with soldered connections.

TEMPERATURE SENSOR LOGIC

The standard local (LSEn) sensor monitors the temperature at
the controller location. If this is the only sensor connected,
it will control the temperature read-out, the space (building)
temperature, and also be used for Low and High Temperature
alarm functions.

If one or more REMOTE sensors are installed and connected
(Rem 1 or Rem 2), the temperature read-out will display

and

Manual 2100-614I
Page 5 of 43

the building will be controlled to an average of all
connected sensors. If there is more than 10F difference
from the highest to the lowest connected sensor, the
actual control will be governed by the hottest sensor for
cooling and the coldest sensor for heating.

If alarm boards are utilized, the highest reading of any
connected sensor will be used for high temperature
alarm and the lowest reading sensor will be used for low
temperature alarm. The on-board sensor is ignored if
two (2) or more sensors are connected to the Local, Rem
1 or Rem 2 sensor inputs.

BASIC MC4002 CONTROLLER
INPUT/OUTPUT SPECIFICATIONS

MC4002 CONTROLLER CONNECTIONS

Located on Main Controller Board

Unit #1 C – 24VAC common

R – 24VAC hot
G – fan (Form A, NO)
Y1 – 1
Y2 – 2
W – heat (Form A, NO)
Unit #2 C – 24VAC common
R – 24VAC hot
G – fan (Form A, NO)
Y1 – 1
Y2 – 2
W – heat (Form A, NO)
F1-F2 Fire/smoke interface
Shipped with jumper installed (a)
48Vdc Back-up power input

-24Vdc or –48Vdc

-20V to –56V range

Local Main sensor, 12-inch leads
CU – copper, AG – silver
Polarity sensitive
Rem 1 Optional remote indoor sensor
CU – copper, AG – silver
Polarity sensitive
Rem 2 Optional remote indoor sensor
CU – copper, AG – silver
Polarity sensitive
Gen Generator interface G1-G2
Shipped with jumper installed (a)
H1-H2 Humidity controller input
Requires optional controller
Field installed

(a) These connections require either jumper or Normally
Closed (NC) relay contact at the Fire/Smoke and
Generator interface for Controller to function.

Note: All alarm and output relays are dry contacts
rated 1A @ 24 VAC.

st

-stage cool (Form A, NO)

nd

-stage cool (Form A, NO)

st

-stage cool (Form A, NO)

nd

-stage cool (Form A, NO)

NOTE:

Sensors are

solid state,

not RTD.

Use Bard

sensors only.

Note: All alarm relay outputs have 10-second delay
before issuing to protect against nuisance alarm
signals.

SPECIFICATIONS/FEATURES FOR
ALARM BOARDS

MC4002-A w/Optional Base Alarm Board
(Inputs/Outputs)

NOTE: If this alarm board was not originally factory
installed, it can be field-installed at anytime. Bard
part number is AB3000-A.

Inputs

Lockout 1 2,3 – input from HVAC #1
Lockout 2 2, 3 – input from HVAC #2

Outputs

Smoke/Fire Form C (SPDT)
Lockout 1 Form C (SPDT)
Refrigerant alarm HVAC #1
Lockout 2 Form C (SPDT)
Refrigerant alarm HVAC #2
Power Loss 1 Form C (SPDT)
Power loss HVAC #1
Power Loss 2 Form C (SPDT)
Power loss HVAC #2
Low Temp Form C (SPDT)
Low temperature alarm
High Temp 1 Form C (SPDT)
High temperature alarm #1

MC4002-B w/Enhanced Version Alarm Board
(Additional Outputs) plus MC4002-A Inputs/Outputs

NOTE: If this alarm board was not originally
factory installed, it can be field-installed at
anytime. Bard part number is AB3000-B.

High Temp 2 Form C (SPDT)
High temperature alarm #2
Controller Form C (SPDT)
Controller failure alarm – see note (a)
Econ 1 E, F - Form A (NO) – see note (b)
Econ 2 E, F - Form A (NO) – see note (b)

nd

Stage Form C (SPDT) – see note (c)

2
2

(a) Alarm will only activate if main board processor
fails or if alarm board to main board cable is damaged.

(b) Make these connections to terminals E & F
in HVAC 1 and 2 respectively if desired to have
economizers open for emergency ventilation at High
Temp Alarm #2 setpoint condition.

(c) For units with 2-stage compressors, 2nd stage
cooling alarm activates on cooling Stage 3 initiation.

nd

-stage cooling alarm

Alarm relays can be wired for NO (close on alarm) or NC (open on alarm) strategy. Alarm relays can be used individually
if there are enough available building alarm points, or can be arranged into smaller groups or even a single group so that
all alarm capabilities can be utilized. When multiple alarms are grouped together and issued as a single alarm there will
be no off-site indication of which specific problem may have occurred, only that one of the alarms in the group has been
triggered. The individual alarm problem will be displayed on the LED display on face of the controller.

Manual 2100-614I
Page 6 of 43

LOW VOLTAGE FIELD WIRING

The MC4002 is powered from the air conditioners that it
is controlling, 24 VAC (18-32V) low voltage only.

Circuitry in the MC4002 isolates the power supplies of
the two air conditioners so that no back feeds or phasing
problems can occur. Additionally, if one air conditioner
loses power, the MC4002 and the other air conditioner
are unaffected and will continue to operate normally.

Connect the low voltage field wiring from each unit per the
low voltage field wiring diagrams in Section on “Controller
Wiring”. NOTE: Maximum of 18-gauge control wiring

should be used. Using heavier gauge wiring can create
excessive stress on the control board as door is opened
and closed. Create a wiring loop so the door can open
and close without stressing terminal blocks.

CONTROLLER GROUNDING

A reliable earth ground must be connected in addition to
any grounding from conduit. Grounding lugs are supplied
for this purpose.

CONTROLLER POWER-UP

Whenever power is first applied to the controller, there
is a twenty (20) second time-delay prior to any function
(other than display) becoming active. This time-delay
is in effect if the controller On/Off button is used
when 24VAC from air conditioners is present, and also
if controller is in “ON” position and 24VAC from air
conditioners is removed and then restored.

FIRE SUPPRESSION CIRCUIT

To disable the MC4002 and shut down both air
conditioners, terminals F1 and F2 may be used. The F1
and F2 terminals must be jumpered together for normal
operation. A normally closed (nc) set of dry contacts may
be connected across the terminals and the factory jumper
removed for use with a field-installed fire suppression
system. The contacts must open if a fire is detected.
See appropriate connection diagram - Figures 1, 2 or 3
for this connection. Contacts should be rated for pilot
duty operation at 2 amp 24VAC minimum. Shielded wire
(22-gauge minimum) must be used, and the shield must
be grounded to the controller enclosure.

IMPORTANT NOTE: Older Bard R-22 models employ an
electronic blower control that has a 60-second blower
off-delay. Current production R-410A models do not
use a blower off-delay device and the remainder of this
(paragraph) does not apply. In order to have immediate
shutdown of the blower motor, in addition to disabling
the run function of the air conditioners will require a
simple wiring modification at the blower control located
in the electrical control panel of the air conditioners
being controlled by the lead/lag controller. To eliminate
the 60-second blower off-delay, disconnect and isolate
the wire that is factory-connected to the “R” terminal
on the electronic blower control, and then connect a
jumper from the “G” terminal on the blower control to

the “R” terminal on the blower control. The electronic
blower control will now function as an on-off relay with
no off-delay, and the blower motor will stop running
immediately when the F1-F2 fire suppression circuit is
activated (opened).

STAGING DELAY PERIODS

The following delays are built in for both cooling and
heating:

Stage 1 – 0 seconds for blower (if not already on as

continuous)
10 seconds for cooling or heating output

Stage 2 – 10 seconds after Stage 1 for blower

10 additional seconds for cooling or heating
output

Stage 3 – 10 seconds after Stage 2

Stage 4 – 10 seconds after Stage 3

Note: For cooling Stages 1 and 2, the stage LED will

blink for 10 seconds while the cooling output is delayed
after that stage is called for. There is also a delay after
the stage is satisfied, and after the LED stops blinking,
the stage will turn off. There is a minimum 10-second
delay between stages 2 & 3, and 3 & 4, but no delayed
output when stage is turned on or off, and LED for those
stages will not blink.

BLOWER OPERATION

The controller can be configured to have main HVAC
blowers cycle on and off on demand; have all blowers
run continuously; or have the lead unit blower run
continuously with the lag unit blower cycling on
demand. Default setting is the blower(s) start and stop
on demand. There is also an option to have all blowers
cycle on if one remote sensor is connected, and a
temperature difference of more than 5F between any two
sensors is observed. This helps to redistribute the heat
load within the structure and should reduce compressor
operating time.

When any of the stages are satisfied, the stage LED will
blink for ten (10) seconds before the stage is actually
turned off.

ADVANCE (SWAP) LEAD/LAG UNIT
FEATURE

Pressing the Advance button for one (1) second will cause
the lead and lag units to change positions. This may be
useful during service and maintenance procedures.

ACCELERATE TIMER FEATURE

Pressing the UP arrow button for five (5) seconds
will activate an accelerate (speed-up) mode, causing
the normal changeover time increments of days to
be reduced to seconds. Example: 7 days becomes
7 seconds. When “ACC” displays, release button.
Whichever LED is on, indicating lead unit will blink over
for each second until the controller switches. This is a
check for the timer functionality.

Manual 2100-614I
Page 7 of 43

GENERAL PROGRAMMING OVERVIEW

MC4002 CONTROLLER BUTTONS AND FUNCTION

On/Off Button

1. Press and release the On/Off button to turn On controller, 4-character display will illuminate and Lead unit LED will light.

2. Press and release the On/Off button to turn Off controller. Controller will go dark and A/C units will stop.

Comfort Button

1. Press and release the Comfort button to change the Cooling Setpoint to 72F and the Heating Setpoint to 68F for a period of 1 hour.

2. Setpoints will return to the programmed settings automatically after 1 hour.

3. Pressing the Comfort button during the 1 hour period will deactivate the Setpoint change.

4. The temperature display will flash the current temperature while in override mode.

Program Button

1. Press the Program button and release it when the message “Prog” appears on the display.

2. Refer to Programming Instructions and follow these commands to change from Default settings.

Advance/Change/Save Button

1. Press and release the Advance button to swap lead and lag unit positions.

2. When in Program mode the Down and Up buttons are used to scroll through the programming steps.

3. A flashing display means that the particular function of that programming step is “set”, and the display will alternate between the step

function and the setting.

4. To change the setting press the Change button and the display will stop flashing, allowing change to the setting.

5. Use Down or Up arrows to change setting as desired, and press the Save button and proceed as desired.

6. When done with programming changes press the Program button until display stops flashing and room

temperature is shown.

Up and Down Buttons

These buttons are used to change the settings in conjunction with the Advance/Change/Save button when in programming mode.

CONTROLLER PROGRAMMABLE FEATURES AND DEFAULT SETTINGS

Order/

Display

LSEn Temperature at local (main) sensor — —

cFAn Continuous blower operation None, Lead, Both None

LLCO Lead-Lag changeover time (Days) 1 - 30 days, or 0 for disabled 7

Cbd5 Unit 1 and 2 blowers automatically both run if delta T >5F between any 2 connected sensors Yes or No Yes

OFde 3-minute lead unit & 4-minute lag unit off-delay enabled Yes or No No

LoAL Low temperature alarm setpoint 28 to 65F (-2 to 18C) 45F (7.2C)

HAL1 High temperature alarm level #1 setpoint 70F to 120F (21 to 49C) 90F (32C)

HAL2 High temperature alarm level #2 setpoint 70F to 120F (21 to 49C) 95F (35C)

Locd Controller is locked and no changes can be made. Consult building authority.

Inter-Stage Differential

ISd2 From Stage 1 to Stage 2 2, 3, 4, 5 or 6F 4

ISd3 From Stage 2 to Stage 3 2 or 3F 2

ISd4 From Stage 3 to Stage 4 2 or 3F 2

On/Off Differential (Hysterisis)

CSon Turn "On" above SP for Stage 1 Cooling +1 or 2F 2

CSoF Turn "Off" below SP for Stage 1 Cooling -1, 2, 3 or 4F -2

HSoo All Heating Stages are equal -/+ on & off differential -1/+1 or -2/+2 -2/+2

CoPr

ob5d Differential between Local and On-Board Sensor 12 to 20, OFF 12

Description Range/Choice Default

SP Cooling setpoint temperature 65 to 90F (18 to 32C) 77F (25C)

db Deadband between cooling SP and heating setpoint 2 to 40F (1 to 24C) 17F (9.4C)

r1 Temperature at remote sensor 1 location, if connected — —

r2 Temperature at remote sensor 2 location, if connected — —

deg Controller system operates in F or C F or C F

Alternating Lead-Lag-Lead-Lag sequence or Non-Alternating Lead-Lead-Lag-Lag sequence —

Alt

Yes = Alternating

Heat pump logic enabled — only for 1-stage heat pumps and forces Lead-Lag sequence

HP

(overrides a Non-Alt setting)

crun Minimum 3-minute compressor runtime enabled Yes or No No

Stage 2, 3 and 4 Cooling automatically set same as Stage 1 decisions

1 or 2-stage compressor, if set to 1 the 2nd stage Cooling Alarm activates on Cooling Call 2,
if set to 2 the 2nd stage Cooling Alarm activates on Cooling Call 3

Yes or No Yes

Yes or No No

If locked, display will show
Locd if changes attempted

1 or 2 1

Unlocked

Manual 2100-614I
Page 8 of 43

HUMIDITY CONTROL OPTION

Note: This function is not available if controller is
configured for heat pump.

The standard air conditioning system can be adapted
to perform dehumidification control by addition of a
simple humidity controller that closes-on-rise, and
is connected to terminals H1 and H2 on the main
controller board. Recommended Bard Part #8403-038
(H600A 1014). Both HVAC units must be equipped
with electric heat for this sequence to work properly.
See appropriate connection diagram - Figures 1 - 12 for
this connection:

1. Temperature control always has priority over
dehumidification. If there is any stage of cooling
demand active, the dehumidification sequence is
locked out.

2. If all stages of cooling are satisfied, and relative
humidity is above the setpoint of humidity
controller:

a. The green “Dehumid. Operation” light will come
on, and the lag unit compressor and blower will
operate until the setpoint of humidity controller
is satisfied (or cancelled by a call for cooling).

b. If the space temperature drops to 67F, the
electric heater of the lead unit will cycle to help
maintain building temperature. It will cycle off
at 69F.

c. If space temperature drops to 64F, the Stage 2
Heating light will come on and the lag unit
compressor operating for dehumidification mode
will cycle off until the building temperature rises
above 65F from 1st stage heat and building load.
The green “Dehumid. Operation” light stays on
during this sequence, and when Stage 2 Heating
light is Off, the compressor is On. The electric
heater in lag unit is locked out in
dehumidification mode.

Lag unit outputs G, Y1 and Y2 are all switched on
during dehumidification sequence. This is true
for both alternating and non-alternating controller
configurations.

CAUTION

Humidity controller setpoint should be in 50-60%
relative humidity area: Setting controller to lower
settings will result in excessive operating time and
operating costs for the electric reheat, and in extreme
cases could cause evaporator (indoor) coil freeze-up
if there are periods of light internal equipment (heat)
loading.

COOLING OPERATING SEQUENCES
FOR ALTERNATING LEAD/LAG/LEAD/
LAG CONFIGURATION

1. 1-Stage Compressor Units No Economizer

st

stage cooling setpoint is the setting (SP) input into

1
the controller. Factory default is 77F (25C). On a call
for cooling the blower of the lead unit will come on
immediately (if not already on – See Blower Operation),
and the Stage 1 LED will blink for 10-seconds before
going solid, at which time the compressor will start.

nd

cooling setpoint is 4F (default setting, user

2
selectable 2-6F) warmer than Stage 1. On a call for 2
Stage cooling the blower of the lag unit is turned on (if
not already on – See Blower Operation), and the Stage
2 LED will blink for 10-seconds before going solid, at
which time the compressor will start.

rd

and 4th stages are functional outputs but there is

3
nothing to be controlled.

2. 2-Stage Compressor Units No Economizer

st

stage cooling setpoint is the setting (SP) input into

1
the controller. Factory default is 77F (25C). On a call
for cooling the blower of the lead unit will come on
immediately (if not already on – See Blower Operation),
and the Stage 1 LED will blink for 10-seconds before
going solid, at which time the lead unit compressor will
start in compressor Stage 1 partial capacity operation.

nd

cooling setpoint is 4F (default setting, user

2
selectable 2-6F) warmer than Stage 1. On a call for

nd

Stage cooling the blower of the lag unit is turned

2
on (if not already on – See Blower Operation), and the
Stage 2 LED will blink for 10-seconds before going
solid, at which time the lag unit compressor will start in
compressor Stage 1 partial capacity operation.

rd

cooling setpoint is 2F (default setting, user

3
selectable 2-3F) warmer than Stage 2. On a call for

rd

Stage cooling the Stage 3 LED comes on solid (no

3
delay), and the lead unit compressor will switch to
compressor Stage 2 full capacity operation.

th

cooling setpoint is 2F (default setting, user

4
selectable 2-3F) warmer than Stage 3. On a call for
4th Stage cooling the Stage 4 LED comes on solid
(no delay), and the lag unit compressor will switch to
compressor Stage 2 full capacity operation.

3. 1-Stage Compressor Units with Older EIFM
Economizers (Enthalpy OD Sensor)

1st stage cooling setpoint is the setting (SP) input
into the controller. Factory default is 77F (25C).
On a call for cooling the blower of the lead unit
will come on immediately (if not already on – See
Blower Operation), and the Stage 1 LED will blink
for 10-seconds before going solid, at which time
the lead unit Y1 cooling output turns on. If

nd

the

Manual 2100-614I
Page 9 of 43

outdoor temperature and humidity conditions are below
the setpoint of the economizer control the lead unit
economizer will operate instead of the compressor. If
outdoor conditions are not acceptable for free cooling
the compressor will automatically operate instead of the
economizer.

nd

cooling setpoint is 4F (default setting, user

2
selectable 2-6F) warmer than Stage 1. On a call for 2

nd

Stage cooling the blower of the lag unit is turned on (if
not already on – See Blower Operation), and the Stage
2 LED will blink for 10-seconds before going solid, at
which time the lag unit Y1 cooling output turns on. If
the outdoor temperature and humidity conditions are
below the setpoint of the economizer control the lag
unit economizer will operate instead of the compressor.
If outdoor conditions are not acceptable for free cooling
the compressor will automatically operate instead of the
economizer.

rd

cooling setpoint is 2F (default setting, user

3
selectable 2-3F) warmer than Stage 2. On a call for 3

rd

Stage cooling the lead unit economizer will close and
the compressor will operate.

th

cooling setpoint is 2F (default setting, user

4
selectable 2-3F) warmer than Stage 3. On a call for 4th
Stage cooling the lag unit economizer will close and the
compressor will operate.

4. 1-Stage Compressor Units with Newer
ECONWMT or WECOP Economizers (See Note A)

st

stage cooling setpoint is the setting (SP) input into

1
the controller. Factory default is 77F (25C). On a call
for cooling the blower of the lead unit will come on
immediately (if not already on – See Blower Operation),
and the Stage 1 LED will blink for 10-seconds before
going solid, at which time the lead unit Y1 cooling
output turns on. If the outdoor temperature and
humidity conditions are below the setpoint of the
economizer control the lead unit economizer will
operate instead of the compressor. If outdoor conditions
are not acceptable for free cooling the compressor will
automatically operate instead of the economizer.

nd

cooling setpoint is 4F (default setting, user

2
selectable 2-6F) warmer than Stage 1. On a call for 2

nd

Stage cooling the blower of the lag unit is turned on (if
not already on – See Blower Operation), and the Stage
2 LED will blink for 10-seconds before going solid, at
which time the lag unit Y1 cooling output turns on. If
the outdoor temperature and humidity conditions are
below the setpoint of the economizer control the lag
unit economizer will operate instead of the compressor.
If outdoor conditions are not acceptable for free cooling
the compressor will automatically operate instead of the
economizer.

rd

cooling setpoint is 2F (default setting, user

3
selectable 2-3F) warmer than Stage 2. On a call for 3

rd

Stage cooling the lead unit economizer will continue to

operate as long as outdoor conditions are acceptable,
and the compressor will operate.

th

cooling setpoint is 2F (default setting, user

4
selectable 2-3F) warmer than Stage 3. On a call for 4th
Stage cooling the lag unit economizer will continue to
operate as long as outdoor conditions are acceptable,
and the compressor will operate.

5. 2-Stage Compressor Units with Older EIFM
Economizers

st

stage cooling setpoint is the setting (SP) input into

1
the controller. Factory default is 77F (25C). On a call
for cooling the blower of the lead unit will come on
immediately (if not already on – See Blower Operation),
and the Stage 1 LED will blink for 10-seconds before
going solid, at which time the lead unit Y1 cooling
output turns on. If the outdoor temperature and
humidity conditions are below the setpoint of the
economizer control the lead unit economizer will
operate instead of the compressor. If outdoor conditions
are not acceptable for free cooling the compressor will
automatically operate on compressor Stage 1 partial
capacity instead of the economizer.

nd

cooling setpoint is 4F (default setting, user

2
selectable 2-6F) warmer than Stage 1. On a call for 2
Stage cooling the blower of the lag unit is turned on (if
not already on – See Blower Operation), and the Stage
2 LED will blink for 10-seconds before going solid, at
which time the lag unit Y1 cooling output turns on. If
the outdoor temperature and humidity conditions are
below the setpoint of the economizer control the lag
unit economizer will operate instead of the compressor.
If outdoor conditions are not acceptable for free
cooling the compressor will automatically operate on
compressor Stage 1 partial capacity instead of the
economizer.

rd

cooling setpoint is 2F (default setting, user

3
selectable 2-3F) warmer than Stage 2. On a call for 3
Stage cooling the lead unit economizer will close and
the compressor will operate on full capacity compressor
Stage 2.

th

cooling setpoint is 2F (default setting, user

4
selectable 2-3F) warmer than Stage 3. On a call for 4th
Stage cooling the lag unit economizer will close and
the compressor will operate on full capacity compressor
Stage 2.

6. 2-Stage Compressor Units with Newer
ECONWMT or WECOP Economizers (See Note A)

st

stage cooling setpoint is the setting (SP) input into

1
the controller. Factory default is 77F (25C). On a call
for cooling the blower of the lead unit will come on
immediately (if not already on – See Blower Operation),
and the Stage 1 LED will blink for 10-seconds before
going solid, at which time the lead unit Y1 cooling
output turns on. If the outdoor temperature and
humidity conditions are below the setpoint of the

nd

rd

Manual 2100-614I
Page 10 of 43

economizer control the lead unit economizer will
operate instead of the compressor. If outdoor conditions
are not acceptable for free cooling the compressor will
automatically operate on compressor Stage 1 partial
capacity instead of the economizer.

nd

cooling setpoint is 4F (default setting, user

2
selectable 2-6F) warmer than Stage 1. On a call for 2

nd

Stage cooling the blower of the lag unit is turned on (if
not already on – See Blower Operation), and the Stage
2 LED will blink for 10-seconds before going solid, at
which time the lag unit Y1 cooling output turns on. If
the outdoor temperature and humidity conditions are
below the setpoint of the economizer control the lag
unit economizer will operate instead of the compressor.
If outdoor conditions are not acceptable for free
cooling the compressor will automatically operate on
compressor Stage 1 partial capacity instead of the
economizer.

rd

cooling setpoint is 2F (default setting, user

3
selectable 2-3F) warmer than Stage 2. On a call for 3

rd

Stage cooling the lead unit economizer will continue to
operate as long as outdoor conditions are acceptable,
and the compressor will operate on compressor Stage
1 partial capacity. If outdoor conditions are not
acceptable for free cooling the lead unit compressor
will automatically be operating on compressor Stage
1 partial capacity and will go to Stage 2 full capacity
operation.

th

cooling setpoint is 2F (default setting, user

4
selectable 2-3F) warmer than Stage 3. On a call for 4

th

Stage cooling the lag unit economizer will continue to
operate as long as outdoor conditions are acceptable,
and the compressor will operate on compressor Stage
1 partial capacity. If outdoor conditions are not
acceptable for free cooling the lag unit compressor
will automatically be operating on compressor Stage
1 partial capacity and will go to Stage 2 full capacity
operation.

COOLING OPERATING SEQUENCES
FOR NON-ALTERNATING LEAD/LEAD/
LAG/LAG CONFIGURATION

Note: Heat pumps cannot be operated in Non­Alternating Lead/Lead/Lag/Lag sequence. Selecting
Heat Pump = Yes will override a Non-Alternating
selection and force system to Alternating Lead/Lag/
Lead/Lag sequence.

1. 2-Stage Compressor Units No Economizer

st

stage1st stage cooling setpoint is the setting (SP)

1
input into the controller. Factory default is 77F
(25C). On a call for cooling the blower of the lead
unit will come on immediately (if not already on – See
Blower Operation), and the Stage 1 LED will blink for
10-seconds before going solid, at which time the lead
unit compressor will start in compressor Stage 1 partial
capacity operation.

2nd cooling setpoint is 4F (default setting, user
selectable 2-6F) warmer than Stage 1, at which time
the lead unit compressor will switch to compressor
Stage 2 full capacity.

rd

cooling setpoint is 2F (default setting, user

3
selectable 2-3F) warmer than Stage 2. On a call for 3
Stage cooling the blower of the lag unit will come on
immediately (if not already on – See Blower Operation),
and Stage 3 LED will blink for 10-seconds before going
solid, and then the lag unit compressor will start in
compressor Stage 1 partial capacity.

th

cooling setpoint is 2F (default setting, user

4
selectable 2-3F) warmer than Stage 3. On a call for
4th Stage cooling the Stage 4 LED comes on solid
(no delay), and the lag unit compressor will switch to
compressor Stage 2 full capacity operation.

2. 1-Stage Compressor Units with Older EIFM
Economizers

st

stage cooling setpoint is the setting (SP) input into

1
the controller. Factory default is 77F (25C). On a call
for cooling the blower of the lead unit will come on
immediately (if not already on – See Blower Operation),
and the Stage 1 LED will blink for 10-seconds before
going solid, at which time the lead unit Y1 cooling
output turns on. If the outdoor temperature and
humidity conditions are below the setpoint of the
economizer control the lead unit economizer will
operate instead of the compressor. If outdoor conditions
are not acceptable for free cooling the compressor will
automatically operate instead of the economizer.

nd

cooling setpoint is 4F (default setting, user

2
selectable 2-6F) warmer than Stage 1. On a call for 2
Stage cooling the lead unit Y2 cooling output turns on.
The lead unit economizer will close and the compressor
will operate. If the compressor is already running from

st

1

stage cooling call due to outdoor conditions being
outside of free cooling range no action occurs at 2
stage setpoint.

rd

cooling setpoint is 2F (default setting, user

3
selectable 2-3F) warmer than Stage 2. On a call for

rd

Stage cooling the blower of the lag unit is turned

3
on (if not already on – See Blower Operation), and
the Stage 3 LED will blink for 10-seconds before
going solid, and the lag unit economizer will operate
if the outdoor temperature and humidity conditions
are below the setpoint of the economizer control. If
outdoor conditions are not acceptable for free cooling
the compressor will automatically operate instead of the
economizer.

th

cooling setpoint is 2F (default setting, user

4
selectable 2-3F) warmer than Stage 3. On a call for 4th
Stage cooling the lag unit economizer will close and the
compressor will operate. If the compressor is already

rd

running from 3

stage cooling call due to outdoor
conditions being outside of free cooling range no action
occurs at 2

nd

stage setpoint.

rd

nd

nd

Manual 2100-614I
Page 11 of 43

3. 1-Stage Compressor Units with Newer
ECONWMT or WECOP Economizers (See Note A)

st

stage cooling setpoint is the setting (SP) input into

1
the controller. Factory default is 77F (25C). On a call
for cooling the blower of the lead unit will come on
immediately (if not already on – See Blower Operation),
and the Stage 1 LED will blink for 10-seconds before
going solid, at which time the lead unit Y1 cooling
output turns on. If the outdoor temperature and
humidity conditions are below the setpoint of the
economizer control the lead unit economizer will
operate instead of the compressor. If outdoor conditions
are not acceptable for free cooling the compressor will
automatically operate instead of the economizer.

nd

cooling setpoint is 4F (default setting, user

2
selectable 2-6F) warmer than Stage 1. On a call for

nd

stage cooling the lead unit Y2 cooling output turns

2
on. If the outdoor temperature and humidity conditions
are below the setpoint of the economizer control the
lead unit economizer will continue to operate, and the
compressor will operate. If the compressor is already
operating on 1
cooling range no action occurs at 2

rd

cooling setpoint is 2F (default setting, user

3
selectable 2-3F) warmer than Stage 2. On a call for 3

st

stage cooling because outside free

nd

cooling setpoint.

rd

Stage cooling the blower of the lag unit will come on
immediately (if not already on – See Blower Operation),
and the Stage 3 LED will blink for 10-seconds before
going solid, at which time the lag unit Y1 cooling
output turns on. The lag unit economizer will operate
if the outdoor temperature and humidity conditions
are below the setpoint of the economizer control. If
outdoor conditions are not acceptable for free cooling
the compressor will automatically operate instead of the
economizer.

th

cooling setpoint is 2F (default setting, user

4
selectable 2-3F) warmer than Stage 3. On a call for

th

Stage cooling the lag unit Y2 cooling output turns

4
on activating the lag unit compressor. If the outdoor
temperature and humidity conditions are below
the setpoint of the economizer control the lag unit
economizer will continue to operate. If the compressor

rd

is already operating on 3
outside free cooling range no action occurs at 4

stage cooling because

th

cooling setpoint.

4. 2-Stage Compressor Units with Older EIFM
Economizers

st

stage cooling setpoint is the setting (SP) input into

1
the controller. Factory default is 77F (25C). On a call
for cooling the blower of the lead unit will come on
immediately (if not already on – See Blower Operation),
and the Stage 1 LED will blink for 10-seconds before
going solid, at which time the lead unit Y1 cooling
output turns on. If the outdoor temperature and
humidity conditions are below the setpoint of the
economizer control the lead unit economizer will

operate instead of the compressor. If outdoor conditions
are not acceptable for free cooling the compressor will
automatically operate on compressor Stage 1 partial
capacity instead of the economizer.

nd

cooling setpoint is 4F (default setting, user

2
selectable 2-6F) warmer than Stage 1. On a call for 2

nd

stage cooling the lead unit Y2 cooling output turns on,
at which time the lead unit compressor will operate on
compressor Stage 2 full capacity. If the compressor is
already operating on Stage 1 partial capacity because
outside free cooling range the compressor will switch to
compressor Stage 2 full capacity.

rd

cooling setpoint is 2F (default setting, user

3
selectable 2-3F) warmer than Stage 2. On a call for 3

rd

Stage cooling the blower of the lag unit will come on
immediately (if not already on – See Blower Operation),
and the Stage 3 LED will blink for 10-seconds before
going solid. The lag unit economizer will operate if the
outdoor temperature and humidity conditions are below
the setpoint of the economizer control. If outdoor
conditions are not acceptable for free cooling the
compressor will automatically operate on compressor
Stage 1 partial capacity instead of the economizer.

th

cooling setpoint is 2F (default setting, user

4
selectable 2-3F) warmer than Stage 3. On a call for 4

th

Stage cooling the lag unit Y2 cooling output turns on,
at which time the lag unit compressor will operate on
compressor Stage 2 full capacity. If the compressor is
already operating on Stage 1 partial capacity because
outside free cooling range the compressor will switch to
compressor Stage 2 full capacity.

5. 2-Stage Compressor Units with Newer
ECONWMT or WECOP Economizers (See Note A)

st

stage cooling setpoint is the setting (SP) input into

1
the controller. Factory default is 77F (25C). On a call
for cooling the blower of the lead unit will come on
immediately (if not already on – See Blower Operation),
and the Stage 1 LED will blink for 10-seconds before
going solid, at which time the lead unit Y1 cooling
output turns on. If the outdoor temperature and
humidity conditions are below the setpoint of the
economizer control the lead unit economizer will
operate instead of the compressor. If outdoor conditions
are not acceptable for free cooling the compressor will
automatically operate on compressor Stage 1 partial
capacity instead of the economizer.

nd

cooling setpoint is 4F (default setting, user

2
selectable 2-6F) warmer than Stage 1. On a call for

nd

stage cooling the lead unit Y2 cooling output turns

2
on. If the outdoor temperature and humidity conditions
are below the setpoint of the economizer control the
lead unit economizer will continue to operate, and the
compressor will operate on compressor Stage 1 partial
capacity. If the compressor is already operating on
Stage 1 partial capacity because outside free cooling

Manual 2100-614I
Page 12 of 43

range the compressor will switch to compressor Stage 2
full capacity.

rd

cooling setpoint is 2F (default setting, user

3
selectable 2-3F) warmer than Stage 2. On a call for 3

rd

Stage cooling the blower of the lag unit will come on
immediately (if not already on – See Blower Operation),
and the Stage 3 LED will blink for 10-seconds before
going solid, at which time the lag unit Y1 cooling
output turns on. The lag unit economizer will operate
if the outdoor temperature and humidity conditions
are below the setpoint of the economizer control.
If outdoor conditions are not acceptable for free
cooling the compressor will automatically operate on
compressor Stage 1 partial capacity instead of the
economizer.

th

cooling setpoint is 2F (default setting, user

4
selectable 2-3F) warmer than Stage 3. On a call for 4

th

Stage cooling the lag unit Y2 cooling output turns on
activating the compressor. If the outdoor temperature
and humidity conditions are below the setpoint of
the economizer control the lag unit economizer will
continue to operate, and the compressor will operate on
compressor Stage 2 full capacity. If the compressor is
already operating on Stage 1 partial capacity because
outside free cooling range the compressor will switch to
compressor Stage 2 full capacity.

Note A: Economizers in ECONWMT or WECOP Series
are available with either “T” temperature only outdoor
sensor or “E” enthalpy (temperature and humidity)
outdoor sensor. The “T” versions will have a fixed (but
selectable) outdoor temperature decision whereas on
the “E” versions the outdoor temperature decision
will float based on outdoor humidity and the selected
Enthalpy curve in the economizer control module.

HEATING SEQUENCE OF OPERATION

Note: All heating sequences for air conditioners with
electric heat or heat pumps will automatically operate
in Alternating Lead/Lag/Lead/Lag sequence even if
controller is set to Non-Alternating for cooling with or
without economizers.

1. Air Conditioners with Electric Heat

st

stage heating setpoint is the dead-band (db) below

1

st

stage cooling setpoint (the SP entered into the

the 1
program). The dead-band is adjustable from 2-40F, and
factory default is 17F.

nd

stage heating setpoint will operate at same inter-

2
stage differential as set for cooling mode.

2. Heat Pumps with Electric Heat

When the MC4002 controller is configured for heat
pump installations the 2
units 1 and 2 are redefined and used to control the
reversing valves, and which are energized in heating
mode.

st

stage heating setpoint is the dead-band (db) below

1

st

stage cooling setpoint (the SP entered into the

the 1
program). The dead-band is adjustable from 2-40F, and
factory default is 17F.

st

-stage heating consists of lead unit blower coming

1
on (if not already on – See Blower Operation), and
reversing valve being energized. The Stage 1 heating
LED will blink for 10-seconds, at which time the
compressor turns on.

nd

heating setpoint is 4F (default setting, user

2
selectable 2-6F) cooler than Stage 1. On a call for 2
Stage heating the blower of the lag unit is turned on (if
not already on – See Blower Operation), the reversing
valve is energized, and the Stage 2 LED will blink
for 10-seconds before going solid, at which time the
compressor will start.

rd

-stage heating will be the electric heater, if so

3
equipped, in the lead unit. Stage 3 heating LED comes
on solid with no blinking.

th

-stage heating will be the electric heater, if so

4
equipped, in the lag unit. Stage 4 heating LED comes
on solid with no blinking.

nd

-stage (Y2) outputs for both

nd

Manual 2100-614I
Page 13 of 43