Carrier 38YCB User manual

38YCB(P), 38AYB, 38BYB
Split-System
Heat Pump
Model Specific Instructions
NOTE: Read the entire instruction manual before starting the
installation. Refer to Split-System Heat Pump Common Installa-
tion and Start-Up Practices (included in this packet).
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 thor-
oughly 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 word DANGER, WARNING, or CAU-
TION. These words are used with the safety-alert symbol. DAN-
GER 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.
Before installing, modifying, or servicing system, main elec-
trical 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
Step 1—Mount Unit to Pad
Refer to Fig. 1 for pad dimensions and dimensions needed to
mount unit to pad.
Step 2—Refrigerant Tubing
Refer to Fig. 2 for refrigerant tube dimensions and connections.
Step 3—Mechanical Connection (38YCP Model)
1. Remove plastic retainer holding outdoor piston and piston
retainer in the liquid service valve. Connect and tighten the
liquid service valve adapter to the valve body prior to
assembling ferrule/lock nut. (See Fig. 3.)
2. Cut tubing to the correct length, deburr and size as necessary,
making sure tube ends are square. If a large burr is evident, the
ID and OD must be deburred to allow the tube to bottom in
valve.
3. Remove lock nut and ferrule from plastic bag taped to service
panel. (See Fig. 4.) Remove the lock nut and ferrule from
liquid service valve adapter. (See Fig. 3.)
If undersized, damaged, or elliptically shaped tubing is used
when making connection, leaks could result.
4. Slide the lock nut and ferrule onto each tube. (See Fig. 5.)
5. Apply a few drops of refrigerant oil to the ferrule and valve
threads and adapter threads to reduce assembly torque and
assist sealing.
6. Insert tube end into the service valve or adapter until it
bottoms.
7. Push the ferrule into place and hand tighten the nut until an
increase in torque is felt.
8. Mark the nut and tube and tighten 1-1/2 turns from the mark.
(See Fig. 6.) Keep the tube bottomed in the valve and adapter
while tightening nut.
Fig. 1—Mount Unit to Pad
UNIT SIZE MIN. PAD
DIM. (IN.)
TIEDOWN KNOCKOUT
LOCATIONS
A
(In.) B (In.) C (In.)
38YCB(P)018-030
38AYB018
38BYB018 22-1/2 X 22-1/2 3-11/16 18-1/8 14-3/8
38YCB(P)036-060
38AYB024-060
38BYB024-060 30 X 30 6-1/2 23-1/2 20
A94199
C
B
A
3⁄8″D. (9.53) TIEDOWN 
KNOCKOUTS (2) PLACES

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. 563-809 Printed in U.S.A. Form 38YCB-2SI Pg 1 6-96 Replaces: 38YCB-1SI

NOTE: A backup wrench on the hex part of the suction valve
fitting is required while tightening.
The tube end must stay bottomed in the service valve during
final assembly to ensure proper seating, sealing, and rigidity.
MECHANICAL FITTING REPAIR
To replace damaged ferrule or tubing, proceed as follows.
1. Attach gages to service valves.
2. Close liquid service valve and operate unit in cooling mode to
pump refrigerant charge into condenser coil.
3. When suction pressure reaches 5 psig, shut unit off. Do not
operate unit in a vacuum.
4. Close suction service valve and recover refrigerant in tubing.
5. Back-off locknut and ferrule onto tube.
6. Remove damaged part of tubing using tubing cutter. Repeat
installation procedure previously outlined using new ferrule.
7. Evacuate tubing set and indoor coil. Check for leaks.
8. Open service valves or recharge unit. Check refrigerant
charge.
Fig. 2—Refrigerant Tube Dimensions/Connections
UNIT SIZE LIQUID TUBE VAPOR TUBE
Conn Dia Tube Dia Conn Dia Tube Dia
018, 024 3/8 3/8 5/8 5/8
030, 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
Tube diameters are for lengths up to 50 ft. For tubing lengths greater than 50
ft, consult your local distributor.
A93578
LIQUID LINE CONN
FIELD CONTROL 
SUPPLY CONN
7⁄8″ DIA HOLE

FIELD POWER 
SUPPLY CONN
7⁄8″ DIA HOLE WITH 
1 1⁄8″ DIA KNOCKOUT
AND 1 3⁄8″ DIA
KNOCKOUT
AIR DISCHARGE
SUCTION LINE CONN
Fig. 3—Liquid Service Valve Mechanical Fitting
Assembly (38YCP Model)
A94030
PISTON BODY
PISTON
PISTON RETAINER
LOCK NUT
LIQUID SERVICE
VALVE ADAPTER
FERRULE
Fig. 4—Suction Service Valve with Mechanical
Adapter (38YCP Model)
A92120
VALVE FITTING
FERRULE
LOCK NUT
Fig. 5—Lock Nut/Ferrule Positioning A92121
FERRULE LOCK NUT
TUBING
Fig. 6—Proper Marking of Valve Assembly
A92122
LOCK NUT
MARK ON LOCK NUT 
AND TUBE
TUBING
2

NOTE: A thermostatic expansion valve (TXV) is required on all
38BYB units. Step 4 refers to the installation of the TXV.
Step 4—Remove Indoor AccuRater® Piston and Install
TXV
For proper unit operation and reliability, units must be
installed with a field-supplied hard shut-off TXV. Do not
install with evaporator coils having capillary tube metering
devices or piston.
After removing existing AccuRater from indoor coil, install
field-supplied bi-flow hard shut-off TXV kit. (See Fig. 7 and 8.)
For TXV kit part number and charging instruction, refer to TXV
label in your unit. If the indoor unit (fan coil) comes factory
equipped with a bi-flow hard shut-off TXV, no TXV change is
required.
Install TXV kit to indoor coil as follows:
1. Install suction tube adapter.
2. Install liquid flare-to-sweat adapter.
3. Connect external equalizer tube to fitting on suction tube
adapter.
4. Position sensing bulb on horizontal portion of suction tube
adapter. Secure using supplied hardware.
5. Insulate bulb after installation. (See Fig. 8.)
6. Leak check all connections.
Fig. 7—Typical TXV Installation A88382
THERMOSTATIC
EXPANSION
VALVE
EQUALIZER
TUBE
SENSING
BULB
COIL
Fig. 8—Positioning of Sensing Bulb A81032
2 O'CLOCK
10 O'CLOCK
SENSING BULB
STRAP
SUCTION TUBE
8 O'CLOCK 4 O'CLOCK
7⁄8IN. OD & SMALLER LARGER THAN 7⁄8IN. OD
3

A94328
SERVICE TRAINING
Packaged Service Training programs are an excellent way to increase your
knowledge of the equipment discussed in this manual, including:
 • Unit Familiarization • Maintenance
 • Installation Overview • Operating Sequence
A large selection of product, theory, and skills programs is available, using popular
video-based formats and materials. All include video and/or slides, plus companion
book.
Classroom Service Training plus "hands-on" the products in our labs can mean
increased confidence that really pays dividends in faster troubleshooting, fewer
callbacks. Course descriptions and schedules are in our catalog.
CALL FOR FREE CATALOG 1-800-962-9212
[ ] Packaged Service Training [ ] Classroom Service Training
Copyright 1996 CARRIER Corp. • 7310 W. Morris St. • Indianapolis, IN 46231 38ycb2si
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. 563-809 Printed in U.S.A. Form 38YCB-2SI Pg 4 6-96 Replaces: 38YCB-1SI