Carrier 10 SEER SPLIT-SYSTEM 38YCW Installation And Start-up Instructions Manual

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Installation and Start-Up Instructions

NOTE: Read the entire instruction manual before starting the

installation.
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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 willresultinsevere
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.

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(es) with a suitable warning label. Electrical shock can
cause personal injury or death.

INTRODUCTION AND RECOMMENDATIONS

NOTE: In some cases noise has been traced to improper instal-

lation 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-tubediametersare appropriate to
capacity of unit.

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

38YCW

10 SEER Split-System

Heat Pump

A98525

Fig. 1—Model 38YCW

.

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 refrigerant 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 refrigerant 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 and/or in the Check Charge section of this
Instruction.

IMPORTANT: Maximum liquid-line size is 5/8-in. O.D. for all
residential applications including long line applications.

IMPORTANT: Always install a liquid-line filter drier. Refer to
Product Data Digest for appropriate part number. Obtain filter
drier from your distributor or branch.

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 Catalog No. 533-80020 Printed in U.S.A. Form 38YCW-3SI Pg 1 2-02 Replaces: 38YCC-4SI

Avoid contact between tubing and structureNOTE:

OUTDOOR WALL INDOOR WALL

CAULK

LIQUID TUBE

C

INSULATION

THROUGH THE WALL

HANGER STRAP

(AROUND VAPOR

TUBE ONLY)

1″ MIN.

SUSPENSION

VAPOR TUBE

JOIST

INSULATION

VAPOR TUBE

LIQUID TUBE

A94028

Fig. 2—Connecting Tubing Installation

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.

3

⁄8″D. (9.53) TIEDOWN

A

KNOCKOUTS (2) PLACES

B

A94199

Dimensions (In.)

UNIT

SIZE

018–030 22-1/2 x 22-1/2 3-11/16 18-1/8 14-3/8
036–060 30 x 30 6-1/2 23-1/2 20

MINIMUM

MOUNTING-PAD

DIMENSIONS

TIEDOWN KNOCKOUT LOCATIONS

ABC

Fig. 3—Mounting Unit to Pad

Step 4—Operating Ambients

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—Elevate Unit

Step 2—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. 3
to determine base-pan size and knockout-hole location.

On rooftop applications, mount on level platform or frame 6 in.
above roof surface. 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.
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.

Accumulation of water and ice in base pan may cause
equipment damage.

In areas where prolonged freezing temperatures are encountered,
elevate unit per local climate and code requirements to provide
clearance above estimated snowfall level and ensure adequate
drainage of unit.

Step 6—Check Indoor And Outdoor AccuRater® Piston

Check indoor-coil piston to see if it matches the required piston
shown on outdoor unit-rating plate. If it does not match, replace
indoor-coil piston with piston shipped with outdoor unit. The
piston shipped with outdoor unit is correct for any approved
indoor-coil combination.

Remove indoor-coil piston if unit is to be installed on system
with a TXV-metering device.

Step 7—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 3 in.
long. 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.

2

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

UNIT

SIZE

018, 024 3/8 3/8 3/4 3/4 3/4 3/4
030, 036 3/8 3/8 3/4 3/4 3/4 7/8
042, 048 3/8 3/8 7/8 7/8 7/8 1-1/8

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

NOTES:

1. Tube diameters are for lengths up to 50 ft. For tubing lengths greater than 50 ft, consult Long Line section of the Application Guideline.

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

Connection Diameter Tube Diameter Connection Diameter Tube Diameter Connection Diameter Tube Diameter

LIQUID VAPOR VAPOR (LONG LINE)

Step 8—Make Piping Connections

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.

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. For
lengths above 36 in., consult your local distributor.

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 50 ft
length or 20 ft vertical differential, 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 diam­eters.

REFRIGERANT TUBING
Connect tubing to fittings on outdoor unit vapor- and liquid-

service valves. (See Table 1.) Use refrigerant-grade tubing. Refer
to appropriate section below for type of service valves installed on
unit.

SWEAT CONNECTION

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

STRAINER

SWEAT/FLARE ADAPTER

A97512

Fig. 4—Liquid-Service Valve with Sweat-Adapter

Tube

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.

Step 9—Make Electrical Connections

To avoid valve damage while brazing, service valves must be
wrapped in a heat-sinking material such as a wet cloth.

1. Remove plastic retainer holding outdoor piston in liquid­service valve.

2. Locate adapter tube shipped with unit.

3. Install strainer in adapter tube and connect tube to service
valve. (See Fig. 4.)

4. Connect refrigerant tubing to fittings on outdoor-unit vapor­and liquid-service valves.

5. 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

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 or phase imbalance (3 phase)
may fluctuate above or below permissible limits.

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

3

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.

only, set thermostat to OFF and close electrical disconnect to
outdoor unit. A crankcase heater is required if refrigerant tubing is
longer than 50 ft.

ROUTE GROUND AND POWER WIRES
Remove access panel and control box to gain access to unit wiring.

Extend wires from disconnect through power-wiring hole provided
and into unit-control box.

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. 5.

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

CONTACTOR

FIELD POWER

WIRING

3 PHASE ONLY

BLUE

Step 11—Install Electrical Accessories

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

Step 12—Start-Up

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.

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.

FIELD GROUND

WIRING

GROUND
LUG

A94025

Fig. 5—Line Power Connections

CONNECT CONTROL WIRING
Route 24v control wires through control-wiring grommet and

connect leads to control wiring. Refer also to Installation Instruc­tions packaged with thermostat.

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.

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 metal, and so
forth.

Step 10—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

Do not vent refrigerant to atmosphere. Recover during system
repair or final unit disposal.

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.

Follow these steps to properly start up the system:

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, as desired. Operate unit for a minimum of 15
minutes. Check system refrigerant charge.

•3-phase scroll compressors are rotation sensitive.

•A flashing LED on phase monitor indicates reverse rotation.

(See Fig. 7 and Table 2.)
This will not allow contactor to be energized.

•Disconnect power to unit and interchange 2 field-wiring
leads on unit contactor.

Step 13—Check Charge

Factory charge is shown on unit-rating plate. To check charge in
cooling mode, refer to Cooling-Only Procedure on unit wiring and
charging label.

4

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
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.

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.

Step 14—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.

Table 2—Phase-Monitor LED Indicators

LED STATUS
OFF

FLASHING Reversed phase

ON Normal

No call for compressor

operation

Fig. 7—Phase-Monitor Control

A00010

5

OTHER

HP THERMOSTAT

24 VAC HOT

24 VAC COM

HEAT STAGE 2
COOL/HEAT

STAGE 1
INDOOR FAN

RVS COOLING
EMERGENCY

HEAT

NOTE: Remove wires from crimp nut in indoor fan coil
when installing outdoor thermostat.

IMPORTANT: When using outdoor thermostat, W2 must be
energized when requesting supplemental heat.

W2

FA, FB, FC,

FD, FF, FH

FAN COIL

R

C

Y

G

O

E

W3

W2

HEAT
PUMP

R

C

E

G

THERMOSTAT

R

C

W2

Y

O

ONE

OUTDOOR

ODT

OTHER

NON-PROGRAMMABLE

HP THERMOSTAT

24 VAC HOT

24 VAC COM

HEAT STAGE 2
COOL/HEAT

STAGE 1

INDOOR FAN

RVS COOLING

EMERGENCY
HEAT

R

C

W

Y

G

O

E

FA, FB, FC,

FD, FF

FAN COIL

R

C

W2

G

HEAT
PUMP

R

C

W2

Y

O

CARRIER

PROGRAMMABLE

THERMOSTAT

MODEL HP

24 VAC HOT

INDOOR FAN

HEAT STAGE 2
COOL/HEAT

STAGE 1
RVS COOLING

NOT USED

24 VAC COM
NOT USED
TROUBLE

OPTIONAL
OUTDOOR
SENSOR
CONNECTION

CARRIER

PROGRAMMABLE

THERMOSTAT

MODEL HP

24 VAC HOT

INDOOR FAN

HEAT STAGE 2
COOL/HEAT

STAGE 1
RVS COOLING

NOT USED

24 VAC COM
NOT USED
TROUBLE

OPTIONAL
OUTDOOR
SENSOR
CONNECTION

NOTE: Remove wires from crimp nut in indoor fan coil
when installing outdoor thermostat.

IMPORTANT: When using outdoor thermostat, W2 must be
energized when requesting supplemental heat.

FA, FB, FC, FD, FF, FH

R

G

W/W1

Y/Y2

O/W2

Y1/W2

C

B
L

S1

S2

R

G

W/W1

Y/Y2

O/W2

Y1/W2

C

B

L

S1

S2

40FKA

FK4C

FAN COIL

FAN COIL

DH

R
G

W1
W2

Y/Y2

O

C

Y1

W3

R

G

W2

E

C

HEAT
PUMP

J1 JUMPER

J2 JUMPER

HEAT
PUMP

CARRIER

PROGRAMMABLE

THERMOSTAT

MODEL HP

24 VAC HOT

R

W2

Y

O

C

W2

OUTDOOR

THERMOSTAT

R

Y

O

C

ONE

ODT

INDOOR FAN

R

G

Y/Y2

C

B

S1

S2

W/W1

Y/Y2

O/W2

Y1/W2

S1

S2

EHR

EHR

EHR

L

HEAT STAGE 2
COOL/HEAT

STAGE 1
RVS COOLING

NOT USED

24 VAC COM
NOT USED
TROUBLE

OPTIONAL
OUTDOOR
SENSOR
CONNECTION

CARRIER

PROGRAMMABLE

THERMOSTAT

MODEL HP

24 VAC HOT

INDOOR FAN

HEAT STAGE 2
COOL/HEAT

STAGE 1
RVS COOLING

NOT USED

24 VAC COM
NOT USED
TROUBLE

OPTIONAL
OUTDOOR
SENSOR
CONNECTION

NOTE: Remove wires from crimp nut in indoor fan coil
when installing outdoor thermostats.

IMPORTANT: When using outdoor thermostats, W2 must be
energized when requesting supplemental heat.

W/W1

O/W2

Y1/W2

Fig. 6—Typical 24v Circuit Connections

6

R

G

C

B

L

FA, FB, FC,

FD, FF, FH

FAN COIL

FA, FB, FC,

FD, FF, FH

FAN COIL

IF AVAILABLE

*

W3

R

G

W2

E

C

R

G

W2

E

W3

C

*
*

*

HEAT
PUMP

HEAT

PUMP

OUTDOOR

THERMOSTATS

ODT

R

W2

Y

O

ODT

C

R

W2

Y

O

C

TWO

A01384

WIRING DIAGRAM NOTES:

1. CARRIER THERMOSTAT-WIRING DIAGRAMS ARE
ONLY ACCURATE FOR MODEL NUMBERS BEGINNING
WITH TSTAT_______.

2. WIRING MUST CONFORM TO NEC OR LOCAL CODES.

3. SOME UNITS ARE EQUIPPED WITH PRESSURE
SWITCH(ES), TEMPERATURE SWITCH, OR 5–MINUTE
COMPRESSOR-CYCLE PROTECTION. CONNECT 24V
FIELD WIRING TO FACTORY-PROVIDED STRIPPED
LEADS.

4. THERMOSTATS ARE FACTORY CONFIGURED WITH
5-MINUTE COMPRESSOR-CYCLE PROTECTION AND
4-CYCLES-PER-HR LIMIT. SEE THERMOSTAT­INSTALLATION INSTRUCTIONS FOR DETAILS.

5. TO STAGE ELECTRIC-RESISTANCE HEAT, CONSULT
OUTDOOR THERMOSTAT-INSTALLATION INSTRUC­TIONS.

6. UNDERLINED LETTER ON DUAL TERMINAL INDI­CATES ITS USAGE.
FOR EXAMPLE: O/W2 MEANS O; O/W2MEANS W2

7. OUTDOOR-TEMPERATURE SENSOR MUST BE AT­TACHED IN ALL DUAL-FUEL INSTALLATIONS. JUMPER
WIRE BETWEEN O/W2 AND L THERMOSTAT TERMINALS
MUST BE PRESENT.

8. Y1 AND O CONNECTIONS TO 2–STAGE FURNACES
MAY NOT EXIST OR MAY ONLY BE A WIRE RATHER
THAN A SCREW TERMINAL.

SEQUENCE OF OPERATION

NOTE: Defrost-control board is 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. On 3-phase models with scroll compressors, the units are
equipped with a phase monitor to detect if the incoming power is
correctly phased for compressor operation. If phasing is correct,
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.

NOTE: If the phasing is incorrect, the contactor will not be
energized. To correct the phasing, interchange any 2 of the 3
power connections on the field side.

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. If

phasing is correct, circuit R-Y energizes contactor, starting
outdoor-fan motor and compressor. Circuit R-G energizes indoor­blower 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
sequencer, bringing on first bank of supplemental electric heat and
providing electrical potential to second heater sequencer (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 sequencer. All heaters and motors should stop.

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

Quiet Shift

→

Quiet Shift is a field-selectable defrost mode, which will eliminate
occasional noise that could be heard at the start of the defrost cycle
and restarting of heating cycle. It is selected by placing DIP switch
3 (on defrost board) in ON position.

When Quiet Shift switch is placed in ON position, and a defrost is
initiated, the following sequence of operation will occur. Revers­ing valve will energize, compressor will turn off for 30 sec, then
turn back on to complete defrost. At the start of heating cycle after
conclusion of defrost mode, reversing valve will de-energize, the
compressor will turn off for another 30 sec, and the fan will turn
off for 40 sec, before starting in the heating mode.

T2 C C O

OF2

CESO130076–00

→
→

O R W

2

Y C

SPEEDUP

Defrost

P1

J1

DFT

Speedup
Pins

DFT

T1 Y

30

60

INTERVAL TIMER

120

90

60

30

P3

ON

OFF

QUIET

SHIFT

Quiet
Shift

Defrost interval
DIP switches

Fig. 8—Defrost Control

The defrost control is a time/temperature control which includes a
field-selectable time period (DIP switch 1 and 2 on the board)
between defrost cycles of 30, 60, 90, or 120 minutes (factory set at
90 minutes).

To initiate a forced defrost, two options are available depending on
the status of the defrost thermostat.

If defrost thermostat is closed, speedup pins (J1) must be shorted
by placing a flat head screwdriver in between for 5 sec and
releasing, to observe a complete defrost cycle. When the Quiet
Shift switch is selected, compressor will be turned off for two 30
sec intervals during this complete defrost cycle as explained
previously. When Quiet Shift switch is in factory default OFF
position, a normal and complete defrost cycle will be observed.

If defrost thermostat is in open position, and speedup pins are
shorted (with a flat head screwdriver) for 5 sec and released, a
short defrost cycle will be observed (actual length is dependent
upon the selected Quiet Shift position). When Quiet Shift switch is
in ON position, the length of defrost is 1 minute (30 sec
compressor off period followed by 30 sec of defrost with com­pressor operation). On return to heating operation, compressor will
again turn off for an additional 30 sec and the fan for 40 sec. When
the Quiet Shift is in OFF position, only a brief 30 sec cycle will be
observed.

OF1

A91444

7

If it is desirable to observe a complete defrost in warmer weather,
the thermostat must be closed as follows:

1. Turn off power to outdoor unit.

2. Disconnect outdoor fan motor lead from OF2 on control
board. (See Fig. 8.) Tape 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).

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

5. Turn off power to outdoor and reconnect fan motor lead to
OF2 on control board after above forced defrost cycle.

Step 1—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.

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.

Copyright 2002 CARRIER Corp. • 7310 W. Morris St. • Indianapolis, IN 46231 38ycw3si

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 Catalog No. 533-80020 Printed in U.S.A. Form 38YCW-3SI Pg 8 2-02 Replaces: 38YCC-4SI