Carrier 25HBR user guide manual

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25HBR

Base™ Series R-22 Heat Pumps

Sizes 018 to 060, 1 1/2 to 5 Tons

Installation and Start-Up Instructions

NOTE: Read the entire instruction manual before starting the

installation.

This symbol → indicates a change since the last issue.

Fig. 1—25HBR Dense Grille Unit

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 National
Electrical Code (NEC) for special requirements.

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

Understand the signal words DANGER, WARNING, and CAU­TION. These words are used with the safety-alert symbol. DAN­GER identifies the most serious hazards which will result in severe
personal injury or death. WARNING signifies hazards which

A05340

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.

ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
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. Electrical shock can
cause personal injury or death.

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, and so forth
where unit operation sounds may disturb customer.

2. Ensure that vapor- and liquid-tube diameters are appropriate to
capacity of unit.

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. 2.)

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 that comes in direct contact with tubing.
(See Fig. 2.)

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

9. When necessary, use hanger straps which are 1 in. wide and
conform to shape of tubing insulation. (See Fig. 2.)

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

When outdoor unit is connected to factory-approved indoor unit,
outdoor unit contains system refrigerant charge for operation with
indoor unit of the same size when connected by 15 ft of

.

field-supplied or factory-accessory tubing. For proper unit opera­tion, check refrigerant charge using charging information located
on control box cover.

IMPORTANT: Maximum liquid line size is 3/8-in. O.D. for all
residential applications including long line.

IMPORTANT: Always install a liquid line filter drier on any
system using existing field service line sets and or existing indoor

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.

Book 1 4
Tab 5a 5a

PC 101 Printed in U.S.A. Catalog No. 25HBR-1SI Pg 1 10-05 Replaces: New

Avoid contact between tubing and structureNOTE:

OUTDOOR WALL INDOOR WALL

3/8-IN. DIA TIEDOWN
KNOCKOUTS IN
BASEPAN (2) PLACES

CAULK

INSULATION

THROUGH THE WALL

HANGER STRAP

(AROUND VAPOR

TUBE ONLY)

1″ (25.4 mm)MIN.

SUSPENSION

LIQUID TUBE

VAPOR TUBE

JOIST

INSULATION

VAPOR TUBE

LIQUID TUBE

A94028

Fig. 2—Connecting Tubing Installation

coil or fan coil units. Always use a filter drier on burnout unit
replacements.

INSTALLATION

Step 1—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 service
panel. It contains information needed to properly install unit.
Check rating plate to be sure unit matches job specifications.

Step 2—Install On A Solid, Level Mounting Pad

If conditions or local codes require the unit be attached to pad,
tiedown bolts should be used and fastened through knockouts
provided in unit base pan. Refer to unit mounting pattern in Fig. 3
to determine base pan size and knockout hole location.

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 above 5 mph may require
wind baffles to achieve adequate defrost. Consult Low Ambient
Guideline for wind baffle construction.

NOTE: Unit must be level to within ± 2° (± 3/8 in./ft) per
compressor manufacturer specifications.

Step 3—Clearance Requirements

When installing, allow sufficient space for airflow clearance,
wiring, refrigerant piping, and service. Allow 30-in. clearance to
service end of unit and 48 in. above unit. For proper airflow, a 6-in.

A

Dimensions (In.)

MINIMUM

MOUNTING-PAD

DIMENSIONS

26x26 9-1/8 4-7/16 21-1/4

31-1/2 x 31-1/2 9-1/8 6-9/16 24-11/16

35x35 9-1/8 6-9/16 28-7/16

TIEDOWN KNOCKOUT LOCATIONS

AB C

Fig. 3—Mounting Unit to Pad

clearance on 1 side of unit and 12 in. on all remaining sides must
be maintained. Maintain a distance of 24 in. between units.
Position so water, snow, or ice from roof or eaves cannot fall
directly on unit.

On rooftop applications, locate unit at least 6 in. above roof
surface.

Step 4—Operating Ambient

The minimum outdoor operating ambient in cooling mode is 55°F,
and the maximum outdoor operating ambient in cooling mode is
125°F. The maximum outdoor operating ambient in heating mode
is 66°F.

Step 5—Install TXV

NOTE: Applies to non-TXV indoor units only. If installing a

rated and approved indoor coil without a factory installed R-22
TXV, remove and replace the fixed orifice or Puron TXV
expansion device with an R-22 TXV.
The thermostatic expansion valve is specifically designed to
operate with R-22. Do not use a Puron TXV. An existing Puron
TXV must be replaced with a factory approved TXV specifically
designed for R-22. Refer to Product Data Digest for the appropri­ate TXV kit number.

UNIT OPERATION HAZARD
Failure to follow this caution may result in equipment damage
or improper operation.
For proper unit operation and reliability, units must be
installed with field supplied hard shutoff TXV. Do not install
with evaporator coils having capillary tube metering devices
or pistons.

IMPORTANT: If not factory installed, the TXV should be
mounted as close to the indoor coil as possible and in a vertical,
upright position. Avoid mounting the inlet tube vertically down.
Valve is more susceptible to malfunction due to debris if inlet tube
is facing down. A factory approved filter drier must be installed in
the liquid line.

INSTALLING TXV IN PLACE OF PISTON

1. Pump system down to 2 psig and recover refrigerant.

2

C

B

A05177

2. Remove hex nut from piston body. Use backup wrench on fan
coils.

3. Remove and discard factory installed piston. Be sure Teflon®
seal is in place.

4. Reinstall hex nut. Finger tighten nut plus 1/2 turn.

NOTE: If the piston is not removed from the body, TXV will not
function properly.

EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage
or improper operation.
To prevent damage to the unit, use a brazing shield and wrap
TXV with wet cloth or use heat sink material.

5. Install TXV on indoor coil liquid line. Sweat swivel adapter to
inlet of indoor coil and attach to TXV outlet. Use backup
wrench to avoid damage to tubing or valved. Sweat inlet of
TXV, marked IN, to liquid line. Avoid excessive heat which
could damage valve.

6. Install vapor elbow with equalizer adapter to suction tube of
line set and suction connection to indoor coil. Adapter has a
1/4 in. male connector for attaching equalizer tube.

10 O'CLOCK

2 O'CLOCK

SENSING BULB

STRAP

8. Install TXV with 3/8-in. copper tubing through small hole in
service panel. Use wrench and backup wrench, to avoid
damage to tubing or valve, to attach TXV to distributor.

9. Reinstall TXV support clamp (removed in item 3).

10. Attach TXV bulb to vapor tube inside cabinet, in same
location as original was when removed, using supplied bulb
clamps (nylon or copper). See Fig. 4 for correct positioning of
sensing bulb.

11. Route equalizer tube through suction connection opening
(large hole) in fitting panel and install fitting panel in place.

12. Sweat inlet of TXV, marked IN to liquid line. Avoid excessive
heat which could damage valve.

13. Install vapor elbow with equalizer adapter to vapor line of line
set and vapor connection to indoor coil. Adapters has a 1/4-in.
male connector for attaching equalizer tube.

14. Connect equalizer tube of TXV to 1/4-in. equalizer fitting on
vapor line adapter. Use backup wrench to prevent damage to
equalizer fitting.

15. Proceed with remainder of unit installation.

Step 6—Check Defrost Thermostat

Check defrost thermostat to ensure it is properly located and
securely attached. There is a liquid header with a brass distributor
and feeder tube going into outdoor coil. At the end of 1 of the
feeder tubes, there is a 3/8-in. O.D. stub tube approximately 2 in.
long. (See Fig. 5.) The defrost thermostat should be located on stub
tube. Note that there is only 1 stub tube used with liquid header,
and on most units it is the bottom circuit.

SUCTION TUBE

4 O'CLOCK

7⁄

IN. OD

8

A81032

7

⁄

IN. OD & SMALLER

8

8 O'CLOCK

LARGER THAN

Fig. 4—Positioning of Sensing Bulb

7. Connect equalizer tube of TXV to 1/4-in. equalizer fitting on
vapor line adapter.

8. Attach TXV bulb to horizontal section of suction line using
clamps provided. Insulate bulb with field supplied insulation
tape. See Fig. 4 for correct positioning of sensing bulb.

9. Proceed with remainder of unit installation.

REPLACING TXV ON PURON INDOOR COIL

1. Pump system down to 2 psig and recover refrigerant.

2. Remove coil access panel and fitting panel from front of
cabinet.

3. Remove TXV support clamp using a 5/16-in. nut driver. Save
the clamp.

4. Remove Puron TXV using a backup wrench on flare connec­tions to prevent damage to tubing.

5. Using wire cutters, cut equalizer tube off flush with vapor tube
inside cabinet.

6. Remove bulb from vapor tube inside cabinet.

7. Braze equalizer stub-tube closed. Use protective barrier as
necessary to prevent damage to drain pan.

IMPORTANT: Route the equalizer tube of R-22 TXV through
suction line connection opening in fitting panel prior to replacing
fitting panel around tubing.

FEEDER TUBE

STUB TUBE

DEFROST
THERMOSTAT

Fig. 5—Defrost Thermostat Location

Step 7—Make Piping Connections

PERSONAL INJURY AND UNIT DAMAGE 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 to avoid personal injury or death.
Use all service ports and open all flow control devices,
including solenoid valves.

A97517

3

Table 2—Accessory Usage

ACCESSORY

Crankcase Heater Standard (if required) Yes Yes No

Evaporator Freeze Thermostat No Yes No No

Accumulator Standard No Yes Standard

Compressor Start-Assist

Capacitor and Relay

MotorMaster® Control,

Low-Ambient Pressure Switch

Liquid-Line Solenoid Valve

Ball-Bearing Fan Motor No Yes† No No

* For tubing line sets between 80 and 200 ft horizontal or 20 ft vertical differential (Total Equivalent Length), refer to Application Guideline and Service Manual.
† Required for low-ambient controller (full-modulation feature) and MotorMaster® Control only.

or

Support Feet Yes Recommended No Recommended

or

Hard-Shutoff TXV

REQUIRED FOR

APPLICATIONS IN

SNOW BELT REGION

No Yes Yes No

No Yes No No

No No

REQUIRED FOR

LOW-AMBIENT

APPLICATIONS

(BELOW 55°F)

REQUIRED FOR

LONG-LINE

APPLICATIONS*

See Long-Line

Application

Guideline

REQUIRED FOR

SEA COAST APPLICATIONS

(WITHIN 2 MILES)

No

UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage
or improper unit operation.
If ANY refrigerant tubing is buried, provide a 6 in. vertical
rise at service valve. Refrigerant tubing lengths up to 36 in.
may be buried without further special consideration.

UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage
or improper unit 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 accessory­tubing package or field supplied refrigerant grade tubing of correct
size and condition. For tubing requirements beyond 80 ft, substan­tial capacity and performance losses can occur. Following the
recommendations in the Residential Split System Long-Line
Application Guideline will reduce these losses. Refer to Table 1
for field tubing equivalent line length. Refer to Table 2 for
accessory requirements.

There are no buried line applications greater than 36 in.

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.

UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage
or improper operation.
To avoid valve damage while brazing, service valves must be
wrapped in a heat sink material such as a wet cloth.

Remove plastic retainer holding outdoor piston in liquid service
valve and connect sweat/flare adapter provided to valve. (See Fig.

6.) Connect refrigerant tubing to fittings on outdoor unit vapor­and liquid service valves. Service valves are closed from factory
and ready for brazing. After wrapping service valve with a wet
cloth, tubing set can be brazed to service valve using either silver
bearing or non-silver bearing brazing material. Consult local code
requirements. Refrigerant tubing and indoor coil are now ready for
leak testing. This check should include all field and factory joints.

PISTON BODY

PISTON

PISTON
RETAINER

SWEAT/FLARE ADAPTER

OUTDOOR UNIT CONNECTED TO FACTORY APPROVED
INDOOR UNIT

Outdoor unit contains correct system refrigerant charge for opera­tion with indoor unit of same size when connected by 15 ft of
field-supplied or factory accessory tubing and a factory-supplied
filter drier. Check refrigerant charge for maximum efficiency.

REFRIGERANT TUBING AND SWEAT CONNECTIONS

Connect vapor tubing to fittings on outdoor unit vapor service
valves. (See Table 1.) Connect liquid tubing to adapter tube on
liquid service valve. Use refrigerant grade tubing.

A05226

Fig. 6—Liquid Service Valve

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.

4

Table 1—Refrigerant Connections And Recommended Liquid- And Vapor-Tube Diameters (In.)

UNIT
SIZE

018, 024 3/8 3/8 5/8 5/8

030 3/8 3/8 3/4 3/4
036 3/8 3/8 3/4 3/4

042, 048 3/8 3/8 7/8 7/8

060 3/8 3/8 7/8 1-1/8

NOTES:

1. Tube diameters are for total equivalent lengths up to 80 ft. For tubing lengths greater than 80 ft horizontal or 20 ft vertical differential, consult the Application Guideline
and Service Manual.

2. Do not apply capillary tube indoor coils to these units.

Connection Diameter Tube Diameter Connection Diameter Tube Diameter

LIQUID VAPOR

INSTALL LIQUID LINE FILTER DRIER INDOOR

UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage
or improper operation.
To avoid performance loss and compressor failure, installa­tion of filter drier in liquid line is required.

Refer to Fig. 7 and install filter drier as follows:

1. Braze 5-in. liquid tube to the indoor coil.

2. Wrap filter drier with damp cloth.

3. Braze filter drier to 5 in. long liquid tube from step 1.

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

EVACUATE REFRIGERANT TUBING AND INDOOR COIL

Step 8—Make Electrical Connections

ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
To avoid 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 circuit­protection 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.

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. Failure to follow this warning can result in an
electric shock, fire, or death.

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. 8.

Fig. 7—Liquid Line Filter Drier

A05227

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

CONTACTOR

FIELD POWER

WIRING

FIELD GROUND

WIRING

GROUND
LUG

Fig. 8—Line Power Connections

CONNECT CONTROL WIRING

Route 24v control wires through control wiring grommet and
connect leads to control wiring. See Thermostat Installation
Instructions for wiring specific unit combinations. (See Fig. 9.)

5

A91056

ODT

EHR

SHR





HP THERMOSTAT

24 VAC HOT



24 VAC COM








HEAT STAGE 2





COOL/HEAT

STAGE 1

INDOOR FAN

RVS COOLING



EMERGENCY


HEAT







HEAT 
PUMP

R

C

W2

Y

G

O

E

TYPICAL
FAN COIL

R

C

W2

E

W3

G

IF AVAILABLE

*




*

*

*

LEGEND

24-V FACTORY WIRING

24-V FIELD WIRING

FIELD SPLICE CONNECTION

OUTDOOR THERMOSTAT

EMERGENCY HEAT RELAY

SUPPLEMENTAL HEAT RELAY




R

C

W2

Y

O

(See Thermostat Installation Instructions for wiring specific unit combinations.)

Fig. 9—Generic Wiring Diagram

Use No. 18 AWG color coded, insulated (35°C minimum) wire. If
thermostat is located more than 100 ft from unit, as measured
along the control voltage wires, use No. 16 AWG color coded 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, 24v/40va minimum.

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

IMPORTANT: Check factory wiring and wire connections to
ensure terminations are secured properly. Check wire routing to
ensure wires are not in contact with tubing, sheet metal, and so
forth.

Step 9—Compressor Crankcase Heater

When equipped with a crankcase heater, 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.

A02325

Step 10—Install Electrical Accessories

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

Step 11—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.

6

PERSONAL INJURY HAZARD
Failure to follow this caution may result in personal injury.
To prevent personal injury wear safety glasses, protective
clothing, and gloves when handling refrigerant and observe
the following:

•Back-seating service valves are not equipped with Schrader
valves. Fully back seat (counterclockwise) valve stem before
removing gage-port cap.

•Front-seating service valves are equipped with Schrader
valves.

ENVIRONMENTAL HAZARD
Failure to follow this caution may result in environmental
damage.
Federal Regulations require that you do not vent refrigerant to
atmosphere. Recover during system repair or final unit
disposal.

Follow these steps to properly pump down a system and avoid
negative suction pressure.

1. Fully back seat (open) liquid- and vapor-tube service valves.

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

SEQUENCE OF OPERATION

NOTE: Defrost control board may be equipped with 5-minute
lockout timer that may be initiated upon any interruption of power.

With power supplied to indoor and outdoor units, transformer is
energized.

COOLING

On a call for cooling, thermostat makes circuits R-O, R-Y, and
R-G. Circuit R-O energizes reversing valve, switching it to cooling
position. Circuit R-Y energizes contactor, starting outdoor fan
motor and compressor circuit. R-G energizes indoor unit blower
relay, starting indoor blower motor on high speed.

When thermostat is satisfied, its contacts open, de-energizing the
contactor and blower relay. Compressor and motors should stop.

NOTE: If indoor unit is equipped with a time delay relay circuit,
the blower runs an additional 90 sec to increase system efficiency.

HEATING

On a call for heating, thermostat makes circuits R-Y and R-G.
Circuit R-Y energizes contactor, starting outdoor fan motor and
compressor. Circuit R-G energizes indoor blower relay, starting
blower motor on high speed.

Should temperature continue to fall, R-W2 is made through
second-stage room thermostat bulb. Circuit R-W2 energizes a
relay, bringing on first bank of supplemental electric heat and
providing electrical potential to second heater relay (if used). If
outdoor temperature falls below setting of outdoor thermostat
(field installed option), contacts close to complete circuit and bring
on second bank of supplemental electric heat.

When thermostat is satisfied, its contacts open, de-energizing
contactor and relay. All heaters and motors should stop.

DEFROST

The defrost control is a time/temperature control which includes a
field selectable (quick-connects located at board edge) time period
between defrost cycles (30, 60, or 90 minutes), factory set at 90
minutes.

The electronic timer and defrost cycle start only when contactor is
energized and defrost thermostat is closed.

Defrost mode is identical to cooling mode except that outdoor fan
motor stops and second-stage heat is turned on to continue
warming conditioned space.

To initiate defrost, the defrost thermostat must be closed. This can
be accomplished as follows:

1. Turn off power to outdoor unit.

2. Disconnect outdoor fan motor lead from OF2 on control
board. (See Fig. 10.) Tape lead to prevent grounding.

3. Restart unit in heating mode, allowing frost to accumulate on
outdoor coil.

4. After a few minutes in heating mode, liquid-line temperature
should drop below closing point of defrost thermostat (ap­proximately 30°F).

5. Short between speedup terminals with a flat-blade screw­driver. (See Fig. 10.) This reduces the timing sequence to
1/256th of original time. (See Table 3.)

6. When you hear reversing valve change position, remove
screwdriver immediately; otherwise, control will terminate
normal 10-minute defrost cycle in approximately 2 sec.

NOTE: Length of defrost cycle is dependent upon length of time
it takes to remove screwdriver from test pins after reversing valve
has shifted.

7. Unit will remain in defrost for remainder of defrost cycle time
or until defrost thermostat reopens at approximately 80°F coil
temperature of liquid line.

8. Turn off power to outdoor unit and reconnect fan motor lead
to OF2 on control board. (See Fig. 10.)

Step 12—Check Charge

Factory charge is shown on unit rating plate. To check charge in
cooling mode, refer to Cooling Only Procedure. To check charge
in heating mode, refer to Heating Check Chart Procedure.

COOLING ONLY PROCEDURE

NOTE: If superheat- or subcooling-charging conditions are not
favorable, charge must be weighed in accordance with unit rating
plate ± 0.6 oz/ft of 3/8-in. liquid line above or below 15 ft
respectively.

EXAMPLE:

To calculate additional charge required for a 25–ft line set:

25 ft – 15 ft = 10 ft X 0.6 oz/ft=6ozofadditional charge

Units installed with cooling mode TXV require charging with the
subcooling method.

1. Operate unit a minimum of 10 minutes before checking
charge.

2. Measure liquid service-valve pressure by attaching an accurate
gage to service port.

3. Measure liquid-line temperature by attaching an accurate
thermistor type or electronic thermometer to liquid line near
outdoor coil.

4. Refer to unit rating plate for required subcooling temperature.

7

A05332

Table 3—Defrost Control Speedup-

Timing Sequence

PARAMETER

30–minute cycle 27 33 7 sec
50–minute cycle 45 55 12 sec
90–minute cycle 81 99 21 sec
10–minute cycle 9 11 2 sec

5 minutes 4.5 5.5 1 sec

MINIMUM

(MINUTES)

MAXIMUM

(MINUTES)

SPEEDUP

(NOMINAL)

Fig. 10—Defrost Control

5. Refer to Table 4. Find the point where required subcooling
temperature intersects measured liquid service-valve pressure.

6. To obtain required subcooling temperature at a specific
liquid-line pressure, add refrigerant if liquid-line temperature
is higher than indicated or reclaim refrigerant if temperature is
lower. Allow a tolerance of ± 3°F.

HEATING CHECK CHART PROCEDURE

To check system operation during heating cycle, refer to the
Heating Check Chart on outdoor unit. This chart 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 chart to adjust refrigerant charge.

Table 4—Required Liquid-Line Temperature (°F)

LIQUID

PRESSURE AT

SERVICE VALVE

(PSIG)

134 71 66 61 56
141 74 69 64 59
148 77 72 67 62
156 80 75 70 65
163 83 78 73 68
171 86 81 76 71
179 89 84 79 74
187 92 87 82 77
196 95 90 85 80
205 98 93 88 83
214 101 96 91 86
223 104 99 94 89
233 107 102 97 92
243 110 105 100 95
253 113 108 103 98
264 116 111 106 101
274 119 114 109 104
285 122 117 112 107
297 125 120 115 110
309 128 123 118 113
321 131 126 121 116
331 134 129 124 119
346 137 132 127 122
359 140 135 130 125

NOTE: When charging is necessary during heating season,

charge must be weighed in accordance with unit rating plate ± 0.6
oz/ft of 3/8-in. liquid line above or below 15 ft respectively.

EXAMPLE:

To calculate additional charge required for a 25–ft line set:

25 ft – 15 ft = 10 ft X 0.6 oz/ft=6ozofadditional charge

Step 13—Final Checks

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

1. Securely fasten all panels and covers.

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

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

4. Fill out Dealer Installation Checklist and place in customer
file.

CARE AND MAINTENANCE

For continuing high performance and to minimize possible equip­ment failure, periodic maintenance must be performed on this
equipment.

Frequency of maintenance may vary depending upon geographic
areas, such as coastal applications.

REQUIRED SUBCOOLING

TEMPERATURE (°F)

5 101520

Copyright 2005 CARRIER Corp. • 7310 W. Morris St. • Indianapolis, IN 46231 25hbr1si

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.

Book 1 4
Tab 5a 5a

PC 101 Printed in U.S.A. Catalog No. 25HBR-1SI Pg 8 10-05 Replaces: New