Day and Night CCH9, HCH9, HCH6, TCH9, TCH6 Installation Instructions Manual

INSTALLATION INSTRUCTIONS

R−410A Two−Stage Split System Heat Pumps

CCH9, HCH9, TCH9
CCH6, HCH6, TCH6

These instructions must be read and understood completely before attempting installation.

Safety Labeling and Signal Words

DANGER, WARNING, CAUTION, and
NOTE

The signal words DANGER, WARNING,
CAUTION, and NOTE are used to identify levels of

hazard seriousness. The signal word DANGER is
only used on product labels to signify an immediate
hazard. The signal words WARNING, CAUTION,
and NOTE will be used on product labels and
throughout this manual and other manuals that may
apply to the product.

DANGER − Immediate hazards which will result in
severe personal injury or death.

WARNING − Hazards or unsafe practices which
could result in severe personal injury or death.

CAUTION − Hazards or unsafe practices which
may result in minor personal injury or product or

property damage.

NOTE − Used to highlight suggestions which will
result in enhanced installation, reliability, or
operation.

Signal Words in Manuals

The signal word WARNING is used throughout this
manual in the following manner:

WARNING

WARNING

!

The signal word CAUTION is used throughout this
manual in the following manner:

!

Signal Words on Product Labeling

Signal words are used in combination with colors
and/or pictures on product labels.

CAUTION

TABLE OF CONTENTS

Safety Considerations 2...........................

Installation Recommendations 2...................

Installation 2.....................................

Start−up Procedure 7.............................

System Functions & Sequence of Operation 9.......

Defrost 10.......................................

Troubleshooting 11...............................

Status Codes 15.................................

R−410A Quick Reference Guide 16.................

!

ELECTRICAL SHOCK HAZARD

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

Before installing, modifying, or servicing system,
main electrical disconnect switch must be in the
OFF position. There may be more than 1 discon­nect switch. Lock out and tag switch with a suit­able warning label.

!

CUT HAZARD

Failure to follow this caution may result in per­sonal injury

Sheet metal parts may have sharp edges or burrs.
Use care and wear appropriate protective clothing
and gloves when handling parts.

Specifications subject to change without notice.

WARNING

CAUTION

428 01 1703 01 6/17/13

INSTALLATION INSTRUCTIONS R−410A Split System Heat Pumps

SAFETY CONSIDERATIONS

Improper installation, adjustment, alteration, service,
maintenance, or use can cause explosion, fire, electrical
shock, or other conditions which may cause death, personal
injury, or property damage. Consult a qualified installer,
service agency, or your distributor or branch for information or
assistance. The qualified installer or agency must use
factory−authorized kits or accessories when modifying this
product. Refer to the individual instructions packaged with
the kits or accessories when installing.

Follow all safety codes. Wear safety glasses, protective
clothing, and work gloves. Use quenching cloth for brazing
operations. Have fire extinguisher available. Read these
instructions thoroughly and follow all warnings or cautions
included in literature and attached to the unit. Consult local
building codes and current editions of the National Electrical
Code ( NEC ) NFPA 70. In Canada, refer to current editions
of the Canadian electrical code CSA 22.1.

Recognize safety information. This is the safety−alert symbol

!

!

When you see this symbol on the unit and in instructions
or manuals, be alert to the potential for personal injury.
Understand these signal words; DANGER, WARNING, and
CAUTION. These words are used with the safety−alert
symbol. DANGER identifies the most serious hazards which
will result in severe personal injury or death. WARNING
signifies hazards which could result in personal injury or
death. CAUTION is used to identify unsafe practices which
would result in minor personal injury or product and property
damage. NOTE is used to highlight suggestions which will
result in enhanced installation, reliability, or operation.

INSTALLATION RECOMMENDATIONS

NOTE: In some cases noise in the living area has been

traced to gas pulsations from improper installation of
equipment.

1. Locate unit away from windows, patios, decks, etc.
where unit operation sound may disturb customer.

2. Ensure that vapor and liquid tube diameters are
appropriate for unit capacity.

3. Run refrigerant tubes as directly as possible by
avoiding unnecessary turns and bends.

4. Leave some slack between structure and unit to
absorb vibration.

5. When passing refrigerant tubes through the wall, seal
opening with RTV or other pliable silicon−based caulk.
(See Fig. 1.)

6. Avoid direct tubing contact with water pipes, duct work,
floor joists, wall studs, floors, and walls.

7. Do not suspend refrigerant tubing from joists and studs
with a rigid wire or strap which comes in direct contact
with tubing.(See Fig. 1.)

8. Ensure that tubing insulation is pliable and completely
surrounds vapor tube.

9. When necessary, use hanger straps which are 1 in.
(25.4 mm) wide and conform to shape of tubing
insulation. (See Fig. 1.)

10. Isolate hanger straps from insulation by using metal
sleeves bent to conform to shape of insulation.

2 428 01 1703 01

Figure 1

When outdoor unit is connected to factory−approved indoor
unit, outdoor unit contains system refrigerant charge for
operation with AHRI rated indoor unit when connected by 15
ft. (4.57 m) of field−supplied or factory accessory tubing. For
proper unit operation, check refrigerant charge using
charging information located on control box cover and/or in
the Check Charge section of this instruction.

IMPORTANT: Maximum liquid−line size is 3/8−in. OD for all
residential applications including long line.

IMPORTANT: Always install the factory−supplied liquid−line
filter drier. Obtain replacement filter driers from your
distributor or branch.

Check Equipment and Job Site

Unpack Unit

Move to final location. Remove carton taking care not to
damage unit.

Inspect Equipment

File claim with shipping company prior to installation if
shipment is damaged or incomplete. Locate unit rating plate
on unit corner panel. It contains information needed to
properly install unit. Check rating plate to be sure unit
matches job specifications.

Install on a Solid, Level Mounting Pad

If conditions or local codes require the unit be attached to
pad, tie down bolts should be used and fastened through
knockouts provided in unit base pan. Refer to unit mounting
pattern in Fig. 2 to determine base pan size and knockout
hole location.

For hurricane tie downs − contact your local distributor for
details and PE (Professional Certification), if required by local
authorities.

On rooftop applications, mount on level platform or frame.
Place unit above a load−bearing wall and isolate unit and
tubing set from structure. Arrange supporting members to
adequately support unit and minimize transmission of
vibration to building. Consult local codes governing rooftop
applications.

Roof mounted units exposed to winds may require wind
baffles. Consult the Low−Ambient pressure switch installation
instructions for wind baffle construction.

NOTE: Unit must be level to within ±2 (±3/8 in./ft..) per

Specifications subject to change without notice.

compressor manufacturer specifications.

Connecting Tube Installation

Avoid contact between tubing and structureNOTE:

OUTDOOR WALL INDOOR WALL

CAULK

INSULATION

THROUGH THE WALL

HANGER STRAP

(AROUND VAPOR

TUBE ONLY)

1″ (25.4 mm)MIN.

SUSPENSION

INSTALLATION

LIQUID TUBE

VAPOR TUBE

JOIST

INSULATION

VAPOR TUBE

LIQUID TUBE

INSTALLATION INSTRUCTIONS R−410A Split System Heat Pumps

Clearance Requirements

When installing, allow sufficient space for airflow clearance,
wiring, refrigerant piping, and service. Allow 24 in. (610 mm)
clearance to service end of unit and 48 in. (1219.2 mm)
above unit. For proper airflow, a 6 in. (152.4 mm) clearance
on one side of unit and 12 in. (304.8 mm) on all remaining
sides must be maintained. Maintain a distance of 24 in.
(609.6 mm) between units. Position so water, snow, or ice
from roof or eaves cannot fall directly on unit.

!

UNIT DAMAGE HAZARD

Failure to follow this caution may result in equipment
damage or improper operation.

To prevent damage to the unit, ensure that it is located
with the supports such that the unit is stable in all
circumstances including adverse conditions.

CAUTION

Make Piping Connections

Figure 2 Tie Down Knockouts

3/8-in. (9.53 mm) Dia.
Tiedown Knockouts in

Basepan(2) Places

View From Top

UNIT BASE PAN

Dimension

35 X 35 9–1/8 (231.8) 6–9/16 (166.7) 28–7/16 (722.3)

On rooftop applications, locate unit at least 6 in. (152.4 mm)
above roof surface.

TIEDOWN KNOCKOUT LOCATIONS in. (mm)

A B C

Operating Ambient

The minimum outdoor operating ambient in cooling mode is
55°F (12.78C), and the maximum outdoor operating ambient
in cooling mode is 125°F (51.67C). At line voltage of 208V
(or below) and an outdoor ambient of 120°F (48.9°C) (and
above), the compressor operates in low stage The maximum
outdoor operating ambient in heating mode is 66° F
(18.89C). 16 SEER product is approved for low ambient
cooling operation down to an ambient as low as 0°F
(−17.78 C) with low ambient accessory kits. 19 SEER
product is not approved for low ambient cooling applications.

Elevate Unit

!

UNIT DAMAGE HAZARD

Failure to follow this caution may result in equipment
damage or improper operation.

Unit must be kept free of an accumulation of water and/or
ice in the basepan.

Elevate unit per local climate and code requirements to
provide clearance above estimated snowfall level and ensure
adequate drainage of unit. If using accessory support feet,
use installation instructions from kit for installation.

CAUTION

!

PERSONAL INJURY AND ENVIRONMENTAL
HAZARD

Failure to follow this warning could result in personal
injury or death.

Relieve pressure and recover all refrigerant before system
repair or final unit disposal.

Use all service ports and open all flow−control devices,
including solenoid valves.

!

UNIT DAMAGE HAZARD

Failure to follow this caution may result in equipment
damage or improper operation.

Do not leave system open to atmosphere any longer than
minimum required for installation. POE oil in compressor is
extremely susceptible to moisture absorption. Always keep
ends of tubing sealed during installation.

If ANY refrigerant tubing is buried, provide a 6 in. (152.4
mm) vertical rise at service valve. Refrigerant tubing
lengths up to 36 in. (914.4 mm) may be buried without
further special consideration. Do not bury lines more than
36 in. (914.4 mm).

!

PERSONAL DAMAGE HAZARD

Failure to follow this warning may result in equipment
damage or improper operation.

To prevent damage to unit or service valves, observe the
following:

 Use a brazing shield.

 Wrap service valves with wet cloth or use a heat sink

material.

Outdoor units may be connected to indoor section using
accessory tubing package or field−supplied refrigerant grade
tubing of correct size and condition. For tubing requirements
beyond 80 ft/24.38 m, substantial capacity and performance
losses can occur. Following the recommendations in the
Long Line Applications Guideline will reduce these losses.
Refer to Table 1 for accessory requirements. Refer to Table 2
for field tubing diameters.

If refrigerant tubes or indoor coil are exposed to atmosphere,
they must be evacuated to 500 microns to eliminate
contamination and moisture in the system.

WARNING

CAUTION

WARNING

428 01 1703 01 3

Specifications subject to change without notice.

INSTALLATION INSTRUCTIONS R−410A Split System Heat Pumps

Table 1 − Accessory Usage

REQUIRED FOR LOW

AMBIENT COOLING APPLICATIONS

(16 SEER Product Only)

Accessory

Compressor Start Assist
Capacitor and Relay

Crankcase Heater Yes, Standard Yes, Standard No

Liquid Line Solenoid Valve No
Support Feet Recommended No Recommended

Hard Shutoff TXV
Evaporator Freeze Thermostat Yes No No
Low-Ambient Pressure Switch Ye s No No
Isolation Relay Yes No No

* For tubing line sets between 80 and 200 ft. (24.38 and 60.96 m) and/or 20 ft. (6.09 m) vertical differential, refer to Long Line Applications Guideline.

(Below 55°F / 12.8°C)

NO No No

Yes (Standard with factory

approved indoor unit)

REQUIRED FOR LONG LINE

APPLICATIONS*

See Long Line Applications

Guideline

Yes (Standard with factory

approved indoor unit)

REQUIRED FOR SEA COAST

APPLICATIONS (Withing 2

miles/3.22km)

No

Yes (Standard with factory

approved indoor unit)

Table 2 − Refrigerant Connections and Recommended Liquid and Vapor Tube Diameters (In.)

RATED VAPOR

LIQUID

UNIT SIZE

624, 924 3/8 3/8 3/4 3/4

636, 936 3/8 3/8 7/8 7/8

648, 948, 660, 960 3/8 3/8 7/8 1−1/8

* Units are rated with 25 ft. (7.6 m) of lineset. See Specification sheet for performance data when using different size and length linesets.

Notes:

1. Do not apply capillary tube or fixed orifice indoor coils to these units.

2. For Tubing Set lengths between 80 and 200 ft. (24.38 and 60.96 m) horizontal or 35 ft. (10.7 m) vertical differential 250 ft. (76.2 m) Total Equivalent Length),
refer to the Long Line Applications Guideline.

Connection Diameter Tube Diameter Connection Diameter Rated Tube Diameter

up to 80 ft. (24.38 m)*

!

WARNING

EXPLOSION HAZARD

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

Never use air or gases containing
oxygen for leak testing or operating
refrigerant compressors. Pressurized
mixtures of air or gases containing
oxygen can lead to an explosion.

4 428 01 1703 01

Specifications subject to change without notice.

INSTALLATION INSTRUCTIONS R−410A Split System Heat Pumps

Outdoor Unit Connected to Factory Approved
Indoor Unit

These outdoor units are carefully evaluated and listed with
specific indoor coils for proper system performance.

Install Adapter Tube

1. Remove plastic retainer holding outdoor piston in liquid
service valve.

2. Check outdoor piston size with matching number listed
on unit rating plate.

3. Locate plastic bag taped to unit containing adapter
tube.

4. Remove Teflon® seal from bag and install on open
end of liquid service valve. (See Fig. 3.)

5. Remove adapter tube from bag and connect threaded
nut to liquid service valve. Tighten nut finger−tight and
then with wrench an additional 1/2 turn (15 ft−lb). DO

NOT OVER TIGHTEN!

Figure 3

Liquid Service Valve

!

UNIT DAMAGE HAZARD

Failure to follow this caution may result in equipment
damage or improper operation.

Service valves must be wrapped in a heat−sinking
material such as a wet cloth while brazing.

!

UNIT DAMAGE HAZARD

Failure to follow this caution may result in equipment
damage or improper operation.

Installation of filter drier in liquid line is required.

Evacuate Refrigerant Tubing and Indoor Coil

!

UNIT DAMAGE HAZARD

Failure to follow this caution may result in equipment
damage or improper operation.

Never use the system compressor as a vacuum pump.

CAUTION

CAUTION

CAUTION

Install Liquid Line Filter Drier Indoor

Refer to Fig. 4 and install filter drier as follows:

1. Braze 5 in. (127 mm) liquid tube to the indoor coil.

2. Wrap filter drier with damp cloth.

3. Braze filter drier to 5 in. (127 mm) liquid tube from
step 1.

4. Connect and braze liquid refrigerant tube to the filter
drier.

Figure 4

Liquid Line Filter Drier

Refrigerant tubes and indoor coil should be evacuated using
the recommended deep vacuum method of 500 microns. An
alternate triple evacuation method may be used.

IMPORTANT: Always break a vacuum with dry nitrogen.

Deep Vacuum Method

The deep vacuum method requires a vacuum pump capable
of pulling a vacuum of 500 microns and a vacuum gage
capable of accurately measuring this vacuum depth. The
deep vacuum method is the most positive way of assuring a
system is free of air and liquid water. (See Fig.5)

Figure 5

5000
4500
4000
3500
3000
2500
2000

MICRONS

1500
1000

500

01234567

Deep Vacuum Graph

LEAK IN
SYSTEM

VACUUM TIGHT
TOO WET

TIGHT
DRY SYSTEM

MINUTES

A95424

Refrigerant Tubing and Sweat Connections

Use refrigerant grade tubing. Service valves are closed from
factory and ready for brazing. After wrapping service valves
with a wet cloth, braze sweat connections using industry
accepted methods and materials. Consult local code
requirements. Refrigerant tubing and indoor coil are now
ready for leak testing . This check should include all field and
factory joints.

428 01 1703 01 5

Triple Evacuation Method

The triple evacuation method should only be used when
system does not contain any water in liquid form and vacuum
pump is only capable of pulling down to 28 inches of mercury
(711mm Hg). Refer to Fig. 6 and proceed is as follows:

1. Pull system down to 28 inches of mercury (711mm Hg)
and allow pump to continue operating for an additional
15 minutes.

2. Close manifold valves or valve at vacuum pump and
shut off vacuum pump.

3. Connect a nitrogen cylinder and regulator to system
and fill with nitrogen until system pressure is 2 psig.

Specifications subject to change without notice.

INSTALLATION INSTRUCTIONS R−410A Split System Heat Pumps

4. Close nitrogen valve and allow system to stand for 1
hour. During this time, dry nitrogen will diffuse
throughout the system absorbing moisture.

5. Repeat this procedure as indicated in Figure 6.

6. After the final evacuate sequence, confirm there are no
leaks in the system. If a leak is found, repeat the entire
process after repair is made.

Figure 6

BREAK VACUUM WITH DRY NITROGEN

BREAK VACUUM WITH DRY NITROGEN

CHECK FOR TIGHT, DRY SYSTEM

(IF IT HOLDS DEEP VACUUM

Triple Evacuation Sequence

EVACUATE

WAIT

EVACUATE

WAIT

EVACUATE

CHARGE SYSTEM

Route Ground and Power Wires

Remove access panel to gain access to unit wiring. Extend
wires from disconnect through power wiring hole provided
and into unit control box.

!

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal
injury or death.

The unit cabinet must have an uninterrupted or
unbroken ground to minimize personal injury if an
electrical fault should occur. The ground may consist
of electrical wire or metal conduit when installed in
accordance with existing electrical codes.

WARNING

Connect Ground and Power Wires

Connect ground wire to ground connection in control box for
safety. Connect power wiring to contactor as shown in Fig. 7.

Figure 7 Line Power Connections

DISCONNECT
PER N. E. C. AND/OR
LOCAL CODES

CONTACTOR

FIELD POWER

WIRING

Final Tubing Check

IMPORTANT: Check to be certain factory tubing on both

indoor and outdoor unit has not shifted during shipment.
Ensure tubes are not rubbing against each other or any
sheet metal. Pay close attention to feeder tubes, making sure
wire ties on feeder tubes are secure and tight.

Make Electrical Connections

!

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal
injury or death.

Do not supply power to unit with compressor terminal box
cover removed.

Be sure field wiring complies with local and national fire,
safety, and electrical codes, and voltage to system is within
limits shown on unit rating plate. Contact local power
company for correction of improper voltage. See unit rating
plate for recommended circuit protection device.

NOTE: Operation of unit on improper line voltage constitutes
abuse and could affect unit reliability. See unit rating plate.
Do not install unit in system where voltage may fluctuate
above or below permissible limits.

NOTE: Use copper wire only between disconnect switch and
unit.

NOTE: Install branch circuit disconnect of adequate size per
NEC to handle unit starting current. Locate disconnect within
sight from and readily accessible from unit, per Section
440−14 of NEC.

6 428 01 1703 01

WARNING

FIELD GROUND

WIRING

Connect Control Wiring

This unit is capable of communication with an Observer Wall
Control, or will operate using standard 24v 2−stage
thermostat. Route 24v control wires through control wiring
grommet and connect leads to control board. When an
Observer Wall Control is available, connect DX+ and DX−
connections only. If additional grounding is needed use C
terminal. If a 2−stage thermostat is used, connect to the Y1,
Y2, W1, O, and C connections. Refer to the wiring label for
further clarification.

Use No. 18 AWG color−coded, insulated (35C minimum)
wire. If thermostat is located more than 100 ft. (30.48 m)
from unit, as measured along the control voltage wires, use
No. 16 AWG color−coded, insulated wire to avoid excessive
voltage drop.

All wiring must be NEC Class 1 and must be separated from
incoming power leads.

Use furnace transformer, fan coil transformer, or accessory
transformer for control power, 24−v/40−va minimum.

NOTE: Use of available 24−v accessories may exceed the
minimum 40−va power requirement. Determine total
transformer load and increase the transformer capacity or
split the load with an accessory transformer as required.

Final Wiring Check

IMPORTANT: Check factory wiring and field wire connections

to ensure terminations are secured properly. Check wire
routing to ensure wires are not in contact with tubing, sheet

Specifications subject to change without notice.

metal, etc.

GROUND
LUG

INSTALLATION INSTRUCTIONS R−410A Split System Heat Pumps

Compressor Crankcase Heater

When equipped with a crankcase heater and outdoor
ambient is below 40F (4.4°C), furnish power to heater a
minimum of 24 hr before starting unit. To furnish power to
heater only, set thermostat to OFF and close electrical
disconnect to outdoor unit.

A crankcase heater is required if refrigerant tubing is longer
than 80 ft. (24.38 m). Refer to the Long Line Applications
Guideline.

Install Electrical Accessories

Refer to the individual instructions packaged with kits or
accessories when installing.

Check OAT Thermistor and OCT Thermistor
Attachments

Outdoor Air Temperature (OAT) Thermistor is factory installed
by inserting the nibs on either sides of the thermistor body
through a keyhole in the bottom shelf of the control box and
locking it in place by turning it 90 degrees, such that the
spherical end of a nib faces the front of the control box.

Check to make sure the OAT is locked in place. See Fig.8.

Figure 8

The Outdoor Coil Temperature (OCT) Thermistor is factory
installed on the 3/8” diameter stub tube located on the coil
assembly. Check to make sure that it is securely attached
with the clip as shown in Fig. 9.

Figure 9

Outdoor Air Thermistor (OAT) Attachment

OAT Thermistor must be locked
in place with spherical nib end facing
towards the front of the control box.

DX+ DX- C

Outdoor Coil Thermistor (OCT) Attachment

OCT Thermistor

must be secured

tight on stub tube.

Airflow Setup with Observer Communicating
Furnace or Fan Coil

When using an Observer Communicating Wall Control and
communicating indoor equipment, airflow is automatically
selected based on equipment size. See Observer Wall
Control Installation Instructions and indoor specification sheet
for available adjustments.

Airflow Setup with Non-Communicating
Furnace or Fan Coil

Two−stage compressor operation requires two different
indoor airflow settings for proper operation. This outdoor unit
is designed for use only with an indoor blower that can be
configured for separate low−stage and high−stage airflow
(CFM) levels. Refer to Product Specifications Sheets for
recommended low−stage and high−stage indoor airflow
values.
Refer to indoor unit Installation Instructions to set the indoor
blower for the proper low−stage and high−stage airflow
values.
NOTE: Optimal comfort, efficiency, and reliability will only be
achieved when the indoor airflow is properly set for both
low−stage and high−stage operation.

START−UP

!

UNIT OPERATION AND SAFETY HAZARD

Failure to follow this caution may result in minor personal
injury, equipment damage or improper operation.

To prevent compressor damage or personal injury,
observe the following:

 Do not overcharge system with refrigerant.
 Do not operate unit in a vacuum or at negative

pressure.

 Do not disable low pressure switch in scroll compressor

applications.

 Dome temperatures may be hot.

!

PERSONAL INJURY HAZARD

Failure to follow this caution may result in personal injury.

Wear safety glasses, protective clothing, and gloves
when handling refrigerant and observe the following:

 Front seating service valves are equipped with

Schrader valves.

CAUTION

CAUTION

428 01 1703 01 7

!

ENVIRONMENTAL HAZARD

Failure to follow this caution may result in environmental
damage.

Federal regulations require that you do not vent refrigerant
to the atmosphere. Recover during system repair or final
unit disposal.

Follow these steps to properly start up the
system:

1. After system is evacuated, fully open liquid and vapor
service valves.

2. Unit is shipped with valve stem(s) front seated (closed)
and caps installed.

Specifications subject to change without notice.

CAUTION

INSTALLATION INSTRUCTIONS R−410A Split System Heat Pumps

Replace stem caps after system is opened to
refrigerant flow. Replace caps finger−tight and tighten
with wrench an additional 1/12 turn

3. Close electrical disconnects to energize system.

4. Set room thermostat or Observer Wall Control at
desired temperature. Be sure set point is below indoor
ambient temperature.

5. Set room thermostat to HEAT or COOL and fan control
to ON or AUTO mode, as desired. Operate unit for 15
minutes. Check system refrigerant charge.

Figure 10

Observer

Communicating

Wall Control

DX+

DX−

C

R

S1

S2

Observer Communicating Wall Control

Four−Wire Connection Diagram

Communicating

Variable Speed

Furnace/Fan Coil

Green

Yellow

White

Red

Optional Remote

Room Sensor

Humidifier

Connection

DX+

DX−

C

R

HUM

Green

Yellow

Two-Stage
Heat Pump

DX+

DX−

C

COM

NOTE: Wiring must conform to NEC or local codes.
NOTE: For standard thermidistat or thermostat wiring, see

Installation Instructions for those products.

Figure 11

Indoor Control

RVS Cooling

Heat/Cool

Stage 1

Heat Stage 3

Heat/Cool

Stage 2

24 VAC Hot

Dehumidify

24 VAC Comm

Humidify

RVS Heating

Outdoor

O/W2

Y1

W

Fan

DHUM

FVM Fan Coil Wiring With

Two −Stage Heat Pump

Fan Coil

O

/W2

/W1

Y/Y2

G

R

C

HUM

B

S1

S2

Y1

W1

W2

Y/Y2

G

R

H

C

Humidifier

(24 VAC)

Outdoor

Sensor

Two-Stage Heat Pump

Remove J2 Jumper

s

s

For Heat Staging

O

Y1

W1

Y2

C

Figure 12

ICP Thermostat

W2

Y1

W1

Y2

G

R

H

C

L

O/B

OD

GND

Figure 13

Note: This installation requires the daugh
ter board accessory, NAXA00101DB.
Note: This installation does not allow for
communicating feature functionality.

Variable Speed Furnace with

Two −Stage Heat Pump (Dual Fuel)

Variable Speed

Furnace

W2

Y1

W/W1

Y/Y2

G

R

DHUM

COM

HUM

OUTDOOR

SENSOR

Two-Stage
Heat Pump

Y1

W1

Y2

C

O

Non−Communicating Indoor Unit with
Observer Communicating Wall Control

Wall

Control

DX+

R

C

DX-

C

R

W2

Y1

G

Y/Y2

Non-Communicating

Indoor

NAXA00101DB

Green

Red

White

Yellow

DX+

R

C

DX-

C

R

W2

Y1

G

Y2

O





OAT

Communicating

Outdoor

OAT

Sensor

C

W1

Y1

Y2

O

Check Charge

Two−stage equipment should be charged in high−stage
compressor operation only.
Factory charge amount and desired subcooling are shown
on unit rating plate. Charging method is shown on information
plate inside unit. To properly check or adjust charge,
conditions must be favorable for subcooling charging.
Favorable conditions exist when the outdoor temperature is
between 70F and 100F (21.11C and 37.78C), and the
indoor temperature is between 70F and 80F (21.11C and

26.67C). Follow the procedure below:

8 428 01 1703 01

Specifications subject to change without notice.

INSTALLATION INSTRUCTIONS R−410A Split System Heat Pumps

Unit is factory charged for 15ft (4.57 m) of lineset. Adjust
charge by adding or removing 0.6 oz/ft of 3/8 liquid line
above or below 15ft (4.57 m) respectively.

For standard refrigerant line lengths (80 ft/24.38 m or less),
allow system to operate in cooling mode at least 15 minutes.
When operating with the Observer Wall Control in
communicating mode make sure that indoor airflow is set to
the final operating selection (Eff 325, Eff 350, Comfort,
Maximum) during charging. If conditions are favorable, check
system charge by subcooling method. If any adjustment is
necessary, adjust charge slowly and allow system to operate
for 15 minutes to stabilize before declaring a properly
charged system.

If the indoor temperature is above 80F (26.67C), and the
outdoor temperature is in the favorable range, adjust system
charge by weight based on line length and allow the indoor
temperature to drop to 80F (26.67C) before attempting to
check system charge by subcooling method as described
above.

If the indoor temperature is below 70F (21.11C), or the
outdoor temperature is not in the favorable range, adjust
charge for line set length above or below 15ft (4.57 m) only.
Charge level should then be appropriate for the system to
achieve rated capacity. The charge level could then be
checked at another time when the both indoor and outdoor
temperatures are in a more favorable range.

NOTE: The Observer Wall Control has a staging timer, to
override the staging timer for charging in high−stage create
at least a 5 degree difference between room and set point
temperatures and hold the “Cool To” button for 10 seconds
on the thermostat home screen.

NOTE: If line length is beyond 80 ft (24.38 m) or greater than
20 ft (6.10 m) vertical separation, See Long Line Applications
Guideline for special charging requirements.

Heating Tech Label

To check system operation during heating cycle, refer to the
Heating Tech Label on outdoor unit. This label indicates
whether a correct relationship exists between system
operating pressure and air temperature entering indoor and
outdoor units. If pressure and temperature do not match on
chart, system refrigerant charge may not be correct. Do not
use label to adjust refrigerant charge.

SYSTEM FUNCTIONS AND SEQUENCE OF
OPERATION

The *CH9 and *CH6 models utilize either an Observer
Communicating Wall Control or a 2-stage cooling thermostat.
With a call for first stage cooling, the outdoor fan and
low-stage compressor are energized. If low-stage cannot
satisfy cooling demand, high-stage is energized by the
second stage of the indoor thermostat. After second stage is
satisfied, the unit returns to low-stage operation until first
stage is satisfied or until second stage is required again.
When both first stage and second stage cooling are satisfied,
the compressor will shut off. When a 2-stage unit is operating
at low-stage, system vapor (suction) pressure will be higher
than a standard single-stage system or high-stage operation.
When the outdoor ambient is more than 100F (37.8C), the
outdoor fan will continue to run for one minute after
compressor shuts off, this reduces pressure differential for
easier starting in the next cycle.

With non-communicating (non-Observer) systems, with first
stage of cooling, Y1 and O are powered on; and with second
stage of cooling, Y1, Y2, and O are on. For these systems,
with first stage of heating Y1 is on and for second stage of
heating, Y1 and Y2 are on. When the reversing valve is
energized, O is powered on.

428 01 1703 01 9

Communication and Status Function Lights

Green communications (COMM) Light (Only with
Observer Communicating Wall Control)

A green LED (COMM light) on the outdoor board indicates
successful communication with the other system products.
The green LED will remain OFF until communications is
established. Once a valid command is received, the green
LED will turn ON continuously. If no communication is
received within 2 minutes, the LED will be turned OFF until
the next valid communication.

Amber Status Light (STATUS)

An amber colored STATUS light is used to display the
operation mode and fault codes as specified in the
troubleshooting section. See Table 3 for codes and
definitions.

NOTE: Only one code will be displayed on the outdoor unit
control board (the most recent, with the highest priority).

Utility Interface with Non-Communicating
Thermostat

The utility curtailment relay should be wired in the Y2
thermostat lead. This allows a power utility device to interrupt
high stage compressor operation during peak load periods. If
the utility requires control of low stage compressor operation
a second utility curtailment relay should be wired in the Y1
lead.

NOTE: Utility curtailment is not available when operating in
communicating mode. To apply utility curtailment with the
Observer Wall Control you must use a daughter board kit to
convert the control signals to standard thermostat signals.

Compressor Operation

The basic scroll design has been modified with the addition
of an internal unloading mechanism that opens a by-pass
port in the first compression pocket, effectively reducing the
displacement of the scroll. The opening and closing of the
by-pass port is controlled by an internal electrically operated
solenoid. The modulated scroll uses a single step of
unloading to go from full capacity to approximately 67%
capacity.
A single speed, high efficiency motor continues to run while
the scroll modulates between the two capacity steps.
Modulation is achieved by venting a portion of the gas in the
first suction pocket back to the low side of the compressor,
thereby reducing the effective displacement of the
compressor.
Full capacity is achieved by blocking these vents, thus
increasing the displacement to 100%. A DC solenoid in the
compressor controlled by a rectified 24 volt AC signal in the
external solenoid plug moves the slider ring that covers and
uncovers these vents. The vent covers are arranged in such
a manner that the compressor operates at approximately
67% capacity when the solenoid is not energized and 100%
capacity when the solenoid is energized. The loading and
unloading of the two step scroll is done “on the fly” without
shutting off the motor between steps.

NOTE: 67% compressor capacity translates to approximately
75% cooling capacity at the indoor coil. The compressor will
always start unloaded and stay unloaded for five seconds even
when the thermostat is calling for high−stage capacity.

Crankcase Heater Operation

The crankcase heater is de-energized when the compressor
is running. The crankcase heater is energized when the
compressor is off and the ambient is less than 42 F. When
the ambient temperature is between 65 F and 42 F the
crankcase heater is energized 30 minutes after the
compressor is turned off. When the ambient is above 65 F

Specifications subject to change without notice.

INSTALLATION INSTRUCTIONS R−410A Split System Heat Pumps

the crankcase heater remains de-energized after the
compressor is turned off.

Outdoor Fan Motor Operation

The outdoor unit control energizes the outdoor fan any time
the compressor is operating. The outdoor fan remains
energized if a pressure switch or compressor overload
should open. Outdoor fan motor will continue to operate for
one minute after the compressor shuts off when the outdoor
ambient is greater than or equal to 100F (37.8C) to allow
for easier starting during next cooling cycle.

On CCH6, HCH6 and TCH6 models - The outdoor fan motor
is a PSC type. A fan relay on the control board turns the fan
off and on by opening and closing a high voltage circuit to the
motor. It does not change speeds between low and high
stage operation.

On CCH9, HCH9 and TCH9 models − The outdoor fan is an
ECM type. The motor control is continuously powered with
high voltage. The motor speed is determined by electrical
pulses provided by the PWM outputs on the control board.
The ECM motor RPM adjusts to outdoor conditions as
described in Table 3. The PWM output can be measured
between the PWM1 and PWM2 terminals on the circuit board
with a volt meter set to DC volts.

Table 3 − Outdoor Fan Motor PWM

Outdoor Temp (DC volts, Tolerance +/− 2%)

Model

Size

924 8.72 9.35 11.90
936 9.06 10.23 11.90
948 9.91 11.04 11.90
960 10.83 11.70 11.90

Low−Stage High Stage Low & High Stage

OAT  104F/ 40C OAT  104F/ 40C OAT > 104F/ 40C

Time Delays

The unit time delays include:

 Five minute time delay to start cooling operation when

there is a call from the thermostat or Wall Control. To
bypass this feature, momentarily short and release
Forced Defrost pins or hold the “Cool To” or “Heat To”
button on the Observer Wall Control for 10 seconds.

 Five minute compressor re−cycle delay on return from

a brown−out condition.

 Two minute time delay to return to standby operation

from last valid communication (Observer
Communicating Wall Control only).

 One minute time delay of outdoor fan at termination of

cooling mode when outdoor ambient is greater than or
equal to 100F (37.8C).

 Fifteen second delay at termination of defrost before

the auxiliary heat (W1) is de−energized.

 Twenty second delay at termination of defrost before

the outdoor fan is energized.

 Seventy and sixty second compressor delays when

Quiet Shifts−2 enabled.

 There is no delay between staging from low to high

and from high to low capacity. The compressor will

change from low to high and from high to low capacity
“on the fly” to meet the demand.

DEFROST

This control offers 5 possible defrost interval times: 30, 60,
90, 120 minutes, or AUTO.

Defrost intervals are selected by dip switches on the unit
control board or by the Observer Wall Control. The Observer
Wall Control selection overrides the control board dip switch
settings.

AUTO defrost adjusts the defrost interval time based on the
last defrost time as follows:

 When defrost time <3 minutes, the next defrost

interval = 120 minutes.

 When defrost time 3 - 5 minutes, the next defrost

interval = 90 minutes.

 When defrost time 5 - 7 minutes, the next defrost

interval = 60 minutes.

 When defrost time >7 minutes, the next defrost

interval = 30 minutes.

The control board accumulates compressor run time. As the
accumulated run time approaches the selected defrost
interval time, the control board monitors the coil temperature
sensor for a defrost demand. If a defrost demand exists, a
defrost cycle will be initiated at the end of the selected time
interval. A defrost demand exists when the coil temperature

is at or below 32°F (0°C) for 4 minutes during the interval.
The defrost cycle is terminated when the coil temperature
reaches 65
OAT is > 25

as demanded by the thermostat or Wall Control.

If OAT is
only, regardless of thermostat or Wall Control demand, and

will terminate at 50
minimum of 2.5 minutes in defrost.

If the coil temperature does not reach 32
interval, the interval timer will be reset and start over.

°F (18.33°C)or 10 minutes has passed. When
°F (-3.9°C), defrost will occur in low or high stage

≤ 25°F (−3.9°C), defrost will occur in high stage

°F (10°C) coil temperature with a

°F (0°C) within the

 Upon initial power up the first defrost interval is

defaulted to 30 minutes. Remaining intervals are at
selected times.

 Defrost is only allowed to occur below 50°F (10°C)

outdoor ambient temperature.

The outdoor fan output (ODF) will remain off for 20 seconds
after termination. This delay will allow time for the system to
capture the heat from the outdoor coil and reduce the “steam
cloud” effect that may occur on transition from defrost to
heating cycle.

Defrost Hold

On a non−communicating system, if the thermostat becomes
satisfied (Y1 or Y1 and Y2) before the defrost cycle is
terminated, the control will “hold” in defrost mode and finish
the defrost cycle on the next call for heat.

On models with communicating Observer Wall Control,
defrost hold is not needed because the system will complete
the defrost cycle before shutting down the system.

10 428 01 1703 01

Specifications subject to change without notice.

INSTALLATION INSTRUCTIONS R−410A Split System Heat Pumps

Forced Defrost

On a system with non−communicating (non-Observer)
control, forced defrost can be initiated by manually shorting
the 2-pin header labeled FORCED DEFROST (see Fig 14)
on the control board for 5 seconds then releasing.

 If coil temperature is at defrost temperature of 32°F

°C), and outdoor air temperature is below 50°F

(0

°C), a full defrost sequence will occur.

(10

 If coil temperature or outdoor air temperature does not

meet the above requirements, an abbreviated 30
second defrost will occur.

Quiet Shift−2

Quiet Shift−2 is a field−selectable defrost mode which may
eliminate occasional noise that could be heard at the start
and finish of the defrost cycle. For installations using a
standard 2−stage thermostat, this feature must be enabled
by selecting the 3
board. For installations using an Observer Wall Control, it
must be enabled at the Wall Control. When activated, the
following sequence of operation occurs:
Defrost Initiation − the compressor is de−energized for 70
seconds. During this 70 second compressor off time, the
reversing valve will be energized. Once the 70 second
compressor off time has been reached, the compressor will
be energized then the outdoor fan will be de−energized at
which time the normal defrost cycle begins.
Defrost Termination
shortly before the compressor is de−energized for 60
seconds. During the compressor 60 second off time, the
reversing valve will be de−energized. Once the 60 second
compressor off time has been completed, the compressor will
be energized at which time the system will be in normal heat
mode.

Liquid−Line Accessory

In heat pump long−line applications, a liquid−line solenoid is
required to control refrigerant migration in the heating mode.
The solenoid should be installed near the outdoor unit with
the arrow facing the outdoor unit. This is the direction of flow
control. See application manual for long−line application
details.

Accessory Liquid Solenoid with Observer Communicating
Wall Control: When using the Observer Wall Control, the
liquid-line solenoid output is provided at the Y1 connection.
Connect the solenoid as shown in the wiring label diagram.
This is a 24vac output that is energized whenever the
compressor is energized. It closes, in the compressor off
mode, to prevent refrigerant migration into the unit through
the liquid−line.

On Systems with Accessory Liquid Solenoid Using a
Non−Communicating Thermostat: The liquid solenoid is
connected to the Y1 and C terminal connections. The liquid
solenoid closes, in the compressor off mode, to prevent
refrigerant migration into the unit through the liquid−line.

rd

position dip switch on the outdoor control

− The outdoor fan will be energized

TROUBLESHOOTING

If the compressor fails to operate with a cooling call, Table 4
can be used to verify if there is any damage to the
compressor windings causing system malfunction.

Table 4 − Winding Resistance

Winding Resistance At 70F +/− 20F

(21.11C +/− 11.11C)

Winding 24 36 48 60

Start

(S−C)

Run

(R−C)

1.64 1.52 1.86 1.63

1.30 0.88 0.52 0.39

Systems Communication Failure

If communication with the Observer Communicating Wall
Control will flash the appropriate fault code. (See Table 6)
Check the wiring to the wall control, indoor and outdoor units.

Model Plug

Each control board contains a model plug. The correct model
plug must be installed for or the system to operate properly
(see Table 5).

Table 5 − Model Plug

Pin Resistance

Model

Number

*CH624 HK70EZ041 18 91
*CH636 HK70EZ043 18 150
*CH648 HK70EZ045 18 220
*CH660 HK70EZ047 18 360
*CH924 HK70EZ010 5.1 120
*CH936 HK70EZ012 5.1 180
*CH948 HK70EZ014 5.1 270
*CH960 HK70EZ016 11 5.1

Model Plug

Number

(kOhms)

Pin 1−4 Pin 2−3

The model plug is used to identify the type and size of unit to
the control.
On new units, the model and serial numbers are input into
the board’s memory at the factory. If a model plug is lost or
missing at initial installation, the unit will operate according to
the information input at the factory and the appropriate error
code will flash temporarily.
A FAST® Parts replacement board contains no model and
serial information. If the factory control board fails, the model
plug must be transferred from the original board to the
replacement board for the unit to operate.
NOTE: The model plug takes priority over factory model
information input at the factory. If the model plug is removed
after initial power up, the unit will operate according to the last
valid model plug installed, and flash the appropriate fault code
temporarily.

Pressure Switch Protection

The outdoor unit is equipped with high and low pressure
switches.
If the control senses the opening of a high or low pressure
switch, it will respond as follows:

1. De-energize the appropriate compressor contactor.

2. Keep the outdoor fan operating for 15 minutes.

3. Display the appropriate fault code (see Table 6).

4. After a 15 minute delay, if there is still a call for cooling

and the LPS or HPS is reset, the appropriate
compressor contactor is energized.

5. If LPS or HPS has not closed after a 15 minute delay,

the outdoor fan is turned off. If the open switch closes
anytime after the 15 minute delay, then resume
operation with a call for cooling.

428 01 1703 01 11

Specifications subject to change without notice.

INSTALLATION INSTRUCTIONS R−410A Split System Heat Pumps

6. If LPS or HPS trips 3 consecutive cycles, the unit
operation is locked out for 4 hours.

7. In the event of a high pressure switch trip or high
pressure lockout, check the refrigerant charge outdoor
fan operation and outdoor coil for airflow restrictions.

8. In the event of a low pressure switch trip or low
pressure lockout, check the refrigerant charge and
indoor airflow.

Control Fault

If the outdoor unit control board has failed, the control will
flash the appropriate fault code. (See Table 6) The control
board should be replaced.

Brown Out Protection

If the line voltage is less than 187v for at least 4 seconds, the
appropriate compressor contactor and fan relay are
de-energized.
Compressor and fan operation are not allowed until voltage is
a minimum of 190v. The control will flash the appropriate fault
code (see Table 6)

230 V Brown Out Protection Defeated:

The brownout feature can be defeated if needed for severe
noisy power conditions. This defeat should always be a last
resort to solving the problem. Defeat can be initiated through
the forced defrost pins as follows:
The brownout toggle is accomplished by shorting the defrost
pins from power up with the OAT and OCT sensor connector
removed.

After 3 seconds, the status of the force defrost short and the
OAT/OCT as open will be checked. If correct, then the
brownout will be toggled.

 Status code 6 shows the brownout is disabled.

 Status code 5 shows the brownout is active.

After the brownout defeat is set, power down and reinstall the
OAT/OCT sensor and remove the short from the forced
defrost pins. As long as the short on the forced defrost
remains, the OAT and OCT faults will not be cleared. The
code will continue to be flashed.

The control is shipped with the brownout active. The change
in status is remembered until toggled to a new status. A
power down/power up sequence will not reset the status. It
may be necessary to do the toggle twice to cycle to the
desired state of the defeat.

230V Line (Power Disconnect) Detection

If there is no 230v at the compressor contactor(s) when the
indoor unit is powered and cooling demand exists, the
appropriate error code is displayed (see Table 6). Verify that
the disconnect is closed and 230v wiring is connected to the
unit.

Compressor Voltage Sensing

The control board input terminals labeled VS and L2 (see
Fig. 14) are used to detect compressor voltage status, and
alert the user of potential problems. The control continuously
monitors the high voltage on the run capacitor of the
compressor motor. Voltage should be present any time the
compressor contactor is energized, and voltage should not
be present when the contactor is de−energized.

Contactor Shorted Detection

If there is compressor voltage sensed when there is no
demand for compressor operation, the contactor may be
stuck closed or there is a wiring error. The control will flash
the appropriate fault code.

12 428 01 1703 01

Compressor Thermal Cutout

If the control senses the compressor voltage after start−up,
and is then absent for 10 consecutive seconds while cooling
demand exists, the thermal protector is open. The control
de−energizes the compressor contactor for 15 minutes, but
continues to operate the outdoor fan.

The control Status LED will flash the appropriate code shown
in Table 6. After 15 minutes, with a call for low or high stage
cooling, the compressor contactor is energized. If the thermal
protector has not reset, the outdoor fan is turned off. If the call
for cooling continues, the control will energize the
compressor contactor every 15 minutes. If the thermal
protector closes, (at the next 15 minute interval check), the
unit will resume operation. If the thermal cutout trips for three
consecutive cycles, then unit operation is locked out for 4
hours and the appropriate fault code is displayed.

No 230V at Compressor

If the compressor voltage is not sensed when the
compressor should be starting, the appropriate contactor
may be stuck open or there is a wiring error. The control will
flash the appropriate fault code. Check the contactor and
control box wiring.

Troubleshooting units for proper switching
between low & high stages

Check the suction pressures at the service valves. Suction
pressure should be reduced by 3−10% when switching from
low to high capacity.

NOTE: The liquid pressures are very similar between low and
high stage operation so liquid pressure should not be used
for troubleshooting.

Compressor current should increase 20−45% when switching
from low to high stage. The compressor solenoid, when
energized in high stage, should measure 24vac across pin
numbers PL5−2 HI and PL5−5 C. When the compressor is
operating in low stage the 24v DC compressor solenoid coil
is de−energized. When the compressor is operating in high
stage, the 24v DC solenoid coil is energized. The solenoid
plug harness that is connected to the compressor has an
internal rectifier that converts the 24v AC signal to 24v DC.

NOTE: DO NOT INSTALL A PLUG WITHOUT AN
INTERNAL RECTIFIER.

Unloader Test Procedure

The unloader is the compressor internal mechanism,
controlled by the DC solenoid, that modulates between high
and low stage. If it is suspected that the unloader is not
working, the following methods may be used to verify
operation.

1. Operate the system and measure compressor
amperage. Cycle the unloader on and off at 30 second
plus intervals at the Wall Control (from low to high
stage and back to low stage). Wait 5 seconds after
staging to high before taking a reading. The
compressor amperage should go up or down at least
20 percent.

2. If step one does not give the expected results, remove
the solenoid plug from the compressor and, with the
unit running and the Wall Control (or Thermostat)
calling for high stage, test the voltage output at the
plug with a DC voltmeter. The reading should be 24
volts DC.

3. If the correct DC voltage is at the control circuit molded
plug, measure the compressor unloader coil
resistance. The resistance should be 330 or 1640
ohms depending on unloader coil supplier. If the coil
resistance is infinite or is grounded, the compressor

Specifications subject to change without notice.

must be replaced.

INSTALLATION INSTRUCTIONS R−410A Split System Heat Pumps

MAJOR COMPONENTS
2-Stage Control

The 2−stage control board controls the following functions:
— Compressor high and low stage operation
— Outdoor fan motor operation
— Compressor external protection
— Pressure switch monitoring
— Time delays
— Defrost Control

Field Connections

On models with non−communicating (Thermostat other than
Observer Wall Control) system, the 2−stage control receives
24vac low−voltage control system inputs through the Y1, and
Y2 connections located at the bottom of the control board
(see Fig. 14). The OD units can be controlled using a
standard 2-stage thermostat or Observer Wall Control.

2-Stage Compressor

The 2−stage compressor contains motor windings that
provide 2−pole (3500 RPM) operation. Refer to Table 4 for
correct winding resistance.

Compressor Internal Relief

The compressor is protected by an internal pressure relief
(IPR) which relieves discharge gas into compressor shell
when differential between suction and discharge pressures
exceeds 550 − 625 psig The compressor is also protected by
an internal overload attached to motor windings.

Compressor Control Contactor

The contactor has a 24 volt coil. The electronic control board
controls the operation of the appropriate contactor.

TEMPERATURE THERMISTORS

Thermistors are electronic devices which sense temperature.
As the temperature increases, the resistance decreases.
Thermistors are used to sense outdoor ambient (OAT) and
coil temperature (OCT). Refer to Fig. 15 for resistance values
versus temperature. If the outdoor ambient or coil thermistor
should fail, the control will flash the appropriate fault code

(see Table 6.)

IMPORTANT

factory mounted in the final locations. Check to insure
thermistors are mounted properly per Fig.8 and Fig.9.

: Outdoor air thermistor and coil thermistor are

Thermistor Sensor Comparison

The control continuously monitors and compares the outdoor
air temperature sensor and outdoor coil temperature sensor
to ensure proper operating conditions. The comparison is:
— If the outdoor air sensor indicates 10F (5.56C) warmer
than the coil sensor (or) the outdoor air sensor indicates
20F (11.1C) cooler than the coil sensor, the sensors are
out of range.
— If the sensors are out of range, the control will flash the
appropriate fault code as shown in Table 6.

Failed Thermistor Default Operation

Factory defaults have been provided in the event of failure of
outdoor air thermistor and/or coil thermistor.

OAT Thermistor must be locked in place with
spherical nib end facing towards the front of
the control box.

Final Checks

IMPORTANT: Before leaving job, be sure to do the following:

1. Ensure that all wiring is routed away from tubing and
sheet metal edges to prevent rub-- through or wire
pinching.

2. Ensure that all wiring and tubing is secure in unit
before adding panels and covers. Securely fasten all
panels and covers.

3. Tighten service valve stem caps to 1/12--turn past
finger tight.

4. Leave Owner’s Manual with owner. Explain system
operation and periodic maintenance requirements
outlined in manual.

Care and Maintenance

For continuing high performance and to maintain warranty
coverage, periodic maintenance must be performed on this
equipment. Frequency of maintenance may vary depending
upon geographic areas, such as coastal applications. See
Owner’s Manual for information.

428 01 1703 01 13

Specifications subject to change without notice.

INSTALLATION INSTRUCTIONS R−410A Split System Heat Pumps

Figure 14 Two −Stage Control Board

14 428 01 1703 01

Specifications subject to change without notice.

INSTALLATION INSTRUCTIONS R−410A Split System Heat Pumps

Table 6 − Status Codes

OPERATION FAULT

Standby – no call for unit operation None On solid, no flash Normal operation
Low Stage Cool/Heat Operation None 1, pause Normal operation
High Stage Cool/Heat Operation None 2, Pause Normal operation
Brown out protection is Disabled None 5, pause User mode selection, see instructions for more detail
Brown out protection is Active None 6, Pause User mode selection, see instructions for more detail

System Communications

Failure

Invalid Model Plug 25

High Pressure

Switch Open

Low Pressure

Switch or Discharge Temp

Switch Open

Control Fault 45

AMBER LED

FLASH CODE

16

31*

32*

Possible Cause and Action

Communication with Observer Wall Control lost. Check wiring to

Observer Wall Control, indoor and outdoor units

Control does not detect a model plug or detects and invalid model

plug. Unit will not operate without correct model plug.

High pressure switch trip. Check refrigerant charge, outdoor fan

operation and coils for airflow restrictions.

Low pressure switch or discharge temperature switch trip. Check

refrigerant charge and indoor air flow

Outdoor unit control board has failed. Control board needs to be

replaced.

Brown Out

(230 v)

No 230v at Unit 47

Outdoor Air Temp Sensor

Fault

Outdoor Coil Sensor Fault 55

Thermistors out

of range

Low Stage

Thermal Cutout

High Stage

Thermal Cutout

Contactor Shorted 73

No 230V at

Compressor

Low Stage Thermal

Lockout

High Stage Thermal

Lockout

Low Pressure Lockout 83

High Pressure

Lockout

*Sequence: Compressor contactor is de−energized and outdoor fan is energized for up to 15 minutes. If demand still exists, control will energize compressor.

46

53

56

71*

72*

74

82

82

84

Line Voltage <187v for at least 4 seconds. Compressor and fan

operation not allowed until voltage > 190v. Verify line voltage.

There is not 230v at the contactor when indoor unit is powered and
cooling/heating demand exists. Verify the disconnect is closed and
230v wiring is connected to the unit.

Outdoor air sensor not reading or out of range. Ohm out sensor and
check wiring

Coil sensor not reading or out of range. Ohm out sensor and check
wiring

Improper relationship between coil sensor and outdoor air sensor.
Ohm out sensors and check wiring.

Compressor operation detected then disappears while low stage
demand exists. Possible causes are internal compressor overload trip
or start relay and capacitor held in circuit too long (if installed)

Compressor operation detected then disappears while high stage
demand exists. Possible causes are internal compressor overload trip
or start relay and capacitor held in circuit too long (if installed)

Compressor voltage sensed when no demand for compressor
operation exists. Contactor may be stuck closed or there is a wiring
error.

Compressor voltage not sensed when compressor should be starting.
Disconnect may be open or contactor may be stuck open or there is a
wiring error.

Thermal cutout occurs in three consecutive low/high cycles. Low stage
locked at for 4 hours or until 24v power recycled.

Thermal cutout occurs in three consecutive low/high cycles. High
stage locked out for 4 hours or until 24v power recycled.

Low pressure switch trip has occurred during 3 consecutive cycles.
Unit operation locked out for 4 hours or until 24v power recycled.

High pressure switch trip has occurred during 3 consecutive cycles.
Unit operation locked out for 4 hours or until 24v power recycled.

Figure 15 Resistance vs Temperature Chart

428 01 1703 01 15

THERMISTOR CURVE

90

80

70

60

50

40

30

20

RESISTANCE (KOHMS)

10

0

0

(-17.77)

20

(-6.67)

Specifications subject to change without notice.

40

(4.44)

TEMPERATURE °F (°C)

60

(15.56)

80

(26.67)

100

(37.78)

120

(48.89)

INSTALLATION INSTRUCTIONS R−410A Split System Heat Pumps

R−410A QUICK REFERENCE GUIDE

• R−410A refrigerant operates at 50% − 70% higher pressures than R−22. Be sure that servicing equipment and
replacement components are designed to operate with R−410A.

• R−410A refrigerant cylinders are rose colored.

• Recovery cylinder service pressure rating must be 400 psig, DOT 4BA400 or DOT BW400.

• R−410A systems should be charged with liquid refrigerant. Use a commercial type metering device in the

manifold hose when charging into suction line with compressor operating.

• Manifold sets should be 750 psig high−side and 200 psig low−side with 520 psig low−side retard.

• Use hoses with 750 psig service pressure rating.

• Leak detectors should be designed to detect HFC refrigerant.

• R−410A, as with other HFC refrigerants, is only compatible with POE oils.

• Vacuum pumps will not remove moisture from oil.

• Do not use liquid line filter−driers with rated working pressures less than 600 psig.

• Do not install a suction line filter−drier in liquid line.

• POE oils absorb moisture rapidly. Do not expose oil to atmosphere.

• POE oils may cause damage to certain plastics and roofing materials.

• Wrap all filter−driers and service valves with wet cloth when brazing.

• A liquid line filter−drier is required on every unit.

• Do not use with an R−22 TXV.

• If indoor unit is equipped with an R−22 TXV, it must be changed to an R−410A TXV.

• Never open system to atmosphere while it is under a vacuum.

• When system must be opened for service, break vacuum with dry nitrogen and replace all filter−driers. Evacuate to 500 microns

prior to recharging.

• Do not vent R−410A into the atmosphere.

• Do not use capillary tube indoor coils.

• Observe all WARNINGS, CAUTIONS, NOTES, and bold text.

16 428 01 1703 01

Specifications subject to change without notice.

Copyright 2013 International Comfort Products,

Lewisburg, TN 37091 USA