Trane ACONT900AC43UA, TCONT900AC43UA, Charge Assist Service Manual

Air Conditioning Procedures

Service Guide

Communicating Residential

Comfort Systems

A Comprehensive Reference for Service of Communicating

Residential Air Conditioning, Heat Pump & Gas Furnace Systems

First Edition

© 2010 Trane Inc.
All rights reserved. No part of this book
may be reproduced, in any form or by
any means, without permission in
writing from the publisher.

Produced and printed in the USA

1.0

We appreciate your feedback.....

We value your opinion. If you feel this service guide can be improved in some way, please
give us your thoughts. Simply email your opinion to [e-mail]. You may also
write in the space below , tear out this p age and mail it to:

Trane Company

Attn: Loran Dailey

6200 Troup Hwy.

Tyler , TX 75707

Comments

Air Conditioning Procedures

Name:
Address:
Email:
Phone#

Pub# 034-3457-01

We appreciate your feedback.....

We value your opinion. If you feel this service guide can be improved in some way, please
give us your thoughts. Simply email your opinion to [e-mail]. You may also
write in the space below , tear out this p age and mail it to:

Trane Company

Attn: Loran Dailey

6200 Troup Hwy.

Tyler , TX 75707

Comments

Air Conditioning Procedures

Name:
Address:
Email:
Phone#

Pub# 034-3457-01

WARNING

!

Cautions & Warnings

Throughout this manual there are procedures where voltage may be
present and gas or refrigerant system checks may be required. Read all
cautions and warnings on this page before proceeding.

W ARNING

!

SAFETY HAZARD

THIS INFORMATION IS INTENDED FOR USE BY
INDIVIDUALS POSSESSING ADEQUA TE BACKGROUNDS
OF ELECTRICAL AND MECHANICAL EXPERIENCE. ANY
ATTEMPT T O REPAIR A CENTRAL AIR CONDITIONING
PRODUCT MA Y RESUL T IN PERSONAL INJURY AND OR
PROPERTY DAMAGE. THE MANUFACTURER OR SELLER
CANNOT BE RESPONSIBLE FOR THE INTERPRET ATION
OF THIS INFORMATION, NOR CAN IT ASSUME ANY
LIABILITY IN CONNECTION WITH ITS USE.

W ARNING

!

FIRE OR EXPLOSION HAZARD

FAILURE TO FOLLOW THE SAFETY WARNINGS EXACTLY
COULD RESUL T IN SERIOUS PERSONAL INJURY , PROPERTY
DAMAGE, OR DEATH. IMPROPER SER VICING COULD RESULT
IN DANGEROUS OPERA TION, SERIOUS PERSONAL INJURY ,
PROPERTY DAMAGE, OR DEA TH.

W ARNING

!

SERVICE PROCEDURES HAZARD

BODILY INJURY CAN RESULT FROM HIGH VOLTAGE
ELECTRICAL COMPONENTS, FAST MOVING FANS, AND
COMBUSTIBLE GAS. FOR PROTECTION FROM THESE
INHERENT HAZARDS DURING INSTALLATION AND
SERVICING, THE ELECTRICAL SUPPLY MUST BE
DISCONNECTED AND THE MAIN GAS VALVE MUST BE
TURNED OFF . IF OPERATING CHECKS MUST BE PERFORMED
WITH THE UNIT OPERATING, IT IS THE TECHNICIAN’S
RESPONSIBILITY TO RECOGNIZE THESE HAZARDS AND
PROCEED SAFEL Y .

W ARNING

!

V oltage Hazard

Disconnect power to the unit before removing the
blower door. Allow a minimum of 10 seconds for IFC
power supply to discharge to 0 volts. Failure to follow
this warning could result in property damage, personal

injury or death.

W ARNING

!

CARBON MONOXIDE POISONING HAZARD

FAILURE TO FOLLOW THE SER VICE AND/ OR PERIODIC
MAINTENANCE INSTRUCTIONS FOR THE FURNACE AND
VENTING SYSTEM, COULD RESUL T IN CARBON MONOXIDE
POISONING OR DEATH.

W ARNING

!

FIRE OR EXPLOSION HAZARD

SHOULD OVERHEATING OCCUR, OR THE GAS SUPPL Y FAIL
TO SHUT OFF, SHUT OFF THE GAS VALVE TO THE UNIT
BEFORE SHUTTING OFF THE ELECTRICAL SUPPL Y . FAILURE
TO FOLLOW THIS WARNING COULD RESUL T IN PROPERTY
DAMAGE, PERSONAL INJURY , OR DEA TH.

CAUTION

!

Safety Hazard

Sharp Edge Hazard
Be careful of sharp edges on equipment or any cuts
made on sheet metal while installing or servicing.
Personal injury may result.

Where there is no complete return duct system, the
return connection must be run full size from the furnace
to a location outside the utility room, basement, attic,
or crawl space.

Do NOT install return air through the back of the furnace
cabinet.

Do NOT install return air through the side of the furnace cabinet
on horizontal applications.

NOTE: Minimum return air temperature is 55°F.

CAUTION

!

CONTAINS REFRIGERANT!

SYSTEM CONT AINS OIL AND REFRIGERANT UNDER HIGH
PRESSURE. RECOVER REFRIGERANT TO RELIEVE
PRESSURE BEFORE OPENING SYSTEM.
Failure to follow proper procedures can result in
personal illness or injury or severe equipment damage.

CAUTION

!

LABELING WIRES!

LABEL ALL WIRES PRIOR TO DISCONNECTION WHEN
SERVICING CONTROLS. WIRING ERRORS CAN CAUSE
IMPROPER AND DANGEROUS OPERA TION. VERIFY PROPER
OPERATION AFTER SERVICING .

CAUTION

!

BURN HAZARD

DO NOT TOUCH IGNITER. IT IS EXTREMEL Y HOT .

A 1

Cautions & Warnings

A 2

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(A/T)CONT900AC43UA Installer Guide

Communicating Controller

Section A

Introduction........................................................................................................................................ 3

Product specifications ................................................................................................................... 3

Installation.......................................................................................................................................... 3

When installing this product .......................................................................................................... 3

Location......................................................................................................................................... 4

Selecting Comfort Control location ............................................................................................... 4

Sub-base installation ..................................................................................................................... 4

Wiring............................................................................................................................................ 5

Mounting Comfort Control on sub-base......................................................................................... 6

Initial power-up .................................................................................................................................. 6

Power-up sequence....................................................................................................................... 6

Discovery mode ............................................................................................................................ 6

Communicating indoor unit - Communicating outdoor unit ........................................................... 7

Communicating indoor unit - Single stage cooling unit ................................................................. 7

Adjusting real time clock .................................................................................................................. 7

Setting calendar and time ............................................................................................................. 7

Installer setup (ISU) ........................................................................................................................... 8

Entering installer setup.................................................................................................................. 8

Operation: Using the Comfort Control .......................................................................................... 18

System and fan settings .............................................................................................................. 18

Fan settings................................................................................................................................. 18

LED indication ............................................................................................................................. 18

Filter indication............................................................................................................................ 18

Pre-programmed ......................................................................................................................... 18

Alert code numbers ..................................................................................................................... 18

Equipment damage hazard. Minimum compressor off-time is bypassed during installer

System test ..................................................................................................................................19

System checkout ............................................................................................................................. 19

Installer system test..................................................................................................................... 19

Advanced features........................................................................................................................... 19

Adjustable continuous air flow..................................................................................................... 19

Control response rate .................................................................................................................. 20

Cycle rate .................................................................................................................................... 20

Auto changeover ......................................................................................................................... 20

C - A 1

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Setpoint deadband ...................................................................................................................... 21

Backlit display ............................................................................................................................. 21

Filter reminders ........................................................................................................................... 21

Fan selections ............................................................................................................................. 21

Screen locked.............................................................................................................................. 21

Installer system tests................................................................................................................... 21

Default factory settings................................................................................................................ 21

Wait indicator .............................................................................................................................. 22

Calibrate indoor temperature....................................................................................................... 22

TCONT900AC43UA Installer’s Guide

Calibrate outdoor temperature .................................................................................................... 22

Outdoor temperature sensor ....................................................................................................... 22

Humidification.................................................................................................................................. 22

Indoor humidification control ....................................................................................................... 22

Frost control ................................................................................................................................ 22

Dehumidification ............................................................................................................................. 22

Integrated temperature and humidity control (ITHC)................................................................... 22

Droop ............................................................................................................................................23

Comfort-R™ delay .........................................................................................................................23

Dehumidification airflow .................................................................................................................23

Proprietary humidity control...........................................................................................................23

Special heat pump features ............................................................................................................ 23

Auxiliary heat lockout temperature..............................................................................................23

Compressor heat lockout temperature ........................................................................................ 23

Operation in heat mode............................................................................................................... 24

Defrost heater balance point control ........................................................................................... 24

Operation in emergency heat mode ............................................................................................ 24

Heat pump with fossil fuel heat (dual fuel) and outdoor temperature sensor .............................. 24

Troubleshooting guide ................................................................................................................... 25

C - A 2

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(A/T)CONT900AC43UA Installer Guide

Introduction

The (A/T)CONT900AC43UA is a communicating pro­grammable Comfort Control (See Table 1) that sup­ports single-stage or multi-stage heat/cool and heat
pump applications. It is a wall mounted, low voltage
(24V AC) communicating Comfort Control with backlit
LCD and a touch screen display . Room temperature
is maintained by controlling the operation of heating,
cooling, heat pump, and dual fuel systems via digital,
two-way communications. The Comfort Control will
communicate with and identify all ComfortLink™ II com­ponents in the system. It is easily manually config­ured via the user friendly Installer Setup menu. The
Comfort Control feature includes separate heating and
cooling setpoints, selectable auto or manual
changeover, menu driven 7-day programming, adjust­able filter reminders, and outdoor temperature sens­ing. Setup selections and diagnostics are stored in­definitely in the Comfort Control’s nonvolatile memory ,
eliminating the need for battery backup.

Product specifications

Power source: 18-30 VAC, Class II, 50/60 Hz
Storage range: -30°F to 150°F, 5% to 90% RH non­condensing
Operating temperature range: 0°F to 120°F, 5% to
90% RH non-condensing

System mode: Heat, Cool, Auto, Emergency Heat,
and Off
Fan mode: On, Auto and Circ
Cooling setpoint temperature range: 60°F to 99°F,
1°F resolution
Heating setpoint temperature range: 50°F to 90°F,
1°F resolution
Indoor temperature display range: 40°F to 99°F ,
Outdoor temperature display range: -40°F to 127°F
Indoor humidity display range: 0% to 99%, 1% reso­lution
Minimum cycle off time delay: Compressor, 5 min­utes. Heat, 0 minutes.

The comfort control contains a Lithium battery which
may contain Perchlorate material.
Due to State Law in California, the following st atement
is required:

Perchlorate Material-special handling may apply . See

www.dtsc.ca.gov/hazardouswaste/perchlorate

Installation

When installing this product

Step 1

Read these instructions carefully. Failure to follow
these instructions may damage the product or cause
a hazardous condition.

T able 1

C - A 3

(A/T)CONT900AC43UA Installer Guide

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Step 2

Check the ratings given in the instructions and on
the product to make sure the product is suitable for
your application.

Step 3

Installer must be a trained, experienced service tech­nician.

TCONT900AC43UA Installer’s Guide

Step 4

After completing installation, use these instructions
to check out the product operation.

WARNING

Voltage Hazard. Can cause electrical shock or
equipment damage. Disconnect power before
beginning instructions.

Location

Install the Comfort Control about five feet (1.5m)
above the floor in an area with good circulation at
average temperature (See Figure 1.)

Figure 1

Selecting Comfort Control location

Do not install the Comfort Control where it can be
affected by

• Drafts or dead spots behind doors and in
corners.

• Hot or cold air from ducts.

• Radiant heat from sun or appliances.

• Concealed pipes and chimneys.

• Unheated (uncooled) areas such as an outside
wall behind the Comfort Control.

Sub-base installation

The Comfort Control can be mounted horizontally
on the wall or on a two inch by four inch wiring box.
Position sub-base horizontally on the wall or on a two
inch by four inch wiring box.

Step 1

Turn OFF all power to heating and cooling equip­ment.

Step 2

If an existing Comfort Control is being replaced:

a.)Remove existing Comfort Control from the wall.
b.)Disconnect wires from existing control, one at

a time. Be careful not to allow wires to fall back
into wall.

c.) As each wire is disconnected, record wire color

and terminal marking.

d.)Discard or recycle old Comfort Control.

C - A 4

Step 3

Separate the Comfort Control from the sub-base to
expose mounting holes.

Step 4

Position and level the sub-base wallplate (for appear­ance only.) The Comfort Control functions properly
even when not level.

Communicating Programmable 3-Wire Hookup

4 Heat/3 Cool/ Heat Pump

(A/T)CONT900AC43UA Installer Guide

Step 5

Use a pencil to mark the mounting holes.

Step 6

Remove the sub-base from the wall and drill two 3/
16” holes in the wall (if drywall) as marked.
For firmer material such as plaster, drill two 7/32” holes.
Gently tap anchors (provided) into the drilled holes until
flush with the wall.

Step 7

Position the sub-base over the holes, pulling the wires
through the wiring opening.

Step 8

Insert the mounting screws in the holes and tighten.

Wiring

All wiring must comply with local electrical codes and
ordinances. See Figures 2 and 3 wiring diagrams
for specific equipment applications. Refer to Table
2 for terminal designations.

Figure 2

Figure 3

Field wiring diagram, Communicating indoor unit - Single stage cooling unit

T able 2

Field wiring diagram, Communicating indoor unit - Communicating outdoor unit

WARNING

Voltage Hazard. Can cause electrical shock or
equipment damage. Disconnect power before
beginning instructions.

Note:

The maximum cable length for the entire Comfort Control com­municating system is 500 feet 18 AWG. The maximum dis­tance of any single cable from a transformer is 250 feet 18
AWG.

C - A 5

(A/T)CONT900AC43UA Installer Guide

Step 1

Loosen the terminal screws on the sub-base. Insert
wires into the terminal block next to the loosened
screw (See Figure 4.)

Communicating Programmable 3-Wire Hookup

4 Heat/3 Cool/ Heat Pump

Step 2

Push the Comfort Control straight onto the wallplate
(See Figure 4.)

Step 3

Perform installation of all other system equipment.

Figure 4

TCONT900AC43UA Installer’s Guide

Important: Use 18-gauge color-coded Comfort Control cable for proper
wiring. Shielded cable is not typically required. Keep this wiring at least
one foot away from large inductive loads such as Electronic Air Cleaners,
motors, line starters, lighting ballasts, and large distribution panels. Failure
to follow there wiring practices may introduce electrical interference (noise)
which can cause erratic system operation. All unused Comfort Control wire
to be grounded at indoor unit chassis ground only. Shielded cable may be
required if the above wiring guidelines cannot be met. Ground the shield
only to the system chassis.

Step 2

Securely tighten each terminal screw.

Step 3

Push excess wire back in the hole.

Step 4

Plug the hole in the wall with nonflammable insulation
to help prevent drafts from adversely affecting Comfort
Control operation.

Mounting Comfort Control on sub-base

Step 1

Align the terminal screw block with the pins on the
back of the Comfort Control.

C - A 6

Step 4

Turn ON power to the heating and cooling equip­ment.

Initial power-up

Power-up sequence

The communicating Comfort Control will communicate
and identify all communicating components in the sys­tem.

Discovery mode

Discovery mode begins when the communicating Com­fort Control is first installed and power is connected.
For communicating equipment, the Comfort Control
automatically configures the equipment type, number
of stages, cycle rates for each stage and compressor
stage ratios based on the information it received dur­ing Discovery mode.

While in Discovery mode, the LED indicator located
in the upper right corner of the Comfort Control will
be illuminated.

All discovered values will be saved into memory. If
a communicating device goes missing (Err 89) or
changes in value (Err 126) the error will be broad­cast to the Comfort Control screen (restoring com­munications will clear this error or see ISU 0706 to
reset the system configuration.)

The communicating Comfort Control can be reset
(ISU 0710) to factory default settings.

Note: ISU 0706 Will force a reinitialization without af­fecting presets. ISU 0710 will reset everything includ­ing custom programs and presets.

Communicating Programmable 3-Wire Hookup

4 Heat/3 Cool/ Heat Pump

If no equipment is connected during the Auto-Discov­ery process, the system mode will be stuck at “OFF”
and no equipment will run.

T o change the default/discovery settings, enter the in­staller Setup menu (See Table 4, Pages 9-17) and
select the desired item.

Only ISU settings with an “E” will be Auto-Discovered.
Manually changing an ISU setting to an option other
than “E” disables Discovery mode for that ISU setting.

See Table 3 for default cycle rate settings.

T able 3

(A/T)CONT900AC43UA Installer Guide

Adjusting real time clock

Setting calendar and time

Locate and remove the tab labeled “Remove” in the
lower left corner of the Comfort Control back. The
tab must be removed to activate the real time clock.
(See Figure 5.)

Figure 5

Communicating indoor unit - Communicating
outdoor unit

For a fully communicating system, the communicat­ing Comfort Control will automatically configure the
indoor and outdoor equipment configuration and cycle
rates for each stage (See Figure 2.)

Communicating indoor unit - Single stage
cooling unit

For a partially communicating system, the commu­nicating Comfort Control will automatically config­ure the indoor equipment configuration and cycle
rates for each stage (See Figure 3.)

The outdoor equipment configuration will default to
a single stage cooling unit.

If the system is not powered, the real time clock bat­tery life is approximately 20 weeks.

The Comfort Control is designed to automatically
keep the current time and day in memory for up to
ten years under normal use once calendar is set.
When the Comfort Control is powered, the display is
ready for the calendar date to be entered (See Fig­ure 6, next page)

Note: Clock accuracy is +/- 1 minute per month

C - A 7

(A/T)CONT900AC43UA Installer Guide

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Figure 6

TCONT900AC43UA Installer’s Guide

Installer setup (ISU)

The Comfort Control works with many different sys­tem types. The installer can use the Installer Setup
menu to change factory settings to customize instal­lations (See T able 4.)

Figure 7

Step 4

Release the two blank keys when the screen on the
Comfort Control matches the screen in Figure 8 (See
Figure 8.)

Figure 8

Entering installer setup

Follow these steps to enter the Installer Setup:

Step 1

Be sure the Comfort Control is powered. If neces­sary , press the Done key to return to the home screen.

Step 2

Press and release the system key.

Step 3

Press and hold the two blank keys on either side of
the center key for approximately five seconds until
screen changes (See Figure 7.)

C - A 8

Step 5

See Figure 8 to review how the Comfort Control keys
are used during Installer Setup (See Table 4, Pages
9-17) for the Installer Setup numbers and settings.

Communicating Programmable 3-Wire Hookup

4 Heat/3 Cool/ Heat Pump

Step 6

Press the Done key to exit the Installer Setup.

Note:

Manually changing an ISU setting to an option other than “E”
disables Discovery mode for that ISU setting. If power is lost,
all custom settings are retained in the memory .

T able 4. Inst aller Setup Menu.

(A/T)CONT900AC43UA Installer Guide

C - A 9

(A/T)CONT900AC43UA Installer Guide

Table 4. Installer Setup Menu Continued.

TCONT900AC43UA Installer’s Guide

Communicating Programmable 3-Wire Hookup

No humidity option available if 3 is
selected

4 Heat/3 Cool/ Heat Pump

Note: If single stage is configured, ODU will run Low Stage,
but ID airflow ill be 100%. If 3-Three Stage is configured,
there will be an Err 89 on stat but unit will run.

For 3 stage furnace:
Option 1 = High stage heat only
Option 2 = Medium and high stage heat only

For modulating furnace:
Option 1 = High stage heat
Option 2= Modulating
Option 3 = 40% or 100% - No modulation

Note: If anything else is configured, other than
“E1”, then the blower will not run in cooling with
a furnace but continuous fan and heat will op­erate blower okay/

Note: Auto discovered low stage airflow for 20
SEER:
2 Ton = 50%
3 Ton = 55%
4 Ton = 50%
5 Ton = 65%

C - A 10

Communicating Programmable 3-Wire Hookup

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Table 4. Installer Setup Menu Continued.

(A/T)CONT900AC43UA Installer Guide

Note: E1 = Auto discovered w/com ODU
E0 = Auto discovered w/o com ODU

C - A 11

(A/T)CONT900AC43UA Installer Guide

Table 4. Installer Setup Menu Continued.

TCONT900AC43UA Installer’s Guide

HP with EH = 0 (no lockout)
Dual Fuel = 40 degrees default
(Range is 5 - 60)

Communicating Programmable 3-Wire Hookup

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Note: Y2 counter only with Phase 2 product (serial date
code 0904) if heat demand is satisfied by Y2 - reset timer

Note: “0” is not an option with Dual Fuel (must
have a lockout temp configured)

C - A 12

Dual Fuel = 50 degrees default
Must have option 2 selected in
ISU0350.
(Range is 45-65 with 40 degree de­fault is selected in ISU0350). (A 5 de­gree deadband is enforced between
comp lockout and aux heat lockout)

Note: For phase 2 factory
setting = 0 - disabled.
(phase 2 = serial data code 0904)

Note: Watch for cool air complaints during de­frost if aux heat lockout is configured. Also be
aware of ISU0361, 362 and 363.

Communicating Programmable 3-Wire Hookup

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Table 4. Installer Setup Menu Continued.

Not shown if ODU is 2-stage HP and
3 stages of heat are present

(A/T)CONT900AC43UA Installer Guide

Note 1: RH gives 10-60% range selection on “MORE” screen
Note 2: Dewpoint control gives 0-10 range selection on “MORE”
screen. Either screen shows RH% on “MORE” screen

Option 1 = continuous fan speed (default = 50% cooling CFM
Note: Fan runs for 2 minutes after humidifier demand ends

Phase 2 (serial date code 0904) makes
this option available in USU

ISU0380 must = 1 for this ISU

If “0” is selected, RH% is no
longer displayed on the “MORE”
screen.

Deadband restricted to 5-9 degrees with
ITHC enabled. See ISU0310

C - A 13

(A/T)CONT900AC43UA Installer Guide

Table 4. Installer Setup Menu Continued.

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Only shown if ISU0380 is set to 1 or 4

TCONT900AC43UA Installer’s Guide

C - A 14

Communicating Programmable 3-Wire Hookup

4 Heat/3 Cool/ Heat Pump

Table 4. Installer Setup Menu Continued.

(A/T)CONT900AC43UA Installer Guide

Phase 2 changes range from 50-90

C - A 15

(A/T)CONT900AC43UA Installer Guide

Table 4. Installer Setup Menu Continued.

Phase 1 = 120 seconds
Phase 2 = 0 seconds

Phase 1 = 0 seconds
Phase 2 = 90 seconds

Phase 1 = 0 - disabled
Phase 2 = 5 - 1.5 min@100%

TCONT900AC43UA Installer’s Guide

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C - A 16

Communicating Programmable 3-Wire Hookup

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Table 4. Installer Setup Menu Continued.

(A/T)CONT900AC43UA Installer Guide

C - A 17

(A/T)CONT900AC43UA Installer Guide

Communicating Programmable 3-Wire Hookup

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Operation: Using the Comfort Control

System and fan settings

The system default setting is Heat, unless no Heat
stage is discovered/configured. The fan default is
Auto.

System settings

TCONT900AC43UA Installer’s Guide

Heat: Controls heating system.
Off: Heating and cooling are off.
Cool: Controls cooling system.
Auto: Automatically changes between heating and
cooling systems, depending on indoor temperature
(See Installer Setup section.)
Em. Heat: Compressor is locked out and auxiliary
heat cycles to maintain temperature (used only for
heat pump systems with backup heat.) Maximum
allowable emergency heat stages is three.

Fan settings

Pressing the fan key selects whether the indoor fan
motor runs in the On, Automatic, or Circulation mode.
The fan setting can be programmed into the Com­fort Control schedule for each period (wake, leave,
return, sleep.)

On: Fan runs continuously.
Auto: Fan run is automatically following the fan sched­ule.
Circ: Circulation control will provide a variable circu­lation determined by the Adaptive Intelligent Circu­lation (AIC) algorithm running the fan between 20%
and 60% of the time.

• It indicates that the Comfort Control is in Dis-

covery mode.

Filter indication

The Comfort Control can track up to two filter timers
by total fan run time or calendar days. This feature
can be used to tell the homeowner when to replace
the furnace filter or clean the Air Cleaner cells:

Select filter timer reset time:
Total fan run time: The number of run time days for

the filter timer to count down from: 0, 10, 30, 60, 90,
120, 180, 270, or 365 days (one run time day repre­sents 24 hours or continuous fan/system run time.)

Calendar days: The number of days for the filter timer
to count down from: 0, 30, 60, 90, 120, 180, or 365
days. To activate this feature, select a value other
than 0 (disabled.)

Pre-programmed

Table 5 shows the Energy Star default program set­tings. See owner’s guide for complete instructions
on changing the program (See Table 5.)

T able 5

T able 5. Energy S tar Default Program Settings.

LED indication

An LED indicator is located in the upper right corner
of the Comfort Control. It is only visible when illumi­nated.

• It indicates that there is an Alert.

C - A 18

Alert code numbers

The Comfort Control can receive Alert codes from
any communicating equipment’s buss. The Comfort
Control will illuminate the Red “Service” LED and

Communicating Programmable 3-Wire Hookup

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(A/T)CONT900AC43UA Installer Guide

toggle between the main screen and a screen show­ing the Alert code number . When multiple Alert codes
exist simultaneously, the display will cycle through
each code (showing a maximum of the five most re­cent Alert s) and return to the main screen.

Equipment damage hazard. Minimum
compressor off-time is bypassed during Installer
System T est.

Avoid cycling compressor quickly . Observe compres­sor protection period.

System checkout

Installer system test

The Installer System Test mode is used to test the
Comfort Control operation with HVAC equipment
(See Table 6, Pages 19-20.) System configuration
determines which tests are available and the num­ber of stages shown. While in System Test mode,
the minimum off time is bypassed.

The Installer Test is part of the Installer Setup op­tions. Enter Installer Setup screen and press the
Down arrow key for quick access to the test
selection(s).

• Changing tests will turn equipment off.

• Entering Installer Setup will turn equipment off.

• Charge Assist™ mode not available during
Installer System Tests.

• Test modes times out after five minutes.

Advanced features

Adjustable continuous air flow

The Continuous Fan air flow is user adjustable from
25% to 100% in 5% increments either by entering
the User Setup menu or the Installer Setup menu
(See Table 4, ISU Number 0186, Page 10.)

• Continuous fan mode during cooling operation
may not be appropriate in humid climates. If the
indoor air exceeds 60% relative humidity or sim­ply feels uncomfortably humid, it is

T able 6

T able 6. Inst aller System Tests.

C - A 19

(A/T)CONT900AC43UA Installer Guide

T able 6. Inst aller System T ests Continued.

TCONT900AC43UA Installer’s Guide

Communicating Programmable 3-Wire Hookup

4 Heat/3 Cool/ Heat Pump

recommended that the fan only be used in the
AUTO mode.

Control response rate

A set of more/less aggressive Proportional-Integral
control constants can be chosen to increase/decrease
the responsiveness of the temperature control per­formance. Choosing a more aggressive rate may
cause overshooting. Furthermore, selecting a less
aggressive rate may result in undershooting.

Cycle rate

Cycle rate is the selected number of system cycles
per hour at 50% load. If the cycle rate were set to 3,

C - A 20

each ON/OFF cycle would be 20 minutes long when
operating at 50% load. The total ON and/or OFF
times depends on the actual indoor space load. A
shorter cycle rate may be desired for Heating mode
to maintain tighter control to indoor setpoint. A longer
cycle rate may be desired for Cooling mode to allow
the system to remove moisture from the air and im­prove indoor comfort.

Auto changeover

When the system mode is set to Auto, the control
automatically switches between heating and cooling
modes to maintain the desired comfort level.

Communicating Programmable 3-Wire Hookup

4 Heat/3 Cool/ Heat Pump

(A/T)CONT900AC43UA Installer Guide

Setpoint deadband

The number of degrees separating Heating and Cool­ing setpoints is user adjustable from two to nine de­grees. When the control is set to Auto, and the cool­ing setpoint is changed to a cooler setpoint, the heat­ing setpoint will also change to maintain the selected
deadband. The same action occurs when the Heat­ing setpoint is changed to a warmer temperature.

The deadband is restricted to a range of five to nine
degrees if ISU 0380 is set to Integrated Temperature
and Humidity Control (ITHC.)

Backlit display

When continuous backlight is disabled, the liquid
crystal display will illuminate only when a touchscreen
key is pressed to improve visibility. The backlight
stays on for 45 seconds after the last touchscreen
key press. When continuous backlight is enabled,
the liquid crystal display will remain illuminated con­tinuously. The display will dim to half brightness 45
seconds after the last touchscreen key press.

Filter reminders

The Comfort Control can track up to two filter timers
by total fan run time or calendar days. When the
preset timer(s) has expired to remind the homeowner
that it is time to change the filter(s), “Change” then
“Filter” will automatically flash. To reset either filter
timer, simply press the More key to access the filter
timer value and then press the Reset key . Once the
timer has been reset, the filter timer value can be
viewed at any time by simply pressing the More key
until the filter timer is displayed on the screen.

Both the filter timers are auto discoverable ISU set­tings. If no communicating filtering device has been
discovered, the auto discovered value will default to
zero. T o enable one or both timers, change ISU 0500
and/or ISU 0501 to a value other than zero.

Fan selections

Pressing the Fan key selects whether the indoor fan
motor runs in the On, Automatic, or Circulation mode.
In On mode, the fan motor runs continuously. The
fan automatically follows the fan schedule in Auto­matic mode. Circulation control will provide a vari­able circulation determined by the Adaptive Intelli­gent Circulation (AIC) algorithm running the fan be­tween 20% and 60% of the time. Each scheduled
period (wake, leave, return, sleep) can be pro­grammed with a specific fan setting (on, automatic,
or circulation.)

Screen locked

Locking the control’s touchscreen keys can help pre­vent unwanted tampering with or changing of control
settings. The Comfort Control can either be fully
locked or partially locked. Both options continuously
display “Screen Locked” on the screen. Changing
ISU number 0670 to zero will unlock the keys and
“Screen Locked” will disappear.

Installer system tests

The built-in Installer System Test mode allows the
serviceperson to quickly and easily test the Comfort
Control’s operation with HV AC equipment and makes
diagnostic procedures a snap. System configura­tion determines which tests are available and the
corresponding number of stages shown (See Table
6, Tests 1-6 for details.)

Default factory settings

The Comfort Control is shipped with a set of factory
default settings. The factory default settings can be
restored at any time using the Installer Setup menu
(See Table 4, ISU number 0710, Page 17.)

Before you perform Auto-Discovery mode (ISU num­ber 0710), it is recommended that you record all your
user settings. All user settings choices will be reset

C - A 21

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Communicating Programmable 3-Wire Hookup

4 Heat/3 Cool/ Heat Pump

to factory defaults in Auto-Discovery mode.

Wait indicator

“Wait” will be displayed when the setpoint is changed
in the direction of calling for additional system ca­pacity or the outdoor unit is in Charge Assist™ mode.
“Wait” indicates system time delays are being en­forced, and the control is adjusting to the new set-

TCONT900AC43UA Installer’s Guide

ting.

Calibrate indoor temperature

This option allows calibration of the room tempera­ture sensor. The selected number is number of de­grees, plus or minus, which will be added to the ac­tual temperature. The number can range between
+3 and -3 degrees in one degree increments. Fac­tory default is zero. The adjusted value will be used
as the temperature for both display and control ac­tion.

Calibrate indoor humidity

This option allows calibration of the indoor humidity
sensor. The selected number is percent relative hu­midity , plus or minus, which can be added to the ac­tual indoor humidity . The number can range between
+5 and -5% in one percent increments. Factory de­fault is zero. The adjusted value will be used as the
humidity for both display and control action.

sor becomes unavailable, no outdoor value will be
displayed. The Comfort Control will not send an Alert.

Humidification

Indoor humification control

This feature helps to control the indoor humidity to the
user’s humidification setpoint using a humidifier. The
humidification setpoint can range between 10% and
60% in 5% increments. When enabled, the default
humidification setpoint is 50%.

Frost control

The Frost control requires an outdoor sensor and a
humidifier. The Comfort Control calculates the pos­sibility of condensation or frost forming by using the
outside temperature and inside temperature to de­termine the dewpoint. When the dewpoint could
cause frost or condensation, the humidification re­quest will not be honored.

The Frost control can be accessed by pressing the
More key until the Frost setting is displayed on the
screen. It has a value range of zero to ten, with zero
representing glass with poor insulation and ten rep­resenting glass with perfect insulation. If the factory
setting results in too much condensation or frost on
the windows, lower the setting. When the air seems
too dry, raise the setting.

Outdoor temperature sensor

For accuracy, the initial reading of the outdoor tem­perature sensor requires five minutes to stabilize.
See the Sensor Instructions for installation informa­tion.

If the device is using an outdoor sensor for control
and the outdoor temperature sensor becomes un­available, the display will show dashes “--” and gen­erate an Alert. If the device is not using an outdoor
sensor for control and the outdoor temperature sen-

C - A 22

Dehumidification

Integrated temperature and humidity control
(ITHC)

The dehumidification control helps to control the in­door humidity to the user’s dehumidification setpoint
by running the compressor. The dehumidification
setpoint can be accessed by pressing the More key
until the dehumidification setpoint is displayed on the
screen. The setpoint can range between 40% and
80% in 5% increments. When enabled, the default

Communicating Programmable 3-Wire Hookup

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(A/T)CONT900AC43UA Installer Guide

dehumidification setpoint is 50%. In extremely high
humidity conditions, the Comfort Control keeps the
compressor running for up to 3°F (-1.7°C) below the
temperature setpoint. It does this while trying to
achieve the desired dehumidification setpoint and bal­ancing that with the temperature setpoint. The maxi­mum allowable dehumidification droop can be selected
in ISU 0383.

Droop

Droop is a feature that cycles the compressor on to
improve indoor comfort by removing moisture from the
air. The Droop cycle is activated when the indoor hu­midity is above the user’s dehumidification setpoint.
When this function is active, the Comfort Control will
control temperature at 1°F or 2°F below the cooling
setpoint. The Droop cycle is deactivated when the
indoor humidity drops below the user’s dehumidifica­tion setpoint. If the indoor humidity sensor fails, the
droop logic will always be enabled while in cooling
mode.

Comfort-R™ delay

When the indoor humidity is above the user’s dehu­midification setpoint, Comfort-R™ delay will remove
humidity from the air by implementing a blower turn­on delay of 15 or 30 seconds to “pre-chill” the coil.
Comfort-R™ delay applies to non-variable speed in­door unit types only .

Dehumidification airflow

During any dehumidification control option, a lower
speed fan can be activated. The settings range from
80% to 100% in 5% increments (See Table 4, Inst aller
Setup number 0387, Page 14.) The default dehumidi­fication airflow is 100%.

Proprietary humidity control

When enabled, this feature will disable any blower off
delays and disable continuous fan mode when

the indoor humidity is above the dehumidification
setpoint. This will help reduce coil condensation from
being evaporated back into the air stream.

• This feature, ISU 0388, is not shown unless

some form of dehumidification control is
selected.

• Proprietary humidity control does not af-

fect the fan operation when the fan setting at
the Comfort Control is in Auto or Circ modes.

Special heat pump features

Auxiliary heat lockout temperature

When an outdoor temperature sensor has been dis­covered/enabled, none of the installed auxiliary heat
stages will turn on during heating operation above the
selected outdoor temperature. When the outdoor tem­perature is less than the auxiliary heat lockout tem­perature (ISU number 0360), the Comfort Control may
cycle the indoor heat on and off to satisfy the load.
During defrost, this outdoor temperature setting is ig­nored and the defrost heater balance point outdoor
temperature thresholds are used.

For dual fuel applications, if the heat pump fails to
maintain heat while the outdoor temperature is above
the auxiliary lockout temperature, the furnace will be
used until the setpoint is reached, at which time heat
pump operation will resume.

Compressor heat lockout temperature

When an outdoor temperature sensor has been dis­covered/enabled, only the installed auxiliary heat
stages will turn on during heat operation below the
selected outdoor temperature. When the outdoor tem­perature is greater than the compressor heat lockout
temperature (ISU number 0350), the heat pump at­tempts to satisfy the load. If the heat pump cannot
satisfy the load, the Comfort Control will transition to

C - A 23

(A/T)CONT900AC43UA Installer Guide

Communicating Programmable 3-Wire Hookup

4 Heat/3 Cool/ Heat Pump

auxiliary heat operation and will turn off the heat pump.
During defrost, this outdoor temperature setting is ig­nored and the defrost heater balance point outdoor
temperature thresholds are used.

There is a 5°F deadband between the Compressor
and auxiliary heat lockout temperatures.

Operation in heat mode

TCONT900AC43UA Installer’s Guide

When the outdoor temperature is below the com­pressor lockout temperature, only the auxiliary heat
operates. When the outdoor temperature is above
the auxiliary lockout temperature, only the compres­sor operates (See Figure 9.)

Table 9. Heat Pump Operation

Figure 9

with Lockout T emperature Set.

If the outdoor temperature sensor has not been dis­covered/enabled, the stage or combination of stages
to be used during defrost can be set in Installer Setup
number 0364.

Operation in emergency heat mode

When the Comfort Control is placed in Emergency
Heat mode, the compressor and auxiliary lockout
features are turned off. In the Emergency Heat mode,
the compressor is locked out and only the auxiliary
heat operates. The Comfort Control is capable of
controlling up to a maximum of three Emergency
Heat stages.

Heat pump with fossil fuel heat (dual fuel) and
outdoor temperature sensor

In this operation, there is no external fossil fuel kit
(dual fuel kit) installed; the Comfort Control controls
this function. During the transition between furnace
and heat pump operation, there is a minimum Com­fort Control time delay of 45 seconds between the
furnace turning off and the heat pump turning on and
zero seconds between the heat pump turning off and
the furnace turning on.

When the outdoor temperature is between the two tem­peratures, both the compressor and auxiliary heat
operate.

Defrost heater balance point control

When an outdoor temperature sensor has been dis­covered/enabled, a separate outdoor temperature
turn-on threshold can be set for each installer heater
stage during defrost in Installer Setup numbers 0361-

0363. If the balance point for a particular heater stage
is disabled, the heater stage will be used during ev­ery defrost cycle independent of the outdoor tem­perature.

If the outdoor sensor is no longer reporting, all avail­able heater stages will be used during defrost.

C - A 24

If the outdoor unit is missing or no longer reporting,
the control algorithm will revert back to a fossil fuel
only application.

If the heat pump fails to maintain heat while the out­door temperature is above the auxiliary lock out tem­perature, the furnace will be used until the setpoint is
reached, at which time heat pump operation will re­sume.

Step 1
Choose appropriate Compressor Lockout T empera­ture in Installer Setup number 0350.

Communicating Programmable 3-Wire Hookup

4 Heat/3 Cool/ Heat Pump

Step 2

If heat pump auxiliary lockout was selected, in Installer
Setup number 0345, choose appropriate Heat Pump
Auxiliary Lockout Temperature in Installer Setup
number 0360.

Step 3
Choose appropriate Defrost Balance Point T empera­tures in Installer Setup numbers 0361-0363.

Troubleshooting guide

Refer to Table 7, Pages 26-27 for troubleshooting in­formation.

(A/T)CONT900AC43UA Installer Guide

C - A 25

(A/T)CONT900AC43UA Installer Guide

Table 7. Troubleshooting Information.

TCONT900AC43UA Installer’s Guide

T able 7. T roubleshooting Information Continued.

Communicating Programmable 3-Wire Hookup

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C - A 26

Communicating Programmable 3-Wire Hookup

4 Heat/3 Cool/ Heat Pump

T able 7. T roubleshooting Information Continued.

(A/T)CONT900AC43UA Installer Guide

C - A 27

(A/T)CONT900AC43UA Installer Guide

TCONT900AC43UA Installer’s Guide

Communicating Programmable 3-Wire Hookup

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C - A 28

Air Conditioning and Heat Pump Procedures

Communicating Air Conditioning and Heat Pump Systems

Sequences of Operation......................................................................................... A

Control Boards........................................................................................................ B

EEV Tests ................................................................................................................ C

Sensor Tests ........................................................................................................... D

Sump Heater............................................................................................................ E

Outdoor Fan Motor...................................................................................................F

Refrigeration Cycle Problems................................................................................ G

Sequences Of Operation

Communicating Air Conditioning and Heat Pump Systems

Section A

16 SEER .............................................................................................................................................. 2

Air Conditioner and Heat Pump models ......................................................................................... 2

Charge Assist™ ............................................................................................................................ 4

Power Interrupt Delay .................................................................................................................... 4

Heat Pump Cooling Mode of Operation.......................................................................................... 4

Defrost Mode ................................................................................................................................. 4

Defrost initiation............................................................................................................................. 5

Defrost termination ........................................................................................................................ 5

20 SEER .............................................................................................................................................. 6

Air Conditioner and Heat Pump models ......................................................................................... 6

Charge Assist™ ............................................................................................................................ 8

Power Interrupt Delay .................................................................................................................... 8

Heat Pump Cooling Mode of Operation.......................................................................................... 8

Heat Pump Heating Mode of Operation.......................................................................................... 9

Defrost Mode ................................................................................................................................. 9

Defrost initiation from first stage heating cycle .............................................................................. 9

Defrost termination to first stage heating cycle.............................................................................. 9

Defrost initiation from second stage heating cycle........................................................................10

Defrost termination to second stage heating cycle .......................................................................10

HP - A 1

Sequence Of Operation

16 SEER Sequence of Operation

16 SEER

Operation of the communicating outdoor unit is managed and
monitored by a microprocessor control in the outdoor unit. Heat
and Cool demand messages are transmitted over a data line
from the comfort control to the indoor and outdoor sections of
the system. System mode and stage requests are received by
the outdoor communicating control board and responded to by
providing control outputs to contactor(s), switch-over solenoid
coil, fan motor and various relay components. Operating
conditions like active Defrost, Fault conditions and Charge
Assist™ operation are transmitted from the outdoor control
over the data line to the rest of the communicating system.
Additional information that is communicated to the rest of the
system includes outdoor temperature, type of equipment installed
(two-stage/two-step, heat pump or air conditioner) and tonnage
which are used during the Auto Discover function to set indoor
airflow and configure the comfort control for the equipment
installed. The control has 12 Light Emitting Diodes (LEDs) used
as status and troubleshooting indicators.

Air Conditioner and Heat Pump models

There are three LEDs used specifically to indicate the current
state of equipment readiness and active stage of operation.

1) STATUS LED: During power-up, this LED will flash fast (2
times per second) for approximately 70 seconds. After the
power-up sequence is complete, the STATUS LED will flash a
slow steady pace (1 time per second). Note: During Charge
Assist™ operation, the STATUS LED will be OFF.

2) Y1 LED: When a request for first stage capacity is sent from
the communicating comfort control, the outdoor control will
respond by turning ON the Y1 LED solid. 24 volts AC will be sent
from the J3/1(Y1) plug energizing MS contactor coil to turn
ON CPR. At the same time, for the 3 and 5 ton models, a Pulse

5

3 4

Width Modulation (PWM) signal is sent from J3/4 (PWM) plug

6

to the outdoor fan motor to run at high speed. With the 2 and
4 ton models, the outdoor fan receives power when the ODF-1

8

relay is energized with 24 volts AC from the control board
terminal T1. A demand message from the comfort control is
sent to the indoor unit for matching, first stage airflow from

9 1

10

the blower motor.

Note: First stage airflow of 80% CFM is Auto Discovered at
power up however; final CFM is configurable through the
Comfort Control Installer Setup ISU # 0182.

1

2

3) Y2 LED: When a request for second stage capacity is sent
from the communicating comfort control, the outdoor control

2

will respond by sending a 20 volt DC signal from the J5 plug
on the control board to the compressor solenoid. The

11

2

1

12

Y2 LED will now turn ON and both the Y1 and Y2 LEDs will
remain on while high stage operation is requested. The high
stage demand message for second stage capacity is received
by the indoor unit and the blower motor will go to high speed

10

without delay.

Note: Two-Step compressors always start unloaded. A 5­second DC solenoid delay will be enforced in the event
that a capacity request begins with 2nd stage demand from
the Comfort Control.

1

When a high stage demand is satisfied, the communicating
comfort control removes the second stage capacity request
and the outdoor control responds by removing the 20 volt DC
signal from plug J5 de-energizing the compressor solenoid.

12

Y2 LED will turn OFF and Y1 LED will remain ON. A demand
message from the comfort control is sent to the indoor unit

10

blower motor to return to first stage airflow.

1

2

11

1

When a request for first stage capacity is satisfied, the
communicating comfort control removes the demand message
from the outdoor and indoor controls. The outdoor control

2 3

responds by removing 24 volt AC from the J3/1 (Y1) plug

2

de-energizing the MS and the CPR. At the same time, for

1

10

4 5

3 and 5 ton models, the PWM signal is removed from plug J3/4

6

(PWM) to the outdoor fan motor and the Y1 LED indicator will
turn OFF. With the 2 and 4 ton models, the 24 volt AC signal is
removed from T1 on the control board de-energizing ODF-

8 7

1 removing power from the outdoor fan motor. The indoor

9

2

blower will also turn off at this time unless continuous fan ON is
selected or after any programmed blower-off delay expires.

4) FAULT LED: Utilized specifically to notify the technician of a
situation related to the performance of the outdoor unit. In total,
there are fourteen faults that the outdoor unit is capable of

2

detecting and reporting to the user. In a communicating
environment, there are seven critical alerts (out of the fourteen
faults total) that could be transmitted to the comfort control to

1

notify the homeowner of a potential problem.

5) COM LED: Used to confirm successful communications and
to identify the number of devices on the data line or
communication buss e.g. three slow flashes indicates three
communicating devices. A fast flashing COM LED indicates loss
of communication.

HP - A 2

16 SEER Sequence of Operation

7

Sequences Of Operation

5

4

15

12

11

8

2

17




16

13

3

14

6

9

10

1

HP - A 3

Sequence Of Operation

16 SEER Sequence of Operation

Refer to the schematic diagram on page 3

Charge Assist™

See the Service Facts in the outdoor unit for detailed information
on the Charge Assist™ feature.

MODE button: To enter the Charge Assist™ feature, press the
MODE button for 2 seconds.

6) CHARGING LED: When using the Charge Assist™ feature to
commission a system or check the charge level, this LED will
flash to indicate the start of the stabilization mode. The LED
flash rate will get faster the closer the system is to determining
the charge level.

7) ADD LED: When using the Charge Assist™ feature to
commission a system or check the charge level, this LED will
turn ON if the operation calculates that the system subcooling
level is low. Should the ADD LED turn ON, 24 volts AC will be
provided from terminals T3 and T4 of the Charge Assist™ control
board to power a charging solenoid, if used. Note: See the
instructions supplied with the BAYCAKT001A (Literature number
18-HH15D1-1). When the charging solenoid receives power,
the valve will open allowing refrigerant to flow from a supply
bottle to the outdoor unit via the Charging Port located near the
service valves. Once enough refrigerant has been added to
meet the subcooling requirement for the system and the
calculated charge level has been achieved, the control will stop
sending 24 volts AC from T3 &T4 de-energizing the charging
solenoid ending the flow of refrigerant to the system. At this
time the ADD LED will turn OFF and the CHARGED LED will turn
ON.

8) CHARGED LED: Utilized as an indicator during Charge Assist™
to acknowledge when the system charge is deemed to be “on
target” for the calculated subcooling level. DIP Switch settings
are required for the Charge Assist™ function to modify the
subcooling level based on line length and lift.

9) REC LED: This LED (Recover) will turn ON if the operation
calculates that the system subcooling level is high. Should the
REC LED turn ON, the system will be turned OFF for up to one
hour with the REC LED illuminated. The one hour lockout can be
exited by pressing the MODE button for two seconds or by
cycling power to the outdoor unit.

10) LOW Pressure LED: System pressure must be at least 90
psi (R-410A) to enter Charge Assist™. If system pressure is
sensed to be low, based on input from the Liquid Pressure
Transducer, this LED will turn ON for 30 seconds followed by
10 fast flashes from the CHARGING LED. These actions indicate
that Charge Assist™ was not allowed.

11) ODT Out Of Range LED: Outside temperature must be at
least 55 degrees F to enter Charge Assist™. If the outside
temperature is sensed to be low, based on input from the Ambient
Temperature Sensor, this LED will flash for 30 seconds followed
by 10 fast flashes from the CHARGING LED.

12) DS13 LED: Functions only to transmit LitePort data which
requires an optic coupler and accompanying software to monitor
or record outdoor unit performance.

Power Interrupt Delay

Power Interrupt protection is part of the control logic to prevent
short cycling of the compressor due to brief power interruptions
(0.1 to 1 second in duration). 24 volt AC power is required as an
input to the control at pin 11 of the J1 connector in order for

13

the power interrupt logic to work. If power is missing on pin 11

13

of the J1 connector, the control board will send an Error 18
message to the comfort control and begin to flash the FAULT

1

2

LED 18 times. If this fault is present, all system operations will
be allowed however; the fault indication will persist until the 24
volt input to J1-11 is restored. Power Interrupt protection, if

13

activated, will de- energize 24 volts AC to the contactor and
hold off compressor operation for approximately 70 seconds.
The STATUS LED plus the Y1 and/or Y2 LEDs will flash for the
duration of the Power Interrupt delay. If a power-off cycle lasts
2 seconds or longer, the Minimum Equipment Off Timer (5 minutes)
will be enforced by the Comfort Control.

Heat Pump Cooling Mode of Operation

When a heat pump system receives a demand message for
cooling capacity, in addition to the compressor contactor and
outdoor fan control signals, there is also a 24 volt AC output
from plug J3/3 (O) to energize the switch over valve (SOV)
solenoid coil. The SOV solenoid coil will be energized with

14

15

15

the start of the first call for cooling and remains energized until
the next call for compressor heat so long as the comfort control
stays in the cooling mode of operation. Even if the comfort
control is switched to the heating mode of operation, the SOV

15

will not be de-energized until the first call for compressor
heat is received.

Heat Pump Heating Mode of Operation

When a heat pump system receives a demand message for
heating capacity, the SOV solenoid coil will not be energized
unless a defrost cycle occurs. When transitioning from the
cooling mode of operation, the SOV will be de-energized with
the start of the first call for heating and will remain de-energized
until the next call for compressor cooling so long as the comfort
control stays in the heating mode of operation.

HP - A 4

16 SEER Sequence of Operation

Sequences Of Operation

Defrost Mode

During the heating cycle, the outdoor coil may become frosted
or iced-up which reduces system capacity. The main control

2

board determines when the system requires a defrost cycle
using Demand Defrost logic. Two thermistor inputs are used to
compare outdoor ambient temperature to coil temperature. The
Ambient Sensor is located below the control box where the
outside air temperature can be sensed and the Coil Sensor is

16

17

located in a copper well attached to one of the lower circuits of
the outside coil. The delta between these sensors is used to
calculate when the outdoor coil is frosted and needs to be
cleared.

Defrost initiation

When a heat pump system is operating in any stage heating and
the control initiates a defrost cycle, 3 and 5 ton controls

2

remove the PWM signal to de-energizes the outdoor fan motor
and 2 and 4 ton controls de-energized ODF-1 which removes
power from the outdoor fan motor. The compressor will turn

7

off for 30 seconds and the control energizes the SOV
solenoid coil to the cooling mode position. The control also

15

sends a demand message to the indoor unit to energize

8

2

2

10

auxiliary heat (if equipped). Auxiliary heat blower speed may
be higher than compressor blower speed and will take
precedence during defrost. The Y1 and/or Y2 LEDs will be ON.

Defrost termination

1. Comfort control demand could be satisfied and turn off the
equipment.

2. Comfort control demand could request the system to run 1
stage heating mode.

3. Comfort control demand could request the system to run 2
stage heating mode.

4. Comfort control demand could request the system to run 3
stage heating mode.

a. For heat pump systems with electric auxiliary heat,
this is 2nd stage compressor with 1st stage auxiliary
heat energized.
b. For dual fuel systems, this is 2nd stage compressor
heat when outdoor temperatures are above the
compressor lockout temperature or 2nd stage gas
furnace (3-stage furnace) below the compressor
lockout temperature.

5. Comfort control demand could request the system to run 4
stage heating mode.

a. For heat pump systems with electric auxiliary heat,
this is 2nd stage compressor with 2nd stage auxiliary
heat energized (2nd and 3rd stage aux heat will both be
energized in this case, if equipped)
b. For dual fuel systems, this is 2nd stage
compressor heat when outdoor temperatures are
above the compressor lockout temperature or 3

rd

stage gas furnace (3-stage furnace) below the
compressor lockout temperature.

st

nd

rd

th

When the control senses that the coil temperature has risen

2

to the programmed termination temperature or that the maximum
15 minute override has expired, the control will re-energize
the outdoor fan motor by sending a PWM signal (3 and 5 ton

7

models) or a 24 volt AC signal from T1 to ODF-1 (2 and 4

2

9 8

ton models). The compressor will turn off for 30 seconds and
the SOV will de-energize back to the heating mode position.

15

At the same time, auxiliary heat will be de-energized and indoor
airflow will return to compressor airflow, matching the stage
request sent from the Comfort Control. The Y1 and/or Y2

1

LEDs will be ON depending on what stage is required to meet
the demand of the Comfort Control.

1

The system will stay in the defrost cycle if the comfort control

1

demand changes from second to first stage capacity request
however; the system will shut down if the comfort control
demand message for first stage capacity ends. The system will
continue the current defrost cycle the next time the comfort
control sends a demand message for compressor heat.

Depending on the load in the structure, at the end of a defrost
cycle, the system could do one of the following:

HP - A 5

Sequence Of Operation

20 SEER Sequence of Operation

20 SEER

Operation of the communicating outdoor unit is managed and
monitored by a microprocessor control in the outdoor unit. Heat
and Cool demand messages are transmitted over a data line
from the comfort control to the indoor and outdoor sections of
the system. System mode and stage requests are received by
the outdoor communicating control board and responded to by
providing control outputs to contactor(s), switch-over solenoid
coil, fan motor and various relay components. Operating
conditions like active Defrost, Fault conditions and Charge
Assist™ operation are transmitted from the outdoor control over
the data line to the rest of the communicating system. Additional
information that is communicated to the rest of the system
includes outdoor temperature, type of equipment installed (two­stage/two-step, heat pump or air conditioner) and tonnage which
are used during the Auto Discover function to set indoor airflow
and configure the comfort control for the equipment installed.
The control has 12 Light Emitting Diodes (LEDs) used as status
and troubleshooting indicators.

Air Conditioner and Heat Pump models

There are three LEDs used specifically to indicate the current
state of equipment readiness and active stage of operation.

1) STATUS LED: During power-up, this LED will flash fast (2
times per second) for approximately 70 seconds. After the
power-up sequence is complete, the STATUS LED will flash a
slow steady pace (1 time per second).

Note: During Charge Assist™ operation, the STATUS LED
will be OFF.

2) Y1 LED: When a request for first stage capacity is sent from
the communicating comfort control, the outdoor control will
respond by turning ON the Y1 LED solid. 24 volts AC will be sent
from the J3/1(Y1) plug energizing MS-LO contactor coil to
turn ON CPR-LO. At the same time, a Pulse Width Modulation

3

5

(PWM) signal is sent from J3/4 (PWM) plug to the outdoor fan

7

motor to run at low speed. A demand message from the
comfort control is sent to the indoor unit for matching, first

1

stage airflow from the blower motor.

Note: First stage airflow is Auto Discovered at power up
however; final CFM is configurable through the Comfort
Control Installer Setup ISU # 0182. Default CFM is as
follows:

1 2

4

6

8

3) Y2 LED: When a request for second stage capacity is sent
from the communicating comfort control, the outdoor control

2

will respond by turning OFF the first stage compressor. 24
volts AC output will be removed from the J3/1 (Y1) plug de­energizing MS-LO contactor coil to turn OFF CPR-LO. Both

4

1

3

5

the Y1 and Y2 LEDs begin flashing (1 time per second) as the
Inter-Stage Delay of one minute is enforced. The demand
message for second stage capacity is received by the indoor

8

unit and the blower motor will go to high speed without delay.
When the one minute Inter-Stage Delay is complete, the outdoor
control will send 24 volts AC from the J3/2 (Y2) plug
energizing MS-HI contactor coil to turn ON CPR-HI. At the

2

10

9

11

same time, a high speed PWM signal is sent to the outdoor fan

7

motor from plug J3/4 (PWM) and both Y1 and Y2 LED

6

indicators will be ON solid.
When a high stage demand is satisfied, the communicating

comfort control removes the second stage capacity request
and the outdoor control responds by removing 24 volts AC
from plug J3/2 (Y2) de-energizing MS-HI contactor coil to
turn OFF CPR-HI. Y2 LED will turn OFF and the Y1 LED begins

1

2

9 10

11

flashing (1 time per second) as the Inter Stage Delay of one
minute is enforced. Without delay, a demand message from the
comfort control is sent to the indoor unit for matching first

1

8

stage airflow from the blower motor. Once the outdoor Inter­Stage Delay is complete, the outdoor control will send 24
volts AC from the J3/1 (Y1) plug energizing MS-LO contactor

4 5

coil to turn ON CPR-LO. At the same time, a low speed

3

PWM signal is sent to the outdoor fan motor from plug J3/4

6

(PWM) and the Y1 LED indicator will be ON solid.

2

7

When a request for first stage capacity is satisfied, the
communicating comfort control removes the demand message
from the outdoor and indoor controls. The outdoor control

2

responds by removing 24 volt AC from the J3/1 (Y1) plug
de-energizing MS-LO to turn OFF CPR-LO. At the same

1

82

4

3

5

time the low speed PWM signal is removed from plug J3/4 (PWM)

6

to the outdoor fan motor and the Y1 LED indicator will turn
OFF. The indoor blower will also turn off at this time unless

7

8

continuous fan ON is selected or after any programmed blower­off delay expires.

4) FAULT LED: Utilized specifically to notify the technician of a
situation related to the performance of the outdoor unit. In total,
there are fourteen faults that the outdoor unit is capable of

2

detecting and reporting locally to the user. In a communicating
environment, there are seven critical alerts (out of the fourteen
faults total) that could be transmitted to the comfort control to

1

notify the homeowner of a potential problem.

2-ton = 50% CFM 1st stage airflow
3-ton = 55% CFM 1st stage airflow
4-ton = 50% CFM 1st stage airflow
5-ton = 65% CFM 1st stage airflow

HP - A 6

5) COM LED: Used to confirm successful communications and
to identify the number of devices on the data line or
communication bus e.g. three slow flashes indicates three
communicating devices. A fast flashing COM LED indicates loss
of communication.

20 SEER Sequence of Operation

Sequences Of Operation

11

5

2

12

3

10

4

9

13

6

16

14

1718

24

26

25




8

23

21

22

15

20

27

7

1

19

HP - A 7

Sequence Of Operation

20 SEER Sequence of Operation

Refer to the schematic diagram on page 7

Charge Assist™

See the Service Facts in the outdoor unit for detailed information
on the Charge Assist™ feature.

MODE button: To enter the Charge Assist™ feature, press the
MODE button for 2 seconds.

6) CHARGING LED: When using the Charge Assist™ feature to
commission a system or check the charge level, this LED will
flash to indicate the start of the stabilization mode. The LED
flash rate will get faster the closer the system is to determining
the charge level.

7) ADD LED: When using the Charge Assist™ feature to
commission a new system or check the charge, the ADD LED
will turn ON if the operation calculates that the system
subcooling level is low. Should this LED turn ON, 24 volts AC
will be provided from terminals T3 and T4 of the Charge Assist™
control board to power a charging solenoid, if used. Note: See
the instructions supplied with the BAYCAKT001A (Literature
number 18-HH15D1-1). When the charging solenoid receives
power, the valve will open allowing refrigerant to flow from a
supply bottle to the outdoor unit via the Charging Port located
near the service valves. Once enough refrigerant has been
added to meet the subcooling requirement for the system and
the calculated charge level has been achieved, the control will
stop sending 24 volts AC from T3 &T4 de-energizing the charging
solenoid ending the flow of refrigerant to the system. At this
time the ADD LED will turn OFF and the CHARGED LED will turn
ON.

8) CHARGED LED: Utilized as an indicator during Charge Assist™
to acknowledge when the system charge is deemed to be “on
target” for the calculated subcooling level. DIP Switch settings
are required to be set before using the Charge Assist™ feature
in order to modify the subcooling level based on line length and
lift.

9) REC LED: This LED (Recover) will turn ON if the operation
calculates that the system subcooling level is high. Should the
REC LED turn ON, the system will be turned OFF for up to one
hour with the REC LED illuminated. The one hour lockout can be
exited by pressing the MODE button for two seconds or by
cycling power to the outdoor unit.

11) ODT Out Of Range LED: Outside temperature must be at
least 55 degrees F to enter Charge Assist™. If the outside
temperature is sensed to be low, based on input from the Ambient
Temperature Sensor, this LED will flash for 30 seconds followed
by 10 fast flashes from the CHARGING LED.

12) DS13 LED: Functions only to transmit LitePort data which
requires an optic coupler and accompanying software to monitor
or record outdoor unit performance.

Note: Charge AssistTM always forces high stage operation.

Power Interrupt Delay

Power Interrupt protection is part of the control logic to prevent
short cycling of the compressor due to brief power interruptions
(0.1 to 1 second in duration). 24 volt AC power is required as an
input to the control at pin 11 of the J1 connector in order for
the Power Interrupt logic to work. If 24 volt AC power is missing
on pin 11 of the J1 connector, the control board will send an
Error 18 message to the comfort control and begin to flash
the FAULT LED 18 times. If this fault is present, all system
operations will be allowed however; the fault indication will
persist until the 24 volt input to J1-11 is restored. Power
Interrupt protection, if activated, will de- energize 24 volts AC to
the contactor and hold off compressor operation for
approximately 70 seconds. The STATUS LED plus the Y1 and/or
Y2 LEDs will flash for the duration of the Power Interrupt delay.
If a power-off cycle lasts 2 seconds or longer, the Minimum
Equipment Off Timer (5 minutes) will be enforced by the Comfort
Control.

Heat Pump Cooling Mode of Operation

When a heat pump system receives a demand message for
cooling capacity, in addition to the compressor contactor and
outdoor fan control signals, there is also a 24 volt AC output
from plug J3/3 (O) to energize the switchover valve (SOV)
solenoid coil. The SOV solenoid coil will be energized
with the start of the first call for cooling and remains energized
until the next call for compressor heat so long as the comfort

1

control stays in the cooling mode of operation.

13

14

12

1

12

14

10) LOW Pressure LED: System pressure must be at least 90
psi (R-410A) to enter Charge Assist™. If system pressure is
sensed to be low, based on input from the Liquid Pressure
Transducer, this LED will turn ON for 30 seconds followed by
10 fast flashes from the CHARGING LED. These actions indicate
that Charge Assist™ was not allowed.

HP - A 8

20 SEER Sequence of Operation

Sequences Of Operation

Heat Pump Heating Mode of Operation

Electronic Expansion Valve (EEV)
The EEV control board receives up to 5 analog signals from
the low voltage side of the main control board. 24 volt AC
power is sent from the J2 plug on the main control board to

17 15

J6/R of the EEV control board while the 24 volt common
connection to J6/B is made at a terminal strip located near the

15

2

16

18

bottom of the control box. When a heat pump system is first
powered up, an audible sound (soft ratcheting sound) may be
heard as the valve drives to the closed position.

Note: The EEV closes with every OFF cycle in the

19

19

heating mode of operation. During Defrost or cooling mode
of operation, the valve will drive to half open.

19

When a heat pump system receives a demand message for
first stage heating capacity, in addition to the compressor
contactor and outdoor fan control signals, there is also a 24 volt
AC output from the main control board plug J3/1 (Y1) to J6/

20

Y1 of the EEV control board. There is a green STATUS
LED on the EEV control board that will flash rapidly to

15

15

indicate that a signal is being sent from plug J1 to the stepper
motor coil which will drive the EEV valve stem to a

19

3

21

predetermined position for first stage refrigerant flow control.
Superheat of 12 degrees (+/-2) is maintained by monitoring
suction line temperature and pressure. Necessary adjustments
to the rate of refrigerant flow are made via the position of the
EEV valve stem which is directly controlled by 12VDC pulse
signals from the J1 plug of the control board.

21

Suction line temperature is determined by thermistor input to
plug J10 of the EEV control board. Suction pressure is

22

determined by transducer input to plug J7 of the EEV control

15

board.

15

23

When a heat pump system receives a demand message for
second stage heating capacity, in addition to the compressor
contactor, outdoor fan control and EEV J6/Y1signals, there
is also a 24 volt AC output from the main control board plug

9 24

J3/Y2 to J6/Y2 of the EEV control board. The green
STATUS LED on the EEV control board will flash rapidly to

15

indicate that a signal is being sent from plug J1 to the stepper
motor coil which will drive the EEV valve stem to a

19

20

2

15

21

predetermined position for second stage refrigerant flow control.
Superheat of 12 degrees (+/-2) is maintained by monitoring
suction line temperature and pressure. Necessary adjustments
to the rate of refrigerant flow are made via the position of the
EEV valve stem which is directly controlled by pulse signals
from the J1 plug of the control board to the stepper motor

19

coil.

21

15

Defrost Mode

During the heating cycle, the outdoor coil may become frosted
or iced-up which reduces system capacity. The main control

2

board determines when the system requires a defrost cycle
using Demand Defrost logic. Two thermistor inputs are used to
compare outdoor ambient temperature to coil temperature. The
Ambient Sensor is located below the control box where the
outside air temperature can be sensed and the Coil Sensor is

25

26

located in a copper well attached to one of the lower circuits of
the outside coil. The delta between these sensors is used to
calculate when the outdoor coil is frosted and needs to be
cleared.

Defrost initiation from first stage heating cycle

When the system is operating in first stage heating and the
control initiates a defrost cycle, the control simultaneously
de-energizes MS-LO to turn OFF CPR-LO, energizes MS­HI to turn ON CPR-HI and de-energizes the PWM signal
to the outdoor fan motor. At the same time the control
energized the SOV solenoid coil to the cooling mode position.
The control also sends a demand message to the indoor unit
to run the blower at 2nd stage cooling speed and energize

2

10

6 7

2

8

4

11

5

14

auxiliary heat (if equipped). Auxiliary heat blower speed may
be higher than 2nd stage compressor blower speed and will
take precedence during defrost. The Y1 and Y2 LEDs will be
ON. The EEV will drive to ½ open based on the presence of
a 24 volt AC signal to J6/O.

19

27

Defrost termination to first stage heating cycle

When the control senses that the coil temperature has risen to
the programmed termination temperature or that the maximum
15 minute override has expired, the control will send a low
speed PWM signal to re-energize the outdoor fan motor.

6

2

7

There is a 12 second time delay (soft switchover) before de­energizing the SOV solenoid coil back to the heating mode
position. The control will then de-energize MS-HI to turn OFF
CPR-HI and after a one minute Inter-Stage Delay, energize
MS-LO to turn ON CPR-LO. At the same time, a demand

11

4

message will be sent to the indoor unit to return to first stage

14

10

5

8

heating airflow and de-energize auxiliary heat. The Y1 LED will
be ON and the EEV control will send the necessary pulse
signals to the stepper motor coil returning the valve to first

15

19

stage heating position and begin monitoring superheat.

HP - A 9

Sequence Of Operation

20 SEER Sequence of Operation

Refer to the schematic diagram on page 7

Defrost initiation from second stage heating cycle

When the system is operating in second stage heating and the
control initiates a defrost cycle, the control simultaneously
de-energizes the PWM signal to the outdoor fan motor
while energizing the SOV solenoid coil to the cooling mode
position. The control also sends a demand message to the
indoor unit to run the blower at 2nd stage cooling speed and

2

2

8

6

14

7

energize auxiliary heat (if equipped). Auxiliary heat blower speed
may be higher than 2nd stage compressor blower speed and will
take precedence during defrost. The Y1 and Y2 LEDs will be
ON. The EEV will drive to ½ open based on the presence of
a 24 volt AC signal to J6/O.

19

27

Defrost termination to second stage heating cycle

When the control senses that the coil temperature has risen

2

to the programmed termination temperature or that the maximum
15 minute override has expired, the control will send a high
speed PWM signal to re-energize the outdoor fan motor.

6

7

There is a 12 second time delay (soft switchover) before de­energizing the SOV solenoid coil back to the heating mode

14

position. At the same time, a demand message will be sent to
the indoor unit to de-energize auxiliary heat. The Y1and Y2
LED will remain ON and the EEV control will send the
necessary pulse signals to the stepper motor coil returning

8

15

19

the valve to second stage heating position and begin monitoring
superheat. The system will stay in the defrost cycle if the comfort
control demand changes from second to first stage capacity
request however; the system will shut down if the comfort
control demand message for first stage capacity ends. The
system will continue the current defrost cycle the next time the
comfort control sends a demand message for compressor

1

heat.
Depending on the load in the structure, at the end of a defrost

cycle, the system could do one of the following:

1. Comfort control demand could be satisfied and turn off the
equipment.

2. Comfort control demand could request the system to run 1
stage heating mode (1 minute stage delay enforced).

3. Comfort control demand could request the system to run 2
stage heating mode.

4. Comfort control demand could request the system to run 3
stage heating mode.

a. For heat pump systems with electric auxiliary heat,
this is 2nd stage compressor with 1st stage auxiliary
heat energized.
b. For dual fuel systems, this is 2nd stage compressor
heat when outdoor temperatures are above the
compressor lockout temperature or 2nd stage gas
furnace (3-stage furnace) below the compressor
lockout temperature.

HP - A 10

5. Comfort control demand could request the system to run 4
stage heating mode.

a. For heat pump systems with electric auxiliary heat,
this is 2nd stage compressor with 2nd stage auxiliary
heat energized (2nd and 3rd stage aux heat will both be
energized in this case, if equipped)
b. For dual fuel systems, this is 2nd stage compressor
heat when outdoor temperatures are above the
compressor lockout temperature or 3rd stage gas
furnace (3-stage furnace) below the compressor
lockout temperature.

st

nd

rd

th

Control Boards

Communicating Air Conditioning and Heat Pump Systems

Section B

20 SEER Heat Pump Model Control Boards...................................................................................... 2

Overview ......................................................................................................................................... 2

Sump Heater Control ...................................................................................................................... 2

Sump heater operation at power up ........................................................................................2

High Pressure Monitor Logic ............................................................................................................. 3

Low Pressure Monitor Logic .............................................................................................................. 3

Cool Mode LPCO Logic...................................................................................................................... 4

Low Temp Lockout in Cool Mode ..................................................................................................... 4

Timing Logic for LPCO Open Events ................................................................................................ 4

Sensor and Control Voltage Fault Detection ..................................................................................... 5

Power Interruption Protection ............................................................................................................ 6

Oil Return Mode 20 Seer Heat Pump Models .................................................................................... 6

Ambient T emperature Sensor and Oil Return Mode ........................................................................ 6

Charge Assist Feature All Models ...................................................................................................... 7

Demand Defrost Cycle Heat Pump Models ........................................................................................ 7

Defrost Component Electrical Wiring .............................................................................................. 7

First Defrost Event.......................................................................................................................... 8

T erminate T emps ............................................................................................................................ 8

Diagnostic LED .............................................................................................................................. 8

Demand Defrost Control Checkout.................................................................................................. 9

Board Variations ................................................................................................................................. 9

HP - B 1

Control Boards

20 SEER Heat Pump Model Control Boards

Overview

Communicating product air conditioners and heat
pump models feature an integrated control board with
communication capability, diagnostic capability,
defrost on demand logic, and advanced system control
functions. The integrated control board has had logic
enhancements and function upgrades since first
introduced.

Figure 1

Sump Heater Control

Sump heat protects the compressor from liquid
migration. Liquid migration occurs when refrigerant
migrates during off cycle periods into the compressor
shell. Keeping the compressor shell warm during off
cycle periods, can prevent liquid migration. During
compressor run operation, the heater must be de­energized to prevent the compressor motor winding
over temperature switch from opening due to an
overheated compressor.

De-energizing the sump heater also decreases system
power usage, increasing overall efficiency .

Sump heater operation at power up and
during a call for compressor operation

This control features advanced sump heat control. For
this function to operate properly, the system must
have a properly working Outdoor Ambient Air Sensor .

At power up, the board enters a warm up routine where
for up to 10 hours, the sump heater is energized. This
cycle will terminate if the compressor operates for at
least 4 minutes during the first 10 hours of power up.

Control features include:

• Sump heater control

• High pressure monitor logic

• Low pressure monitor logic

• Sensor and control voltage fault detection

• Anti-short cycle protection for compressors (Power

Interrupt Protection)

• Oil return mode

• Charge Assist

TM

capability

• Demand defrost cycle

• Time temperature mode when defrost malfunction

occurs

• Defrost mode fault detection

HP - B 2

After a warm up routine, the sump heater will always
be OFF if the outdoor air temperature is above 85F.
When the outdoor air temperature drops below 75F,
the sump heater will be energized until a compressor
runs.

The sump heater will remain off for 30 minutes after a
compressor has stopped running. The sump heaters
are wired in parallel (Figure 2.) to each other so if one
compressor runs, the sump heater cycle will affect
both compressors.

The system is designed so that a compressor and
sump heater will not run at the same time.

Control Boards

Figure 2

High Pressure Monitor Logic

All models are high pressure protected with a high
pressure cut off control during any stage of operation.
(HPCO) The HPCO switch (Figure 3.) opens at 650
PSIG and closes at 500 PSIG. The system has two
HPCO switches to monitor both compressor stages.

Figure 3

The switches are wired between the compressor
contactor low voltage solenoid and terminals 1 and 2
of plug J3 on the Integrated Control Board (Figure 4.)

The integrated control board will monitor system pres­sure via the Liquid Pressure Transducer and will monitor
the HPCO. If it senses an open HPCO event, will start
a 5 minute wait period where the compressor is shut
off. If the HPCO switch closes, the system will re­start the compressor. This cycle will continue for up
to 4 times during a call for heat or cool compressor
operation. If the HPCO opens for a 5th time during the
call, the system will lock out and power will need to
be cycle for the system to reset.

When the system locks out on the 5th event, ERR 80
is displayed on the Comfort Control and a 17 flash is
displayed on the Integrated Control Board Fault LED
(Figure 5.). If a T AM is enabled, the TAM will dial out
an error message.

If the HPCO control is defective due to a short or open
condition in the sensor, the High Pressure Monitor
Logic is ignored. A faulty sensor error ERR 113 will
be displayed on the Comfort Control and a 12 flash
will display on the Integrated Control Board Fault LED.

Figure 5

Typical causes of high system pressure include over
charging, dirty condensing coil, lack of air volume in
heat mode, non condensing gasses in the system,
OD fan failure in cooling mode, or ID fan failure in heat­ing mode.

Figure 4

Low Pressure Monitor Logic

All models are low pressure protected with a low pres­sure cut off control during any stage of operation.
(LPCO) The heat pump LPCO switch opens at 25
PSIG and closes at 45 PSIG. The A/C LPCO switch
opens at 50 PSIG and closes at 70 PSIG . The LPCO
switch (Figure 6.) is monitored during all stages of
operation. (If LPCO is open at power-up, the unit is
locked out of operation.)

HP - B 3

Control Boards

The switch is wired directly to plug J4 (LPCO) (Figure
7&8) on the Integrated Control Board.

Typical causes of low system pressure include under
charging, refrigerant leaks, lack of air volume, and
refrigerant restrictions in the system.

Figure 6

Figure 7

Figure 8

Cool Mode LPCO Logic

Low Temp Lockout in Cool Mode

If the LPCO opens and the Outdoor air temperature is
below 50F, the unit will remain locked out of cooling
operation until the outdoor air temperature reaches 60F .
The Comfort Control will display ERR 79 and the Inte­grated Control Board Fault LED will flash 7 times. The
T AM will dial out if enabled.

Timing Logic for LPCO Open Events

Graph 1

Graph 2

Low pressure monitor A/C trip points

Low pressure monitor

The integrated control board will monitor system pres­sure and will monitor the LPCO. If it senses an open
LPCO event, it will start a 5 minute wait period where
the compressor is shut off. The Comfort Control will
display Wait and the Integrated Control Board Fault
LED will flash 7 times.

If the LPCO switch closes, the system will re-start the
compressor. This cycle will occur for up to two times.
If the LPCO opens for a 3th time during the call, the
system will lock out and power will need to be cycled
for the system to reset.

When the system locks out on the 3rd event, ERR 79
is displayed on the Comfort Control and a 7 flash is
displayed on the Integrated Control Board (See Figure

5.) Fault LED. If a TAM is enabled, the TAM will dial

out an error message.

HP - B 4

Control Boards

Graph 3

Graph 4

Graph 6

Low temp cooling A/C trip points

Sensor and Control Voltage Fault Detection

The Integrated Control Board has the capability to de­tect and report a Liquid Pressure Sensor (see Figure

9) fault and a loss of control voltage at the Y1 connec­tion on plug J1 (see figure 10).

A failed Liquid Pressure Sensor will display a ERR
1 13 at the Comfort Control and will initiate a 12 flash at
the Integrated Control Board Fault LED (see Figure 5).

Graph 5

Low temp heating heat pump trip points

If 24 volts is missing at the Y1 connection on plug J1,
the Comfort Control will display an ERR 18 and the
Integrated Control Board Fault LED will flash 18 times.

Figure 9

HP - B 5

Control Boards

Figure 10

Power Interruption Protection

If a short power interruption is detected, (0.1-1 sec­ond) the control board will protect the compressor from
sudden restarts by initiating a power up delay of 70
seconds. If a power interrupt over 2 seconds is de­tected, a 5 minute off time is started. During the time
delays, a Wait icon is displayed on the Comfort Con­trol. The outdoor fan will be off during delay periods.

Oil Return Mode 20 Seer Heat Pump Models

This mode is activated during long low-stage opera­tion to ensure proper oil return to the compressors in
heating mode low ambient conditions. When the sys­tem is in Oil Return Mode the ST A TUS LED (see Fig-
ure 11) will flash at a medium speed (~2 times per
second)

Figure 11

The Oil Return Mode may also be initiated below 45' F
after 8 hours of cumulative low stage compressor op­eration. Any Defrost cycle will reset the Oil Return
Mode timer. Any high stage compressor operation (for
at least 5 uninterrupted minutes) will reset the low stage
run timer at any outdoor air temperature.

If ODT rises above the low temperature limit (28' F) the
low stage run timer will stop but if the outdoor air tem­perature falls below the low temperature limit the low
stage run timer will resume.

There are two separate timers that can run concur­rently, one for low temperature (below 28F) and one for
high temperature (between 28F and 45F thresholds.
This will ensure an Oil Return Mode execution if nec­essary when outdoor air temperature crosses Low and
High temperature thresholds.

Ambient Temperature Sensor and
Oil Return Mode

The Integrated Control Board will use the Ambient T em­perature Sensor (see Figure 12) to monitor outdoor air
temperature. If there is a problem with the Ambient
T emperature Sensor , the following will occur:

Figure 12

The need for an Oil Return Mode will initiate a forced
Defrost Cycle. Defrost cycles terminate on time or tem­perature.

The Oil Return Mode may be initiated below 28F after
3 hours of cumulative low stage compressor opera­tion. Any Defrost Cycle will reset the Oil Return Mode
timer. Any high stage compressor operation (for at least
15 uninterrupted minutes) will reset the low stage run
timer at any outdoor air temperature.

HP - B 6

Control Boards

• Ambient Sensor fault (open) = Oil Return Mode

exits allowing Defrost Control to assume low tem­perature below 6' F (Defrost every 3 hours)

• Ambient Sensor fault (shorted) = Oil Return Mode

exits (Defrost does not function - same as today)

Err 67 on Comfort Control
5 flash from OD control Fault LED

• Ambient T emperature sensor out of range:

Too low = possible unnecessary Oil

Return Mode initiation

Too high = possible failure to initiate Oil

Return Mode when required

• Coil Sensor out of range:

Too low = Defrost cycle times out

(15 minutes max)

Too high = Defrost cycle exits prematurely

Charge Assist Feature All Models

The Integrated Control Board features advanced charg­ing capability called Charge Assist. Refer to the Charge
Assist section of this book for details.

Demand Defrost Cycle Heat Pump Models

The defrost control board is a demand type defrost
control. The Integrated Control Board monitors the
outdoor air temperature and the outdoor coil tempera­ture and initiates a defrost cycle upon demand.

Defrost Component Electrical Wiring

The Coil Sensor (see Figure 13) is a negative coeffi­cient thermister that changes electrical resistance with
changes in outdoor coil temperature. The thermister
is mounted onto the outdoor coil and connects to the
control board on Plug J6.

Figure 13

The Ambient Temperature Sensor (see Figure 12) is
also a negative coefficient thermister that hangs near
the outdoor coil to sense the temperature of the out­door air. The sensor is mounted to the control board
on Plug J7

Service Facts shipped with the outdoor unit contains
a table (see below) of resistance values versus sensor
temperatures.

During a defrost cycle the switchover valve is ener­gized to cooling mode position, the compressor runs,
the outdoor fan motor is off and back up heat is ener­gized. The system will run in defrost mode until either
the termination temperature or time over ride is reached.
When defrost terminates, the control board will initiate
a soft-switchover routine to minimize noise from the
refrigeration circuit.

HP - B 7

Control Boards

The outdoor fan motor connects to the control board
on Plug J3. During defrost, the motor is off. Service
Facts shipped with the outdoor unit contains a table of
PWM voltage requirements that can be checked to
determine if the control board is sending proper volt­age to the fan motor (see tables below).

16 Seer Out Door Fan Motors

20 Seer Out Door Fan Motors

First Defrost Event

After system power up and 30 minutes in accumu­lated heat mode operation, the integrated control board
will initiate a learning routine defrost cycle. The inte­grated control will learn optimum defrost conditions
during this routine. The learning routine defrost cycle
will terminate on coil temperature or maximum over
ride time.

Terminate Temps
If the outdoor air temperature is above 6F, the maxi-

mum time in defrost is 15 minutes. If a defrost cycle
does not terminate within this time, the defrost will
terminate automatically . At temperatures 6F or below ,
the maximum time in defrost is 12 minutes.

Fault LED

Figure 14

Conditions required for a defrost cycle to be permit­ted:

The outdoor air temperature must be equal to or less
than 52F and the coil temperature must be 34.5F or
less to permit a defrost cycle.

T o initiate defrost, the temperature difference between
outdoor coil and ambient sensors must be 1.9 times
greater than the difference in temperature between a
clean outdoor coil and ambient sensor . (As determined
after the learning routine).

HP - B 8

Forcing a Defrost Cycle and
Speeding Up Defrost Timing

The control board features a test pin that can be jumped
to force the system into a defrost cycle when in heat
mode and to speed up defrost cycle timing during test­ing.

Control Boards

OUTDOOR CONTROL

FIGURE 6.

BOARD - PIN
IDENTIFICA TION

PIN IDENTIFICATION (SEE FIGURE 6.)

1. TEST_COMMON (Shorting any of the other pins to this pin causes the
function of the other pin to be executed. Leaving this pin open results in the
normal mode of operation.)

2. TST = Test (Shorting TEST_COMMON to this pin speeds up all defrost
board timings.)

3. FRC_DFT = Forced Defrost (Short TEST_COMMON to this pin for two [2]
seconds to initiate a forced defrost. Remove the short after defrost
initiates.)

Demand Defrost Control Checkout

Service Facts shipped with the outdoor unit contains
a check out procedure table. The check out procedure
table can also be found in the Reference section of
this book.

16 SEER Control Board

20 SEER Control Board

Board Variations

There are some variations between control boards for
different communicating product models. V ariations
are shown here.

HP - B 9

Control Boards

HP - B 10

Electronic Expansion Valve (EEV) Test

Communicating Air Conditioning and Heat Pump Systems

Section C

Overview............................................................................................................................................. 2

Problems ............................................................................................................................................ 3

Troubleshooting the EEV.................................................................................................................. 3

Electronic Expansion V alve (EEV) control board............................................................................. 3

How to test .......................................................................................................................................... 4

Close valve test .............................................................................................................................. 4

Open valve test............................................................................................................................... 4

Exit test mode................................................................................................................................ 4

Troubleshooting Flow Chart .............................................................................................................. 5

HP - C 1

Electronic Expansion Valve (EEV) Test

Overview

Some communicating system heat pumps use a spe­cial expansion valve called an EEV (Figure 1) in the
outdoor unit.

Figure 1

This expansion valve operates at half open during
cool mode and adjusts to a larger or smaller step po­sition to provide refrigerant metering capability in heat­ing mode. The operation of the valve is controlled by a
circuit board located in the outdoor unit. The EEV
board (Figure 2) receives its power from the 24 volt
transformer located in the outdoor unit on plug J6.

The EEV adjusts its internal orifice size in small incre­ments via commands from the EEV board. The EEV
stepper motor coil connects to the circuit board at
connector J1.

Two sensors provide input information to the EEV
control board. The board has a suction pressure
transducer and a suction line temperature sensor.

These sensors provide the board the needed informa­tion to calculate operating suction vapor superheat.
Based upon the values received from these sensors,
the EEV board will adjust the flow of refrigerant into
the outdoor coil during heat mode to provide superior
control of operational superheat.

Problems

The EEV control board has two LED’s that flash to
indicate operational status and faults. The GREEN
LED is the STATUS LED and the RED LED is the
FAUL T LED.

Figure 2

HP - C 2

T o Coil on EEV

J1

Control Input

J6

24 VAC Stage/Mode

Test Pins

- Test

- Open

- Close

Status LED

Green

Fault LED

Red

Electronic Expansion Valve (EEV) Test

Troubleshooting the EEV

The Electronic Expansion V alve (EEV) installed in this
heat pump is designed to control superheat entering
the compressor when the system is running in me­chanical heating mode. During cooling mode, refriger­ant flow bypasses the EEV via a check valve and is
controlled by the expansion device in the indoor unit.
Therefore, any operational problems observed in cool­ing mode are not caused by the EEV .

Note: The EEV closes with every OFF cycle in the
heating mode of operation. During Defrost and in the
cooling mode of operation, the EEV will drive to half
open. An audible sound can be heard when valve is
changing positions.

Electronic Expansion V alve (EEV) control board
Status LED (Green) (Figure 2)

On: Control has power.

Flashing fast: Control is driving valve (5 seconds

max. drive time)
Flashing pattern: See T able 1.

Fault LED (Red) (Figure 2)

Flashing pattern: See T able 2.

Table 2

Note: V erify the suction line temperature sensor and
suction line pressure transducer and reading properly
when troubleshooting the EEV .

T able 1

Control Input and Status LED - J6

HP - C 3

Electronic Expansion Valve (EEV) Test

How to test

Close valve and open valve tests are active in any mode
of operation

Test Pins: Open, close, test (Figure 2)

Close valve test

1. T ouch CLOSE pin to TEST pin (Figure 4).

Figure 4

EEV drives closed (5 seconds max) and stays closed
for 1.5 minutes (90 seconds.)

1.) Status LED will be flashing.

2.) Gauges should indicate suction pressure drop­ping.

• Valve is working.

• LPCO may trip.

Note: The Close V alve T est will exit after 1.5 minutes
(90 seconds) and will not reinitiate (requires a break
and make to initialize.) T o clear faults stored in memory ,
apply a jumper between Close and Test pins for 10
seconds.

Open valve test

1. T ouch OPEN pin to TEST pin (Figure 5).

Figure 5

EEV drives open (5 seconds max.) and stays open
for 30 seconds.

1.) Status LED will be flashing.

2.) T emperature probe should indicate superheat
falling.

• V alve is working.

Note: If jumper is left on pins, the OPEN VALVE
TEST will be cleared after 30 seconds and will not
reinitiate (requires a break and make to reinitialize.)

Exit test mode

The Open Valve Test or Closed Valve Test can be
cancelled by jumping to the opposite mode Test pin.

The system will return to normal super heat control.
Test mode will cancel if:

1.) Unit enters Defrost.

2.) St age-Delay occurs.

3.) Y1 or Y2 input(s) are lost.

HP - C 4

Troubleshooting Flow Chart

Electronic Expansion Valve (EEV) Test

System is pumping down

in heat mode

Low superheat (flooding)

in heating mode

High superheat

(low suction pressure)

in heating mode

EEV is not sensing that the compressor is ON and in the Heat Mode.

1.) Check plug & harness at J6.

2.) Verify 24VAC at Y1 and/or Y2 inputs to EEV control J6 are
present (not “O”) See Table 1.

System is very low on charge.

1.) Check charge per Service Facts.

EEV valve is stuck closed.

1.) See for Open Valve Test.

EEV valve is stuck open.

1.) See Closed Valve Test.

Sensors are out of calibration.

1.) Verify sensors are accurate.

System is low on charge.

1.) Check charge per Service Facts.

Sensors are out of calibration.

1.) Verify sensors are accurate.

EEV hunting

(Suction pressure moves

up & down)

EEV valve is stuck closed.

1.) See Open Valve Test.

Sensors are out of calibration.

1.) Verify sensors are accurate.

Verify temperature sensor is clipped tight

to suction line and insulated.

Verify Outdoor unit:

1.) Is free and clear of ice and debris.

2.) Has adequate clearance.

3.) Distributor tubes are not bent or kinked.

HP - C 5

Electronic Expansion Valve (EEV) Test

HP - C 6

Sensor Tests

Communicating Air Conditioning and Heat Pump Systems

Section D

Testing the suction line temperature sensor .................................................................................. 2

Introduction.................................................................................................................................... 2

T esting voltage across temperature sensor..................................................................................... 2

Ohm meter..................................................................................................................................... 2

Testing the suction line pressure transducer ................................................................................. 3

Introduction.................................................................................................................................... 3

How to test .................................................................................................................................... 3

Testing the liquid line temperature sensor ..................................................................................... 4

Introduction.................................................................................................................................... 4

T esting voltage across temperature sensor..................................................................................... 4

Ohm meter..................................................................................................................................... 4

Testing the liquid line pressure transducer .................................................................................... 5

Introduction.................................................................................................................................... 5

How to test .................................................................................................................................... 5

HP - D 1

Sensor Tests

Testing the suction line temperature sensor

Introduction

The suction line temperature sensor
(Figure 1) is a negative coefficient type
thermister that changes electrical re­sistance with changes in temperature.
When the temperature it senses drops,
the resistance of the sensor will in-

Figure 1

crease. When the temperature it
senses rises, the resistance of the
sensor will decrease.

T esting voltage across temperature sensor

This test is performed at the EEV board. The outdoor
unit board must be on for this test.

Step 1

Measure the temperature of the suction line (Figure 2).

Figure 2

Figure 3

Table 1

Figure 2

Performed at the
EEV board

Step 2

Measure the DC voltage across the pins at plug J10
(Figure 3). Compare the voltage to the values shown
in T able 1. The voltage should approximate these val­ues. If the voltage measured is not approximate to the
values listed in the table, replace the sensor.

HP - D 2

Ohm meter

Step 1

Shut power to the unit off

Step 2

Unplug the liquid line sensor from plug J10 (Figure 4).

Figure 4

Sensor Tests

Step 3

Use an ohmmeter to measure the resistance of the
suction line sensor (Figure 5). Compare to Table 1
values. If the sensor resistance is not equal to or
close to the table values, replace the sensor .

Figure 5

Testing the suction line pressure transducer

Introduction

The suction line pressure transducer
(Figure 6) senses suction line pres­sure. The transducer connects to
the outdoor EEV control board on
plug J7. The voltage at the J7 plug
can be measured by placing one

Figure 6

meter lead on the +VP test point
and the other onto the T5 T est Point
Common on the outdoor unit con­trol board.

Figure 7

Step 2

Measure the DC voltage between the VP point and
the T5 point (Figure 8). Compare the voltage to the
values shown in T able 2. The voltage should be equal
to or close to these values. If the voltage measured is
not equal to the values listed in the table, replace the
sensor.

Figure 8

Table 2

How to test

Outdoor unit must be on for this test.

Step 1

Measure the refrigerant pressure of the suction line.
(Figure 7)

HP - D 3

Sensor Tests

Testing the liquid line temperature sensor

Introduction

The liquid line temperature sensor (Fig­ure 9) is a negative coefficient type
thermister that changes electrical re­sistance with changes in temperature.
When the temperature it senses drops,
the resistance of the sensor will in­crease. When the temperature it

Figure 9

senses rises, the resistance of the
sensor will decrease.

T esting voltage across temperature sensor

This test is performed at the Comfort Assist control
board. The outdoor unit board must be on for this test.

Step 1

Measure the temperature of the liquid line (Figure 10).

Figure 10

Figure 11

Table 3

Ohm meter

Step 2

Measure the DC voltage across the pins at plug J8
(Figure 1 1.) Compare the voltage to the values shown
in T able 3. The voltage should approximate these val­ues. If the voltage measured is not approximate to the
values listed in the table, replace the sensor.

HP - D 4

Step 1

Shut power to the unit off.

Step 2

Unplug the liquid line sensor from plug J8 (Figure 12).

Figure 12

Sensor Tests

Step 3

Use an ohmmeter to measure the resistance of the
liquid line sensor (Figure 13). Compare to Table 3
values. If the sensor resistance is not equal to or
close to the table values, replace the sensor .

Figure 13

Testing the liquid line pressure transducer

Introduction

The liquid line pressure trans­ducer (Figure 14) senses liq­uid line pressure. The sen­sor is used by the charge as­sist module to determine the
state of system charge, as

Figure 14

well as a high pressure moni-

tor. The transducer connects
to the outdoor unit control board on plug J9. The volt­age at the J9 plug can be measured by placing one
meter lead on the +VP test point and the other onto
the T5 test point common on the outdoor unit control
board.

Figure 15

Step 2

Measure the DC voltage between the +VP point and
the T5 point (Figure 16). Compare the voltage to the
values shown in T able 4. The voltage shown should be
equal to or close to these values. If the voltage mea­sured is not equal to the values listed in the table,
replace the sensor.

Figure 16

Table 4

How to test

Outdoor unit board must be on for this test.

Step 1

Measure the refrigerant pressure of the liquid line (Fig­ure 15).

HP - D 5

Sensor Tests

HP - D 6

Sump Heater

Communicating Air Conditioning and Heat Pump Systems

Section E

Overview ............................................................................................................................................. 2

Troubleshooting ................................................................................................................................. 2

Sump heater fails to energize ........................................................................................................ 2

Sump heater fails to turn OFF during compressor operation .......................................................... 3

HP - E 1

Sump Heater

Overview

Sump heat protects the compressor from liquid
migration. Liquid migration occurs when refrigerant
migrates during off cycle periods into the compressor
shell. Keeping the compressor shell warm during off
cycle periods can prevent liquid migration.

Troubleshooting

If the sump heaters fail to energize, the compressor
may fail to start or may have trouble starting after off
cycle periods.

Sump heater fails to energize

Step 1

Make sure the system operating parameters are met
for Sump Heater operation to occur. There should be
no call for cooling or heating compressor operation.
The compressors should be off for at least 30 minutes.
Outdoor air temperature should be below 75F and the
ambient sensor within the proper temperature range.
Line voltage should be present to the outdoor unit.

Figure 1

If voltage is not present, check for 24 volts at the
Integrated Control Board terminal T2 to ground (Figure

2).

Figure 2

Step 2

Check for 24 volts at the SHR 24 volt terminals (Figure

1). These terminals will have a yellow and blue wires
and are identified on the relay as terminals 1 and 3.
There should be 24 volts present if a call for sump
heater operation is required. If 24 volts is present at
terminals 1 and 3 of the Sump Heater Relay , continue
to Step 3.

HP - E 2

If voltage is not present, the Integrated Control Board
is defective. If voltage is present, there is a break in
the wiring between terminal T2 of the Integrated Control
Board and the connection at the Sump Heater Relay .

Step 3

Check for line voltage across the Sump Heater Relay
at terminals 2 and 4 of the relay (Figure 3).

Figure 3

Sump Heater

If the relay is closed, 0 volts should be present. If line
voltage is measured, the relay contacts are open and
the Sump Heater Relay is defective. Replace the Sump
Heater Relay .

If 0 volts is measured, the relay contacts are closed
and line voltage is being switched to the Sump Heaters.
Check the electrical connections to the heaters. If
the wiring between the Sump Heaters and the Sump
Heater Relay check out good, the heaters have failed.

Sump heater fails to turn OFF
during compressor operation

Step 1

Call for either heat or cool mode compressor operation.

Step 2

Check for 24 volts between Sump Heater Relay
terminals 1 and 3 (Figure 4). 0 volts should be
measured as the relay should be de energized. If 0
volts is measured, continue to S tep 3.

Figure 4

Step 3

If 0 volts is measured between the Sump Heater Relay
terminals 1 and 3, measure the voltage potential
between Sump Heater Relay terminals 2 and 4 (Figure

5). Line voltage should be measured. If 0 volts is
measured, the relay contacts are stuck closed.
Replace the Sump Heater Relay .

Figure 5

If 24 volts is present, check for 24 volts at terminal T2
on the Integrated Control Board. If 24 volts is present,
replace the Integrated Control Board.

HP - E 3

Sump Heater

HP - E 4

Outdoor Fan Motor

Communicating Air Conditioning and Heat Pump Systems

Section F

Introduction......................................................................................................................................... 2

Troubleshooting ................................................................................................................................. 2

HP - F 1

Outdoor Fan Motor

Introduction

Communicating outdoor unit models feature ECM type
outdoor fan motors. The motors are powered by 240
volt line voltage and are speed controlled via a PWM

voltage signal from the outdoor unit control board.

Troubleshooting

If the outdoor fan motor fails to run, or fails to run at
the proper speed, the problem will be either a failed
motor, lack of line voltage to the motor, or a failed
outdoor unit control board.

Step 1

Verify a call for cooling is present by checking the Y1
and Y2 LED light on the outdoor unit control board.

Figure 1

Step 2

Check for 240 volt line voltage to the motor between
terminals 6 and 3 of the 6 pin motor connection plug.
Perform this check on the motor side of the plug (Figure

2). If voltage is not present, Verify the plug connection
is properly seated and/or correct the line voltage
problem to the motor. If line volt age is present, continue
to the next step.

Figure 2

Step 3

With line voltage verified, check for the motor speed
command from the control board. Set digital
multimeter to read DC voltage. Check for DC voltage
between TEST COMMON and the PWM pin on plug
J3 of the outdoor unit control board (Figure 3). DC
voltage should be present during a call for Y1 or Y2
Cooling/Heating operation.

Figure 3

Proper DC voltage ranges between TEST COMMON
and the PWM pin on plug J3 are:

Y1 call: 5-7 VDC
Y2 call: 7.5-10 VDC
Defrost soft switch-over: 0.5 VDC

Step 4

If proper DC voltage is present, along with proper line
voltage, yet the motor does not run, replace the motor .

If line voltage is present, but proper voltage is not
present between the PWM pin on J3 and TEST
COMMON, replace the outdoor unit control board.

HP - F 2

Refrigeration Cycle Problems

Communicating Air Conditioning and Heat Pump Systems

Section G

Check Procedures

Filter drier check ............................................................................................................................ 2

Reversing valve check..................................................................................................................... 2

Cooling Mode........................................................................................................................... 2

Heating Mode .......................................................................................................................... 3

HP - G 1

Refrigeration Cycle Problems

Check Procedures

Filter Drier Check

The filter drier functions to remove debris and
contaminants from the refrigerant. The debris or
contaminants can sometimes plug the filter drier and
restrict the flow of refrigerant, causing system
performance to degrade.

T ools You Will Need:

* T emperature Probe

Step 1

To check for a plugged filter drier, perform a
temperature check at the inlet and outlet of the filter
drier (Figure 1).

Figure 1

Note: Troubleshooting liquid line filter driers and check
valves (when not in the checked position) is similar.
Both components should allow a free flow of refrigerant
without restriction. A 3degree F temperature drop
across a check valve indicates a restricted screen
internal in the check valve. The check valve and liquid
line filter drier should be replaced.

Reversing Valve Check

The reversing valve uses a 24 volt coil to magnetically
shift a spool inside the valve to direct the flow of refrig­erant. This coil is energized during cooling mode and
the defrost cycle of the heat pump mode. Failure of
the coil or electrical circuit allows the valve to default
to the heat pump mode (without defrost cycle).

T ools You Will Need:

* Multimeter
* Screwdriver

Step 2

The temperature difference should be no greater than
3°F. A temperature differential greater than 3°F
indicates a restriction. Replace the filter drier.

HP - G 2

COOLING MODE

Step 1

When a call for cooling is received, yet the unit oper­ates as if in the heat pump mode, check for 24 volts at
the reversing valve coil (Figure 2).

Figure 2

Refrigeration Cycle Problems

Step 2

If voltage is present, shut the system down, discon­nect power to the unit, remove one wire from the coil,
and perform an Ohms check on the coil (Figure 3). An
infinite reading will indicate an open coil. If the coil is
open, replace the coil, restore power, and check for
proper operation. If the ohms reading is good, recon­nect the wire, restore power, and call for cooling.

Figure 3

Step 3

Place the metal end of a screwdriver near the end of
the reversing valve coil (Figure 4). Magnetic pull on the
screwdriver will indicate that the coil is working prop­erly. The valve would then be considered as having
failed, replace the valve.

Figure 4

Step 4

If no voltage is present at the coil during a call for
cooling, check for 24 volts at the defrost control board
(Figure 5). If voltage is present at the defrost control
board, check for a defective wiring harness. No volt­age at the defrost control board indicates a defective
defrost control board or thermostat/wiring.

Figure 5

HEA TING MODE

When operating in the heat pump mode, and the out­door unit exhibits severe frosting, it is possible the
defrost cycle is not being performed. To check this
function, a forced defrost cycle will need to be initi­ated.

Step 1

With the unit operating, use a screwdriver and short
between the TEST_COMMON pin and the FRC_DFT
pin on the defrost control board. (Hold the screwdriver
in place for at least 2 seconds.)(Figure 6.)

Figure 6

HP - G 3

Refrigeration Cycle Problems

Step 2

The reversing valve 24 volt coil will become energized
and the valve will shift. If not, check for the presence of
24 volts at the coil (Figure 7).

Figure 7

Step 3

If voltage is present, shut the system down, discon­nect power to the unit, remove one wire from the coil,
and perform an Ohms check on the coil (Figure 8).
An infinite reading will indicate an open coil. If the coil
is open, replace the coil, restore power, and check for
proper operation. If the ohms reading is good, recon­nect the wire, restore power, and call for heat (Heat
pump mode).

Figure 8

Step 4

Let the unit run for several minutes, then force a de­frost cycle again. Place the metal end of a screw­driver near the end of the reversing valve coil (Figure

9). Magnetic pull on the screwdriver will indicate that
the coil is working properly . The valve would then be
considered mechanically defective, replace the valve.

Figure 9

Step 5

If no voltage is present at the coil during a forced de­frost cycle, check for 24 volts at the defrost control
board (Figure 10). If voltage is present at the defrost
control board, check for a defective wiring harness.
No voltage at the defrost control board indicates a de­fective defrost control board. Replace the board.

HP - G 4

Figure 10

Charge Assist™

Communicating Systems Charge Assist

TM

Section A

Sequence of Operation............................................................................................................................. 2

Control LED Indications............................................................................................................................ 2

Installer’s guide for BAYCAKT001AA Charge Assist™ T ool .................................................................. 3

Connecting The Charge Assist™ Tool ............................................................................................ 3

Charge Assist™ Procedure with a Communicating Comfort Control.................................................... 4

Parameters for using Charge AssistTM............................................................................................ 5

Charge AssistTM System Initialization ............................................................................................ 5

Using Charge Assist ...................................................................................................................... 5

CHARGED Routine.................................................................................................................. 6

ADD Routine ........................................................................................................................... 7

RECOVER Routine.................................................................................................................. 7

Charge Assist™ Procedure for a Non-Communicating 24V AC Control System.................................... 8

Charge Assist™ Quick Instructions.......................................................................................................... 9

Before Adjusting System Charge ................................................................................................... 9

Adjusting System Charge WITHOUT Charge AssistTM tool BA YCAKT001AA (Solenoid Kit)..........1 1

Adjusting System Charge WITH Charge AssistTM tool BAYCAKT001AA (Solenoid Kit).................1 2

Charge Assist

Communicating Systems Quick Connections Guide .............................................................................21

TM

Troubleshooting .............................................................................................................13

Troubleshooting the Charge AssistTM Control .................................................................................13

Troubleshooting Charge AssistTM Control LED Flash Codes ..........................................................15

Fault LED flash codes of 2, 3 or 4 flashes...............................................................................15

Fault LED flash code of 5, Err code 67....................................................................................15

Fault LED flash code of 6, Err code 67....................................................................................16

Fault LED flash code of 7, Err code #79..................................................................................17

Fault LED flash code of #10 ....................................................................................................17

Fault LED flash code of #1 1 ....................................................................................................17

Fault LED flash code of 12......................................................................................................18

Fault LED flash code of 13......................................................................................................19

Fault LED flash code of 14......................................................................................................19

Fault LED flash code of 15......................................................................................................20

CA - A 1

Charge Assist™

Note:

The Charge Assist™ Procedure Details are for educational
purposes only. Please refer to the most recent documents
for updated material before engaging in any of these tests
and procedures

Sequence of Operation

The OUTDOOR UNIT’S Charge Assist ™(CA) Control
Board, is a microprocessor based control which can
communicate digitally with a communicating system’s
thermostat or can be connected to a standard 24V AC
thermostat. The CA control has two modes of operation.
In the normal operating mode, the CA control will
respond to the indoor thermostat call for operation.
The other mode of operation is the Charge Assist™
mode.

T o put the outdoor unit into the Charge Assist™ mode,
press the MODE button for 1 second. The control exits
the normal operating mode and enters the Charge
Assist™ mode.

The CA control completes the following operations:

Control LED Indications

Figure 1

Charge Assist™ Control LED Indications

(Figure 1)

• Y -1 LED ON = First S tage Compressor operation

• Y-1 and Y -2 LEDs Flashing = CA™ control system
is in the one minute compressor off time delay period
before going to Second Stage compressor operation

• Turns on the first or second stage compressor

• Controls the two compressors’ minimum on and off
time and the one minute time delay between stages

• Sends speed signals to the outdoor fan

• Reads the outdoor temperature and sends a digital
outdoor temperature message to the communicating
system thermostat

• Reads the Liquid Line Pressure and temperature

• Is also the Demand Defrost Control when applied to
a Heat Pump

• Can diagnose System Operating Faults.

CA - A 2

• Y-1 LED and Y -2 LED ON = Second S tage
Compressor operation

• Y -1 LED Flashing = CA™ control system is in the
one minute compressor off time delay period before
going back to FIRST stage compressor operation

• Status LED Slow Flash = CA™ control in the
normal operating mode

• Status LED Fast Flash = At power up, this LED will
flash fast for 20 seconds.

• Status LED OFF = CA™ control is in the Charge
Assist™ Mode.

• Com LED ON = At power up, this LED will be on for
20 seconds.

Charge Assist™

• Com LED Flashing = The number of Flashes equals
the number of communicating controls talking on the
Data Line. Example: A communicating system
thermostat + a communicating indoor unit + a
communicating outdoor unit = Three Flashes.

• Fault LED Flashing = When the CA™ control
detects a fault it will flash this LED a different number
of times for each fault detected.

• The following LEDs are used during the CA™ mode
cycle only; LOW PRESSURE, ODT, CHARGING
(ST ABILIZING), ADD, REC, and the CHARGED LED.

Installer’s guide for BA YCAKT001AA

Charge Assist™ Tool

WARNING

Do not connect backwards.

Hoses will contain refrigerant that will be under
pressure.

Figure 2

Step 1-B

Attach Charge Assist™ POR T side of tool to Charge
Assist™ port on unit with refrigerant hose (Figure 3.)

Figure 3

Important - This tool was designed to assist in prop­erly charging a Charge Assist™ equipped Air Condi­tioning or Heat Pump system with refrigerant by in­terfacing with a microprocessor that calculates the
system subcooling.

Device is not intended to charge without at least 50
PSIG of refrigerant pressure or temperatures below
55°F. To be used in cooling mode only.

Connecting The Charge Assist™ T ool

Step 1-A

Attach BOTTLE side of tool to liquid side of refriger­ant bottle with field supplied high pressure hose (Fig­ure 2.)

Step 1-C

Open bottle all the way to release refrigerant. Turn
the knob to PURGE to allow flow. Unscrew connec­tion slowly at the tool to purge the non-condensed
gasses (Figure 4.)

Figure 4

CA - A 3

Charge Assist™

Step 1-D

Re-tighten and turn knob back to off.

Step 1-E

Connect the interface cable from the tool to the cir­cuit board at the “charge solenoid” (T3 and T4.) (Fig­ure 5.)

Figure 5

Step 2

Charging must be done using liquid refrigerant.

Step 3

Purge all hoses of non condensable gases. Charge
AssistTM Tool has a Purge Knob.

Step 4

Plug the Interface Cable from the Charge Assist

TM

T ool onto the unit’s Control Board (Terminals T3 &
T4).

Step 5

Follow instructions for Charge AssistTM Procedures

Step 6

The Green LED on the Charge AssistTM Tool will turn
on indicating the solenoid valve is open.

Step 7

When the Charge AssistTM procedure is completed,
close off refrigerant cylinder and carefully disconnect
hoses.

Charge Assist™ Procedure with a

Communicating Comfort Control

W ARNING

CONT AINS REFRIGERANT!

SYSTEM CONT AINS OIL AND REFRIGERANT UNDER HIGH
PRESSURE. RECOVER REFRIGERANT TO RELIEVE PRESSURE
BEFORE OPENING SYSTEM.

Failure to follow proper procedures can result in
personal illness or injury or severe equipment damage.

Live Electrical Components!

During installation, testing, servicing and
troubleshooting of this product, it may be necessary to
work with live electrical components. Failure to follow
all electrical safety precautions when exposed to live
electrical components could result in death or serious
injury.

CA - A 4

NOTE: On the Charge Assist™ control set the LINE
LENGTH DIP SWITCHES before running system or entering CA
Mode. See Subcool Charging Corrections Table (Figure 6) .

Figure 6

Charge Assist™

Parameters for using Charge Assist

TM

Outdoor T emperature (ODT):

Must be between 55°F and 120°F for R-410A systems
(between 65°F and 100°F for R-22 systems) . If ODT
is outside of this range, the ODT, OUT OF RANGE,
Red LED will flash ON and OFF for 30 seconds. This
error condition causes the CHARGING (STABILIZING)
Amber LED to flash 10 times. The CA control will
then exit the CA mode and the Green Status LED
begins to flash slowly.

Liquid Line Temperature:

(Must be within range) If this sensor is shorted or open,
This error condition causes an 1 1 flash on FAULT LED.

Liquid Line Pressure:

Must be above 90 psig for R-410A systems (50 psig
for R-22 systems). If the liquid pressure falls below
the minimum, the LOW PRESSURE Red LED will
turn on for 30 seconds. This error condition causes
the CA control to flash it s CHARGING (ST ABILIZING)
Amber LED 10 times. The CA control will then exit
the CA mode and it then begins flashing its Green

Status LED slowly .

Using Charge Assist

TM

Step 1

Press MODE button (See Figure 8) for 2 seconds to
enter the CA mode. The CA control takes control of
the system and overrides the Communicating Comfort
Control. The Green STA TUS LED is turned OFF . The
CA control will run the first stage compressor for one
minute. Green LED Y1 is on.

Figure 8

The CA control will then run the second stage
compressor. Green LEDs Y1 and Y2 will then be ON
(Figure 9). The CA control now starts its Charge
Assist™ mode. The CA control will now check the
operating Conditions before continuing the CA Mode.

Figure 9

Charge AssistTM System Initialization

The Communicating Comfort Control will auto-config­ure the system size and airflow requirement at power­up. The Charge Assist™ (CA) Mode will set the in­door blower to 100%, override any blower delays and
run compressor 2nd stage. (Green LEDs Y1 and Y2
will be on. The Green Status LED will be turned off.)
(Figure 7)

Figure 7

OFF

ON
ON

OFF

ON
ON

NOTE: To stop the CA mode at anytime, press the MODE
button. The CA control will then begin slowly flashing its
Green STATUS LED indicating that the CA control is now
in its normal operating mode.

CA - A 5

Charge Assist™

Step 2
Enter Stabilization Routine - The CHARGING

(STABILIZING) Amber LED (Figure 10) will begin to
flash.

Figure 10

The CA control will then indicate the time it will take
for the refrigerant system to stabilize by flashing its
CHARGING (STABILIZING) Amber LED. (See
SUMMARY (Figure 1 1) for flash rate details.)

The CA control may run the system for up to twenty
minutes to insure the refrigerant system is at a steady
operating state. Once the system is at a steady
operating state the CA control will enter the Charging

Routine.

CHARGED Routine

If the CA control determines the system is correctly
charged, the CHARGING (STABILIZING) Amber LED
will be turned OFF and the CHARGED Green LED
will be turned ON (Figure 12).

Figure 12

OFF

ON

The CA control will then exit the charge assist cycle
and return the control of the system to the
Communicating Comfort Control. The Status Green

LED will be slowly flashing. The CHARGED Green
LED will st ay ON for 1 hour.

Step 3
Charging Routine - Charge Assist™ will follow one

of the following routines: Charged, Add, or Recover .

Figure 11

CA - A 6

Charge Assist™

ADD Routine

If the CA control determines refrigerant is required,
the ADD Amber LED will turn ON and the Green
CHARGED LED will begin FLASHING (Figure 13)
according to the CHARGED Green LED flash Rate
Schedule. (See Figure 1 1 for flash rate details.)

Figure 13

ON

FLASH

NOTE: For Automated charging, use BAYCAKT001AA.
When utilizing a Charging accessory Solenoid Kit (BAY­CAKT001) (Figure 14) refer to the instructions in the kit (18­HH15D1-*) for proper hook up. When the Amber ADD LED is
ON the CA control board provides a 24 VAC power for the
accessory solenoid. The CA control will turn off the 24 VAC
power when the Amber ADD LED goes off.

Figure 14

Note: For Manual Charging
Once sufficient charge has been added, the Amber ADD
LED will turn OFF and the Green CHARGED LED will be
turned ON. When the Amber ADD LED turns OFF; stop
adding refrigerant. The Green CHARGED LED will stay

on for 5 minutes while the unit runs. The CA control will
now exit the Charge Assist™ cycle and returns control to
the Communicating Comfort Control.

RECOVER Routine
If the CA control determines there is excessive

refrigerant in the system, the REC Red LED will be

turned ON (Figure 15).

Figure 15

ON

The CA control will lock the system off for one hour
and it will then exit the CA cycle. The REC Red LED
will stay ON for 1 hour . The CA control lock out period
can be stopped by pressing the MODE button for 2
seconds. Status LED will be of f during lockout.

When refrigerant is being added, the CA control will

exit the Charge Assist™ cycle if the liquid line pressure
does not increase by 4 psi in 50 minutes or if the
liquid line pressure does not get within the 20 psi
of the required charged pressure within 1 hour.

NOTE: Personality Module (PM) contains model
specific information needed for system operation - Do

Not Remove.

NOTE: The word ‘Wait’ will be displayed on the
Communicating Comfort Control when the system is in
the CA mode. The Communicating Comfort Control does
not control the system operation when the system is
running in the CA Mode. Any changes in the
Communicating Comfort Control programming made
during the CA mode of operation will become effective
after the CA mode ends.

CA - A 7

Charge Assist™

NOTE: Charge Assist™ IS NOT allowed when a heat
pump is operating in the heating cycle. If the mode button
is pressed during an active compressor heat call, the
CHARGING (STABILIZING) LED will flash 10 times
indicating that CA is not allowed. Once an active call for
compressor heat has ended, CA may be entered.

CAUTION: Minimum equipment off time is bypassed
during Charge Assist™. Avoid cycling compressor
quickly . Observe the recommended 5-minute minimum
off time for compressor protection.

Charge Assist™ Procedure for a Non-

Communicating 24V AC Control System

STEP 1

Outdoor units coupled with 24 volt indoor units (outdoor
units require BA Y ACHP024* for 24V operation) require
the technician to set up the Variable Speed (VS) Air
Handler or VS Furnace with the DIP switches for the
size of the equipment installed. (Unit tonnage, CFM
per ton 350, 400, 450 required, the blower delays and
Heating airflow) CA cycle is compatible with
ENHANCED Mode.

STEP 4

After the CA control exits the CA mode CYCLE, the
technician must then return the NON­COMMUNICA TING 24 volt indoor CONTROL to the
desired customer setting.

Charge Assist™ Quick Instructions

For detailed Charge AssistTM instructions, see the
equipment Service Facts.

Before Adjusting System Charge

Step 1

Verify that the out door temperature is between 55°F
and 120°F and the indoor temperature is between 70°F
and 80°F (Figure 16). Add system heat if needed.

Figure 16

STEP 2

A technician must set the indoor system control to
call for the SECOND STAGE of COOLING . The indoor
CONTROL must be set low enough to ensure the
system continues to run in SECOND STAGE of
COOLING throughout the CA mode cycle. The CA
control will exit the CA mode CYCLE if the system
control does not stay in the SECOND ST AGE cooling
cycle. (The CA Control must see 24 V olt s AC call on
both Y1 and Y2.)

STEP 3

Press the mode button on the CA board and follow
the CA procedures starting with STEP 1 in the

Communicating Comfort Control Section above.

CA - A 8

Step 2

At the indoor unit, set the dip switches (Figure 17) for
the appropriate system size and airflow. Note: If using
a communicating comfort control, these settings will
be auto-configured.

Figure 17

Step 3

Set the indoor system control to call for second stage
cooling throughout the charging process (Figure 18).
Note: If using a communicating comfort control, this
step is not required as the system will perform this
task once Charge AssistTM mode is started.

Figure 18

Step 4

At the outdoor unit, set the Charge AssistTM dip
switches (Figure 19) as determined from the appropri­ate charging correction table found on the next page
(Figure 20).

Figure 19

Charge Assist™

Step 5

If no Charge AssistTM tool BA YCAKT001AA (solenoid
kit) is used, continue to “Adjusting System Charge

WITHOUT Charge AssistTM tool BAYCAKT001AA
(Solenoid Kit)”

If using the Charge AssistTM tool BA YCAKT001AA (so­lenoid kit), continue to “Adjusting System Charge

WITH Charge AssistTM tool BA YCAKT001AA (So­lenoid Kit)”

CA - A 9

Figure 20

Charge Assist™

CA - A 10

Charge Assist™

Adjusting System Charge WITHOUT Charge
AssistTM T ool BA YCAKT001AA (Solenoid Kit)

Step 1

Hook-up gauges to the refrigerant bottle and the Charge
AssistTM port (Figure 21).

Important: Purge refrigerant lines during hook-up.

Figure 21

Note: Charging set-up should be for liquid refrigerant. Picture shows
inverted bottle, not all bottles need to be inverted. Some cylinders
must be inverted for liquid and others contain a dip tube for liquid
refrigerant. This feature requires liquid charging. Determine how to
position the bottle.

Step 2

Start Charge AssistTM by pressing the MODE button
for a minimum of 2 seconds (Figure 22).

Figure 22

Step 3

The system may need to run up to 20 minutes to sta­bilize.

Note: During system stabilization, the STABILIZING LED will flash.
Note: If the system has been running, it may go straight to Step

4.
Note: For communicating systems that have not been running,

the low stage compressor will run for one minute and then turn
off. After one minute (inter-stage delay), the high stage com­pressor will start and the stabilization routine will begin.

Step 4

Once the system has stabilized, review the CHARG­ING LEDs (Figure 23) to determine what, if any , sys­tem charge adjustment is required:

• If the amber ADD LED is on and the CHARGED LED

is flashing, then the system is under charged. Add
refrigerant until the CHARGED LED turns on (not flash­ing) and the ADD LED is of f.

• If the red REC LED is on, then the system is over

charged. The system will stop running and be locked
out for one hour. Press the mode button to exit the
Charge AssistTM lockout. Refrigerant must be recov­ered before re-starting Charge AssistTM.

• If the green CHARGED LED is on, Charge Assist

TM

has determined that the system is correctly charged.

Figure 23

Note: To stop Charge AssistTM at anytime, press the MODE
button.

CA - A 11

Charge Assist™

Adjusting System Charge WITH Charge
AssistTM T ool BA YCAKT001AA (Solenoid Kit)

Step 1

Hook-up the solenoid to the refrigerant bottle and the
Charge AssistTM port (Figure 24).

IMPORT ANT : Purge refrigerant lines during hook-up.
Once purge is complete, be certain to return the purge
knob on solenoid to the OFF position (Figure 25)!

Figure 24

Note: Charging set-up should be for liquid refrigerant. Picture shows
inverted bottle, not all bottles need to be inverted. Some cylinders must
be inverted for liquid and others contain a dip tube for liquid refrigerant.
This feature requires liquid charging. Determine how to position the bottle.

Figure 25

Step 3

Start Charge AssistTM by pressing the MODE button
for a minimum of 2 seconds (Figure 27).

Figure 27

Note: To stop Charge AssistTM at anytime, press the MODE
button.

Step 4

The system may need to run up to 20 minutes to sta­bilize.

Note: During system stabilization, the STABILIZING LED will
flash.

Note: If the system has been running, it may go straight to Step

4.
Note: For communicating systems that have not been running,

the low stage compressor will run for one minute and then turn
off. After one minute (inter-stage delay), the high stage com­pressor will start and the stabilization routine will begin.

Note: Charging set-up should be for liquid refrigerant.

Step 2

Plug in the solenoid to the Charge AssistTM control
board (Figure 26).

Figure 26

CA - A 12

Step 5

Once the system has stabilized, Charge AssistTM will
do one of the following:

• If charge is required, the solenoid will automatically

open to add refrigerant to the system. Once properly
charged the solenoid will automatically close. The
CHARGED LED turns on (not flashing) and the ADD
LED is off.

• If the red REC LED is on - See “Adjusting System

Charge WITHOUT Charge AssistTM Tool
BA YCAKT001AA (Solenoid Kit)” - Step 4

• If the green CHARGED LED is on, Charge Assist

TM

has determined that the system is correctly charged.

Charge Assist™

Charge Assist

TM

Troubleshooting

Troubleshooting the Charge AssistTM Control

Step 1

Is there 24 volts AC at the Charge Assist™ control at
plug J2 pins R and B (Figure 28)?

Figure 28

Yes: Go to S tep 2 for a communicating system. For

a 24 volt AC control system, go to Step 4.

No: Restore the 24 volt AC power to the outdoor

unit.

Note: A communicating system the 24 volt AC is sup­plied by the outdoor unit’s transformer.

Note: A 24 volt AC control system the 24 volt A/C power
is supplied by the indoor unit’s transformer.

Step 2

Is the Charge Assist™ control’ s COM LED (Figure 29)
flashing the correct number of times? Example: A sys-

tem that has a communicating thermostat, a commu­nicating furnace or air handler and a communicating
outdoor unit the COM LED should be flashing in groups
of three flashes.

Figure 29

Yes: The Charge Assist™ control is communicat-

ing with the control system. Go to Step 3.

No: The COM LED is flashing fast, go to the trouble

shooting ERR code 89 or 91 section.

Step 3

Is the Status LED (Figure 30) flashing slowly?

Figure 30

Yes: Go to Step 4.
No: If the Status LED is out, go to Step 5. If the

Status will not stop flashing fast, replace the Charge
Assist™ control.

Step 4

Does Y1 or Y2 LEDs (Figure 31) come on when a call
for compressor operation is placed at the comfort sen­sor thermostat or the 24 volt A/C control thermost at?

Note: When the comfort sensor thermostat is set up
for compressor operation and WAIT is displayed on
the sensor display, there will be a five minute delay
before Y1 or Y2 will come on.

Note: A 24 volt A/C digital thermostat may have a time
delay when the cooling set point is changed to prevent
compressor short cycling.

Figure 31

CA - A 13

Charge Assist™

Yes: Go to Step 6.
No: On an AC unit, replace the Charge Assist™

Control. Heat pump units only check for 24 volts
AC across Charge Assist™ Control LPCO plug J4
(Figure 32A). The fault LED (Figure 32B) should be
flashing in groups of seven flashes if the LPCO
switch is open. If 24 volts AC is present, the heat
pump is locked out by the Low Pressure Cut Out
Switch. Repair system as needed. If there is no
24 volts AC at plug J4, replace the Charge Assist™
Control.

Figure 32A

Figure 32B

Step 5

Push in and hold the Mode switch (Figure 33) on the
Charge Assist™ Control for one second. Does the
St atus LED now flash slowly?

Figure 33

Step 6

Is there 24 volts AC at plug J3 between its pins Y1 and
B (Figure 34) or Y2 and B (Figure 35)?

Note: There should be 24 volts present only between
pins Y1 and B when LED Y1 is on or 24 volts AC
between pins Y2 and B when LED Y2 is on.

Figure 34

Figure 35

Yes: Go to Step 4.
No: Replace the Charge Assist™ Control.

CA - A 14

Yes: Charge Assist™ control is working correctly;

fault is with the unit’s wiring, its contactors or its
compressor.

No: Replace the Charge Assist™ control.

Charge Assist™

Troubleshooting Charge AssistTM Control
LED Flash Codes

If the comfort control is displaying Err code 89 or 91 or
if the Charge Assist™ control fault LED is flashing a
one flash code go to troubleshooting procedures for
Err code 89 or 91

Fault LED flash codes of 2, 3 or 4 flashes

Go to defrost control troubleshooting procedures.
These faults are not reported to the Comfort Control
as Err codes.

Fault LED flash code of 5, Err code 67

Will be displayed at the Comfort Control. The fault
LED (Figure 36) will be flashing in groups of five flashes.
This indicates that the outdoor Ambient Temperature
Sensor is reading out of range.

Figure 36

At the Charge Assist™ Control, read the DC voltage
at the Ambient Temperature Sensor plug J7 with the
sensor plugged in or unplug the sensor and read the
resistance of the sensor (Figure 37).

Figure 37

CA - A 15

Charge Assist™

Does the ambient temperature and the DC voltage or
its resistance in ohms read at the Ambient Tempera­ture Sensor plug J7 agree with the temperature, resis­tance and voltage chart? (See Reference Materials)

Yes: Unplug and re-plug the Ambient T emperature

Sensor plug (Figure 38) several times to insure it is
making good contact with the control pins. Turn off
the 24 volts AC to the Charge Assist™ Control and
then re-power the control. If the 5 flash codes con­tinue to be displayed, replace the Charge Assist™
Control.

No: Unplug and re-plug the Ambient Temperature

Sensor plug J7 (Figure 38) several times to insure
that it is making good contact with the Charge As­sist™ Control plug, then re-check the DC voltage at
plug J7 or unplug the sensor and read the resis­tance of the sensor. If the DC volt age or resistance
at plug J7 and the ambient temperature still does
not agree with the temperature, resistance and volt­age chart, replace the Ambient Temperature Sen­sor.

Figure 38

the sensor plugged in or unplug the sensor and read
the resistance of the sensor (Figure 39).

Figure 39

Does the coil temperature and the DC voltage or its
resistance in ohms read at the Coil Temperature Sen­sor plug J6 agree with the temperature, resistance and
voltage chart? (See Reference Materials)

Yes: Unplug and re-plug the Coil Temperature Sen-

sor plug J6 (Figure 40) several times to insure it is
making good contact with the control pins. Turn off
the 24 volts AC to the Charge Assist™ Control and
then re-power the control. If the 6 flash codes con­tinue to be displayed replace the Charge Assist™
Control.

Fault LED flash code of 6, Err code 67

Displayed on heat pump Comfort Controls only . This
sensor is used only on heat pump models. The fault
LED (Figure 36) will be flashing in groups of six flashes.
This indicates that the Coil T emperature Sensor is read­ing out of range. Read the DC voltage at the Charge
Assist™ Control Coil T emperature Sensor plug J6 with

CA - A 16

No: Unplug and re-plug the Coil T emperature Sen-

sor plug (Figure 40) several times to insure that it
is making good contact with the Charge Assist™
Control plug J6, then re-check the DC voltage at
plug J6 or unplug the sensor and read the resis­tance of the sensor . If the DC voltage and tempera­ture or resistance and temperature does not agree
with the temperature, resistance and voltage chart,
replace the Coil T emperature Sensor .

Charge Assist™

Figure 40

Fault LED flash code of 7, Err code #79

This fault code only applies to the Heat Pump models
in the heating or cooling cycle. During the defrost
cycle, the LPCO switch is not checked by the Charge
Assist™ Control. The fault LED (Figure 36) will be
flashing in groups of seven flashes. This is an indica­tion that the Low Pressure Cut-Out switch (LPCO) is
open. Check the suction pressure, it must be above
nine pounds.

Is the system suction pressure above nine pounds?

Yes: Check the voltage at the LPCO plug J4 (Fig-

ure 41A). If 24 volts AC is present at plug J4, un­plug the LPCO and jumper the two pins of J4 to­gether (Figure 41B). Turn of f the 24 volts AC to the
Charge Assist™ Control and then re-power the con­trol. The fault LED should go out and the outdoor
unit should come on when a call for heat or cooling
is placed at the Comfort Control. If the fault LED
continues to flash in groups of seven and the out­door unit will not come on, replace the Charge As­sist™ Control.

Figure 41A

Figure 41B

Fault LED flash code of #10

This fault will only appear when the Charge Assist™
Control is being operated with a standard 24 volt AC
thermostat, non-communicating type, and thermostat
leads Y1 and Y2 are reversed.

Fault LED flash code of #11

The fault LED (Figure 20) will be flashing in groups of
11 flashes. This indicates that the Liquid Line Tem­perature Sensor is reading out of range.

At the Charge Assist™ Control read the DC volt age at
the Liquid Temperature Sensor plug J8 with the sen­sor plugged in or unplug the sensor and read the re­sistance of the sensor (Figure 42).

Figure 42

No: Repair Refrigerant System as needed.

CA - A 17

Charge Assist™

Does the liquid line temperature and the DC voltage or
resistance read at the Liquid T emperature Sensor plug
J8 agree with the temperature, resistance and voltage
chart? (See Reference Materials)

Yes: Unplug and re-plug the Liquid Line T empera-

ture Sensor (Figure 43) several times to insure it is
making good contact with the control pins. Turn off
the 24 volts AC to the Charge Assist™ Control and
then re-power the control. If the 1 1 flash codes con­tinue to be displayed, replace the Charge Assist™
Control.

No: Unplug and re-plug the Liquid Line T emperature

Sensor (Figure 43) several times to insure that it is
making good contact with the Charge Assist™ Con­trol plug; then re-check the DC voltage or resistance.
If the DC voltage and temperature or resistance still
does not agree with the Liquid Line temperature,
resistance and voltage chart, replace the Liquid Line
T emperature Sensor .

Figure 43

Fault LED flash code of 12

The fault LED (Figure 36) will be flashing in groups of
12 flashes. This indicates that the Liquid Pressure
Sensor is reading out of range.

Figure 44

Step 2

Read the liquid line pressure with a calibrated high
pressure gauge.

Does the liquid line pressure and the DC voltage read
at the Liquid Pressure Sensor plug J9 test point + VP
and the 24 volt AC terminal T5 agree with the pressure
shown on the liquid line pressure and voltage chart?
(See Reference Materials)

Yes: Replace the Charge Assist™ Control.
No: If there is 4.9 volts DC between the black com-

mon wire and the red power wire at pressure plug
J9 (Figure 45A) and the pressure and voltage mea­sured do not match the liquid line pressure and volt­age chart replace the pressure transducer. If there
is no voltage between the black common wire and
the red power wire or the 4.9 volts DC is lower than

4.9 volts DC, unplug the transducer (Figure 45B)
and re-check the voltage at plug J9. If the voltage
at the pressure plug J9, with the pressure trans­ducer unplugged, now reads 4.9 volts, replace the
transducer. If the volt age at the pressure plugs re­mains low when the transducer is unplugged, re­place the Charge Assist™ Control.

Step 1

Read the DC voltage at the Liquid Line Pressure Sen­sor plug J9 test point (+ VP) and the 24 volt common
terminal T5 with the sensor plugged in (Figure 44.)

CA - A 18

Charge Assist™

Figure 45A

Figure 45B

Fault LED flash code of 13

The fault LED (Figure 36) will be flashing in groups of
13 flashes. This indicates that the outdoor External
Ambient T emperature Sensor is reading out of range.

Read the DC voltage at the External Ambient Tem­perature Sensor EXT . ODT terminal boards (TB1) with
the sensor connected or remove the sensor leads and
read the resistance of the sensor (Figure 46).

Figure 46

Yes: Turn off the 24 volts A/C to the Charge As-

sist™ Control and then re-power the control. If the
13 flash codes continue to be displayed, replace
the Charge Assist™ Control. Note: Disconnect the

External Ambient T emperature Sensor and re-power
the control system. The Charge Assist™ Control
will now use the internal Ambient Sensor.

No: When the DC voltage and temperature do not

agree with the external temperature, resistance tem­perature, resistance and voltage chart, replace the
External Ambient T emperature Sensor.

Fault LED flash code of 14

Error code of ERR 1 14 will be reported to the Comfort
Control. This indicates that the Personality Module
plugged into the Charge Assist™ Control is unplugged
or its stored information is not usable.

Is the Personality Module (Figure 47) plugged into the
Charge Assist™ Control?

Figure 47

Do the External Ambient T emperature and the DC volt­age read at the External Ambient T emperature Sensor
(TB) or resistance of the sensor agree with the exter­nal temperature, resistance and voltage chart? (See
Reference Materials)

Yes: Turn off the 24 volt A/C supply to the Charge

Assist™ Control and then re-power. Fault code
should clear itself; if the fault code does not clear
itself, replace the Personality Module. Note: To

order a Personality Module you must have the com­plete model and serial number from the unit it goes
into.

No: Turn off the 24 volt AC supply and the plug the

Personality Module back into its socket #J12. Re­power the Charge Assist™ Control, the fault code
should clear itself.

CA - A 19

Charge Assist™

Fault LED flash code of 15

This indicates that there are multiple External Ambi­ent Temperature sensors installed. Only one or four
sensors can be connected to the EXT . terminal board
on the Charge Assist™ Control.

CA - A 20