Carrier 38AB Dimensions and installation guide

Carrier
and Service Instructions
38AB.AD
024thro 084
Air-Cooled Condensing Units
Table 1 — Dimensions
UNIT
38AD 38AD
024 028
38AD
034
38AD
044
38AB
054
38AB
064
38AB
084
DIMENSIONS (Ft—in
i.)
Length
A
o
1
CO
12-10%
24- -4
24-4
Width
B
3-11%
4-10%
6- 0‘/ 4
3-11%
4-10%
6- 0%
Height w/o Legs
C
2- 4%
3- r/ 8
3- 2
2- 4%
3- r/ 8
3- 1%
Leg Height
D
1-0 or 2-0
1 —6 or 2—2
1- 8
1 -4 or 2-0
1-6 or 2-2
1 _8 or 2—
Mtg Holes
< J
O
1
sC
o
1
0- 1% 2—%
0- 1%«
0- 1%6
0- 1%
Corner Legs
Ik
3- 8% 3- 8%
4- 7%
5- 7%
00
1
CO
4- 7%
5- 9%
o
i
o
o
1
o
o
1
o
2-%
o
1
o
o
I
o
o
I
o
Middle Legs
Ik
3-10 1 3-10
00
1
xr
5- 7%
CO
1
o
CO
1
XT
5~ioy 2
L
3-3%
3- 7% 6
9-4%
M
9-4%
00
o
5-3%
N
|
1 -
-
9-5%
CONNECTIONS (in
.)
Suction (ODM)
l-%
2-%
2-V
Liquid (ODM)
%
7 /s
1 —%
OPENINGS (in.)
Suction
E
2-%
4
5
(2)5
Liquid
F
1- % I 1- %
1 i- %
2
2-%
3
7/
Control (4 holes)
G
%
1 — 5 4
1
k
Power
H
3-%
5
s-%
(2)3%
*Unit 38AB084 has two suction connections
AIR FLOW
GUSSET -pf
REMOVABLE , n o . HINGED CONTROL
TOP COVER BOX DOOR
\oNLY) 2 NI t Y) REQUIRED OVERHEAD
FL0W*\Ef/ F / E Al 5 ff ACE
38AD024
028, 034
A ^tt
w
i Ckii
mm
'4-0 (BOTH SIDES)
4-0 *.,
(BOTH SIDES)"
-REMOVABLE
END PANELS
HINGED ACCESS DOOR- REQUIRED OVERHEAD
CONTROL BOXi ~ AIR SPACE
AIR FLOW
GUSSET P"
A>
;_HINGED POWER
: BOX DOOR
‘ 4-0"(BOTH SIDES)
38AD044
4 1 - o"——
(BOTH SIDES)
REMOVABLE
END PANELS
AIR FLOW
BOTTOM PANELREMOVABLE REAR
OPENINGPANEL
f Px^Removable top requi
Ilf( COVER OVER!
FLOW AIR SI
HINGED AIR
control V
box covers
/^REMOVABLE TOP REQUIRED
/ COVER OVERHEAD
^^ • AIR FLOW AIR SPACE
38AB054,
064, 084
O' I? \i
4-0 X;
(BOTH SIDES)
'X 4 - 0 "
(BOTH SIDES)
AIR FLOW THRU
CONDENSER
11 SPACE FOR SERVICE
AND AIR FLOW
Certified dimension drawings are available on request
Fig. 1 — Dimensions
©Carrier Corporation 1972
Form 38AD-6SI

f^GOJ^G
Lift unit at points G,H, J, and K (Fig. 2). Use
eyebolts and washers supplied in parts package. Do
not sling unskidded unit Skidded unit may be
slung, provided sling does not contact unit sides.
Do not roll unskidded unit on pipes or wooden
pilings.
Fig. 2 — Weight Distribution and Lifting Points
Table 2 - Weight Distribution
UNIT
WEIGHT (lb)
Total
Leg Location
A
B C
D
E
F
38AD024 1750
175 175 575
575
125 125
38AD028
1900 178
178 521
565
207 251
38AD034
2300 263
263 767
767 120
120
38AD044
3200 ,
359 359 770
810
441
461
38AB054
3145 j
180 605 607
181
- -
38AB064
3830
245 712
714
244
- -
38AB084
4960
327 913
913
327
-
-
SKID REMOVAL
Remove the four bolts (each section) holding
top frame in place and lift frame from unit
(38AD024 thru 044 and 38AB054,064 units).
Compressor (with coil) Section — Raise and block
up one side of unit 8 inches. Remove the three
exposed hold-down bolts from base skid. Lower
unit and repeat on opposite side.
Coil (only) Section (38AB054.064 and 084) -
Raise and block up one end of unit 8 inches.
Remove the two exposed hold-down bolts from
base skid. Lower unit and repeat on opposite end.
ERECTING AND INTEGRATING ONE UNIT
Position Units 38AD028,044 and 38AB054,
064,084 so air flow is unrestricted on all sides and
on top (Fig. 1).
38AD024,034: any side except compressor end
may be installed against a wall if high leg setting is
used and other three sides are unrestricted.
Place 38AB and 38AD units on high leg setting if
accessory damper is used.
Erect Uniteuswrgklegs and gussets attached to unit
base skid(s) or frame. Adjust all corner legs to
desired height before attaching to unit.
38AD024,028,034 AND 044 UNITS - Block up
or suspend unit. With field-supplied bolts, bolt
corner leg and angle gusset to each corner of unit.
Bolt two center legs to bottom of unit where
compressor and coil sections meet. Lower unit.
38AB054,064 AND 084 UNIT - Block up or
suspend compressor (with coil) section. Bolt corner
leg and angle gusset to each corner at coil end. Bolt
two center legs to compressor end. Allow one set
of holes to project out past compressor section.
Bolt two center legs to bottom of unit where
compressor and coil sections meet. Lower unit.
Block up or suspend coil (only) section. Bolt
two corner legs and angle gussets to coil return
bend end. Butt coil (only) section against com¬
pressor compartment, allowing coil to rest on leg
projections. Remove top cover on compressor
compartment and bolt sections together at legs and
sides.
Table 3 — Legs and Gussets Provided
QUANTITY
38AB
38AD
Corner
Leg
Center
Leg
Angle
Gusset
Parts
Pkg*
-
024,028
034
4 2
4
1
-
044_
4 2
-
1
054,064
-
-
4
__
1
084
-
4
-
4
1
*Parts packages in units contain al! mounting fasteners required
for attaching legs and gussets
38AD | 38AD 38AD 38AD
38AB
-1
38AB
38AB
UNIT
024 | 028
034 044
054
064 084
A(in.)
16 16
18 1 -*
16 18 .
20
B(in.)
24 :
24
26 j 20
24 26 ;
28
*Only 044 units use one-piece legs
Fig. 3 — Legs and Gussets
2

Compressor Mounting
38AD024,028,034 UNITS - As shipped, com¬
pressor is held down by special self-locking bolts
and plain lockwashers. After unit is installed,
remove the self-locking bolts one at a time and
reassemble with flanged washers and neoprene
snubbers as shown in Fig. 4. Special flanged wash¬
ers and neoprene snubbers are shipped in a cloth
bag tied to one of the compressor feet. Tighten all
four bolts. Then, loosen each until the flanged
washer can be moved sidewise.
38AD044, 38AB054,064 AND 084 UNITS (com¬
pressors are mounted on a common support
channel) — Remove the four shipping bolts from
mounting channels prior to start-up.
Fig. 4 — Compressor Mounting
(38AD024,028 and 034)
Fan Thermostat — Route the thermostat control
bulb and capillary (located in compressor section)
thru grommeted hole in compressor section base
pan. Do not kink capillary. Position bulb in inlet
ah stream and secure to inlet ah flange adjacent to
compressor section. Use clamp and screw provided
in parts package.
If accessory head pressure control damper
section is used, secure bulb to air inlet side of
damper. Use hole in damper frame.
Integrate Unit (38AB054.064 and 084 only) —
Connect refrigerant piping between the two sec¬
tions, using materials furnished with unit. Arrange
discharge and liquid lines as shown in Fig. 5 and
braze as indicated.
Electrically connect unit control box and junc¬
tion box on coil (only) section by using flexible
fan conduit furnished in the unit. Use the mating,
quick-connect, polarized plugs furnished in the two
sections to make the wire connections.
Motormaster® (32 Series) Head Pressure Controller
— Refer to MOTORMASTER Instructions shipped
with this accessory, plus the following information.
Control box and sensor location is shown in
Fig. 6.
Electrical connections are shown in Fig. 7.
Refer to unit label diagram as requhed. On 200-,
208- and 230-volt units, outdoor fan motor no. 1
(OFMj), located nearest the compressor, may be
used with MOTORMASTER without modification.
For 460- and 575-volt units, refer to Table 4 for
field-supplied components needed with
MOTORMASTER.
Fig. 6 - MOTORMASTER Control Box
and Sensor Location
3

FROM FAN
CONTACTOR
200, 208, 230
OR 460 VOLTS
200, 208-, AND 230-VOLT UNITS
.^ffV vBRN a BRN.
MOTOR
SUITABLE FOR
USE WITH
32LT
'MOTORMASTER
SPEED
CONTROLLER*
200-, 230“V RATED
CONTROLLER
*Use 230-volt controller with 200-,208- or 230-volt motors
Fig. 7 — Motormaster® Electrical Connections
Table 4 — Components Required for
MOTORMASTER Use
UNIT
MODEL
RUN
CAPACITOR
TRANS¬
FORMER
MOTOR
38AD024
600
100
HC96LH020
HT01AH951
HT01AH959
HC46VL220 or
HC46VL221
38AD028
38AD034
38AD044
38AB054
38AB064
38AB084
600
HC96LH030
HT01AH952
HC52TE230
100
HT01AH954
REFRIGERANT PIPING
Refrigerant Line Sizes will depend on length of
piping required between condensing unit and evap¬
orator. Consideration must be given to liquid lift
and to compressor oil return. Refer to Part 3 of
Carrier System Design Manual for line sizing
information and Fig. 8 for recommended piping
details.
Single Pumpout Control — All units are factory
wired to operate on single pumpout control and
require a field-supplied liquid line solenoid valve,
sized for minimum pressure drop, to be installed
immediately ahead of each expansion valve. If unit
is to be used with a chiller, wiring modifications
may be necessary. Refer to 38AB Application
Data, Chilled Water Applications.
Refrigerant Drier and Moisture Indicator — A
filter-drier(s) and a liquid-moisture indicator are
shipped with unit for field installation. Refer to
Fig. 9 for typical recommended piping arrange¬
ments and to Table 5 for physical data on driers.
Receiver — No receiver is provided with unit. It is
recommended that one not be used.
Piping Procedure — Do not remove plastic dust
plugs from suction and liquid line stubs in com¬
pressor compartment until piping connections are
ready to be made. Pass nitrogen or other inert gas
thru piping while brazing, to prevent formation of
copper oxide.
NOTES 2 D as used in 8D etc, indicates the pipe diameter size as a measure of length
1 Lower split first on, last off 3 TXVE indicates Thermostatic Expansion Valve Equalizer Connection
Fig. 8 — Typical Piping Connections for Face Split Coils
77 7
4

Fig. 9 — Recommended Filter-Drier(s)
and Sight Glass Locations
Table 5 — Filter-Drier Replacement Parts and Data
UNIT
FILTER-DRIER
Part No.
Qty
Conn.
Size ;
Replacement
Part No.
Core
Qty
38AD024
KH43LE1 23
1
% :
Same 0
38AD028 |
KH43LE121 2
s /»
Same
0
38AD034 j
KH43LE 121
2 %
Same
0
38AD044 j
KH49EA030
1
X
KH29EZ050*
2
38AB054 !
KH49EA120
1
l 1 /*
KH29EZ050*
2
38AB064 |
KH49EA120
1
i l / 8
KH29EZ050*
2
38AB084
KH49EA040
1
iv»
KH29EZ050*
3
* Replaceable cores only
Install field-supplied thermostatic expansion
valve in liquid line ahead of each evaporator
section. For two-step cooling, the solenoids used
must be wired to be opened by control from a
two-step thermostat
For example: two solenoids may be used with
three TXV’s — one of the solenoids serving a liquid
line feeding two of the TXV’s. When three
solenoids are used with three TXV’s, two of the
solenoids must be tied in parallel with the thermo¬
stat to serve the one liquid line feeding the two
TXV’s. The third solenoid operates independently
for the other step of cooling.
Suction Piping at Evaporator and TXV Bulb
Location
The purpose of these recommendations is to
achieve good mixing of the refrigerant leaving the
evaporator suction header for proper sensing by
the TXV bulb.
1. A minimum of two 90° elbows must be
installed upstream of the expansion valve bulb
location.
2. The thermal bulb must be strapped to a vertical
riser following the second elbow of item 1. This
riser must be at least 15 pipe diameters high
and the bulb should be fastened 10 pipe
diameters above the preceding elbow.
3. S i ze the suction line from near evaporator thru
the 15 diameter long riser for high velocity.
Enter the suction pipe sizing charts in Carrier
System Design Manual at corrected design tons
(each evaporator split) and 80 feet equivalent
length (for 2° loss). Choose the smaller size
pipe, when reading falls between two sizes on
chart. Since the selection of suction piping
recommended for high velocity is approxi¬
mately 20 ft equivalent length, this sizing
method will result in about 0.5° friction loss
for that section. If a 2° loss is allowed for the
entire suction line, this leaves 1.5° tor the
balance of suction line and should be sized on
that basis. This high-velocity sizing should be
adequate for oil return up the 15 diameter long
riser. It should be checked.
If an oil return connection at the bottom of the
suction header is supplied with an evaporator, this
connection must be teed in ahead of first mixing
elbow (Fig. 8). When the compressor is below the
evaporator, the riser at the evaporator does not
have to extend as high as the top level. After the
15 diameter riser has been provided, the suction
may elbow down immediately.
Safety Relief — A fusible plug is located on unit
liquid line before liquid valve.
WIRING AND ELECTRICAL DATA
Power Supply — Electrical characteristics of avail¬
able power supply must agree with unit nameplate
rating. Supply voltage must be within tolerances
shown in Table 6. Phase unbalance must not
exceed 2%. Operation of unit on improper supply
voltage or with excessive phase unbalance con¬
stitutes abuse and is not covered by Carrier
Warranty.
Power Wiring — All power wiring must comply
with applicable local and national codes. Install a
field-supplied branch circuit disconnect switch of a
type that can be locked “Off’ or “Open.” Run
power wires from the disconnect switch thru the
power opening (H on Fig. 1) on unit and connect
to terminal block just inside the opening. On
38AB084, there are two terminal blocks (on
208-volt and 230-volt units only). Each is limited
to 350 MCM maximum wire size (see Table 7).
These units are provided with two power openings
to accommodate two conduit runs.
For access to power opening and terminal
blocks on 38AD044, unlatch the two latches on
the outer hinged door and swing open outer door.
Remove screws on barrier panel and remove barrier
to expose wiring.
5

Table 6 — Electrical Data (3-Phase, 60-Hz)
COMPRESSOR
FAN FLA
el
Nameplate
Voltage
Suppl ied*
Voltage
MWA
ICF
400
200
180-229 122
333
500
230 207-264 103
314
600
460 414-528 50 156
100
575 518-660 41 125
410
200 180-229 175 455
510
230
207-264
154
428
610
460
414-528
77 .; 214
110
575
518-660 62 172
400
200
180-229 175 477
500
230
207-264
158
458
600
460 414-528
81
229
100
575
518-660
63
183
400
200
180-229
213
424
500
230
207-264
181
390
600
460 414-528
90 195
100
575 518-660 73
158
410
208
187-229 1 271
547
510
230 198-254 263 508
610
460 414-506 131 253
no
575
518-632 108
204
410
208
187-229
306
624
510
230
198-254
303
577
610
460 414-506 152
288
no 575 518-632 125 232
410
208
187-229
246/206t
842
510 230
198-254
226/190t
780
610
460 414-506 189 390
no
575 518-632 152
312 3
85 8
71.5
37.5
28.6
123 O'”
108 6
54 4
43.6
123 0
1114
57 2
_ 45 - °
No^l_ N o .
~85~8 85
71 5 71
37 5 37
28.6 28
No. 1
"320
300
0
0
FUSE
RA
No. 1
No. 2,3
AMPS
1 320
4 5 '1
4 5 150
1 300 4 5 ; 4.5
125
i50
1 9 1 9 60
1.20 1.6
1.6
50
1 436 6 2 6 6
200
1 410 6.2
6 0
| 175
1 205
3.0 3 0 90
i;64
2.4
2.4
70
I 458
6 2 6 6 200
I 440
6 2
6 0 200
1 220
3.0
3.0 90
176 2.4 2.4
80
1 No. 2
32Cf
6 2 6 6
250
300
6 2 i
6.0
250
f ::: T 5 0
3 0 !
3 0
110
I 120 2.4 d
2.4 100
No. 1,4
6.2
6 2
3 0
2.4
6 2
6 2
3 0
2. 4
6 2
6 2
3 0
2 4
No. 2,3,5,6
6 6
6 0
3 0
2.4
6 6
6 0
3 0
2.4
6 6
6 0
3 0
2 4
Shaded values are LRA drawn by first winding of
-> part-winding start units (not standard on 38AB054,064,
but may be field modified) See Note 1 Larger value is
total LRA.
FLA - Full Load Amps
ICF — Maximum Instantaneous Current Flow (sum of LRA of
last compressor to start and FLA of all other motors in
unit, and control circuit current)
LRA — Locked Rotor Amps
MWA — Minimum Wire Amps per NEC, Section 430-24 Values
based on maximum of 1% voltage drop in line.
*Units are suitable for use on electrical systems where voltage
supplied to the unit terminals is never below or above the listed
limits
tUnits 38AB084 (208 , 230-volt only) have two power connections
Maximum wire size is 350 MCM each
NOTES
1 Dual compressor units have a 4- to 12-second delay between
first- and second-compressor start-up Units are supplied with
either across-the-line or part-winding start, depending on unit
size and voltage Refer to Electrical Data table Where two LRA
values are shown, units are part-winding start, (all others are
across-the-line)
2 Units have factory-installed circuit breakers and/or pullout fuses
that meet NEC requirements for branch circuit over-current
protection and in-sight disconnect Consult local codes
3 Maximum Incremental Current Inrush during start-up is LRA
drawn by first winding of part-winding start unit (shaded area)
or across-thedine LRA of largest compressor when part-winding
start is not available
4 Fans no 1 and 4 have single-phase speed control motors on 208-
and 230-volt units
5 Units 38AB054 and 064 which have two contactors, can be
converted to part-winding start by addition of two time-delay
relays (Carrier part no HN67SK001 for 208- and 230-volt units,
or no HN67SK002 for 460- and 575-volt units) Two additional
contactors are also required with 460- and 575-volt units to be
wired same as other part-wind compressors
On 38AD024 thru 034 units, power terminal
block is in the control box. Remove the outer
panel and remove the no. 10 screw on the door.
Swing open door, remove screws on barrier panel
and remove barrier panel. On 38AB054,064 and
084 units, remove two screws holding hinged sheet
metal barrier and swing open barrier.
Condenser fans must rotate clockwise when
viewed from above. If necessary, correct direction
of fan rotation by interchanging any two power
input wires at disconnect switch.
Affix crankcase heater decal to unit disconnect
switch.
Control Circuit Wiring — Internal control voltage
on 38AD units is 115 volts. Internal control
voltage on 208- and 230-volt 38AB units is the
same as unit voltage. On 460- and 575-volt 38AB
units, it is 115 volts. All control circuit wiring must
comply with applicable local and national codes.
Remote control wiring must enter unit control box
thru control opening (G on Fig. 1) and connect to
terminal block inside the control box.
772 6

Table 7 — Maximum Field Wire Sizes
UNIT
SIZE
VOLTS
(60-Hz)
WIRE SIZE
CONN.
38AD
024,028/034
208
230
6 AWG to 350 MCM
TB
460
575
14 AWG to 2/0
044
460
575
208
230
6 AWG to 350 MCM I
TB
CT
38AB
054,064
208
230
6 AWG to 350 MCM
CT
460
575
6 AWG to 3/0
084
All
6 AWG to 350 MCM
CT
CT - Compression Terminal (attached to terminal block)
TB — Terminal Block (with integral compression terminal)
TB
DT---
0 ---
0 -- -
0 ---
0
0 -
-T
I
-I -
I
_-4
TC|
TC;2*^0-
'i s, fea-
-- L - 2 %X3
TWO STEP COOLING
38AB054, 064 AND 084
_I
LEGEND
CR — Control Relay TC — Thermostat, Cooling
LLS — Liquid Line Solenoid -Field Wiring
TB — Terminal Board (at unit) *Field Supplied
Fig. 10 — Control Circuit Wiring with Line Voltage
(115, 208- or 230-volt) Thermostat
LINE VOLTAGE REMOTE CONTROL - Install
field-supplied line voltage thermostat(s) as shown
in Fig. 10 for two-step cooling. Wire liquid line
solenoid as shown.
LOW-VOLTAGE REMOTE CONTROL - Install
field-supplied accessories as shown in Fig. 11 or
Fig. 12 for either two-step cooling or two-step
cooling, one-step heating. Wire liquid line solenoids
as shown.
START-UP
Preliminary Checks
-> 1. Compressor oil level must be visible at sight
glass in each compressor crankcase. Add oil if
necessary.
2. Each compressor must float freely on its
mounting springs.
3. All internal wiring connections must be tight,
and all barriers and covers must be in place.
-> Toggle switches for units 38AB054,064 and 084
must be in “On” position.
4. Electrical power source must agree with unit
nameplate rating.
5. All service valves must be open.
6. Fan cycling thermostat sensing bulb must be in
air stream under fan no. 1.
7. Crankcase heater must be firmly locked into
the compressor crankcase.
Leak Test the entire refrigerant system by the
Pressure Method described in the Carrier Standard
Service Techniques Manual, Chapter 1, Section 1-6.
Use R-22 at approximately 25 psig backed up with
an inert gas to a total pressure not to exceed 245
psig.
Evacuate and Dehydrate the entire refrigerant
system by either of the methods described in the
Carrier Standard Service Techniques Manual,
Chapter 1, Section 1-7.
Li
38A B , 0 5 4,0 6 4, 084,
SDRl
>-2l
(IMS)
-
SR|
—' p-6
i(0-OH-
l ONE “ STEP
HEATING
CONTROLS
THERMOSTAT HH07AT072
SUBBASE HH93AZ080
LEGEND
AHA — Adjustable Heat
Anticipator
CC — Cooling Compensator
CR — Control Relay
HD — Heating Device
IFR — Indoor Fan Relay
IMS — Indoor Motor Starter
LLS — Liquid Line Solenoid
R — Relay (Accessory)
SDR - Solenoid Dropping Relay
SR — Solenoid Relay
TB — Terminal Board
TC — Thermostat, Cooling
TH — Thermostat, Heating
- Factory Wired
-Field Wired
| | Terminal Board Conn.
at Unit
^Field Supplied
Fig. 11 - Control Circuit Wiring with
24-Volt Accessories (38AB Units Only)
7
772

CONTROL POWER AT 38AD UNIT
CR — Control Relay
HD — Heating Device
IFC — Indoor Fan Contactor
IFR — Indoor Fan Relay
LLS — Liquid Line Solenoid
R — Heating Relay (field-supplied 24-volt sealed coil, 10VA
maximum rating)
SDR — Solenoid Dropping Relay
TB — Terminal Board
TC — Thermostat, Cooling
TH — Thermostat, Heating
-— Factory Wiring
_Field Wiring
^Jumper removed only when separate 24-volt power sources are
available for heating and cooling
fTo control heating device and provide automatic indoor fan
operation on heating
-> Fig. 12 — Control Circuit Wiring with 24-Volt
Accessories (38AD units only)
Preliminary Charge — Refer to Carrier Standard
Service Techniques Manual, Chapter 1, Section 1-8,
for charging methods and procedures mentioned
below.
Charge system with approximately 25 lb of R-22
(75 lb for 38AD044, 38AB054,064 and 084 units)
by the Liquid Charging Method and Charging by
Weight Procedure.
Energize the Branch Circuit, set space thermostat
above ambient. Close field disconnect switch and
turn on unit circuit breakers. Be sure compressor
crankcase heater(s) is operating. Allow crankcase
heater(s) to operate a minimum of 24 hours before
starting unit.
To Start Unit, set space thermostat below ambient,
to ensure circuit operation. On 38AD044 and
38AB084, push control circuit reset button(s).
After starting unit, there will be a delay of about
'15 seconds (12 seconds on 38AD044 and
38AB084) before first compressor starts.
Charging System
1. Block condenser coils to maintain 125 F con¬
densing temp at 280 psig, then add additional
charge to clear sight glass. (If long liquid lines
or vertical lifts greater than 25 ft are used, a
liquid line sight glass should be installed at
condensing unit and used for charging
purposes.)
2. After sight glass has cleared, additional charge
must be added per Table 8, to flood subcooler
circuits in condensers.
After Charging the System, allow unit to run for
about 20 minutes. Stop unit and check compressor
oil level. Add oil only if necessary to bring oil into
view in sight glass. If oil is added, run unit for
additional 10 minutes. Stop unit and check oil
level. If level is again low, add oil only after
determining that piping system is designed for
proper oil return and that the system is not leaking
oil. Check the operation of all safety controls.
Replace all service panels. Be sure that control
panel door is closed tightly.
Table 8 — Charging Data (R-22)
UNIT
REFRIG CHG (lb)
REFRIG
STORAGE
CAP. (lb) f
Sub-cooler
Coil*
38AD024
8
70
38AD028
8
77
38AD034
7
99
3 8 AD 044 15
161
38AB054
12
154
38AB064
10
198
38AB084
21
322
*For maximum system capacity without receiver
f At 120 F condensing temp with condenser 80% full of
liquid
NOTE
Values shown do not include charging requirements for
cooling coils and piping
SERVICE
Capacity Control is by either one or two suction
pressure actuated unloaders. Each controls two
cylinders. Unloaders are factory set (see Table 9)
but may be field adjusted. No. 1 unloader is on
cylinder bank on same side of compressor as
terminal box.
CONTROL SET POINT (cylinder load point) is
adjustable from 0 to 85 psig. To adjust, turn
control set point adjustment nut (Fig. 13) clock¬
wise to its bottom stop. In this position, set point
is 85 psig. Then, turn adjustment counterclockwise
to desired control set point. Every full turn
counterclockwise decreases set point by 7.5 psig.
PRESSURE DIFFERENTIAL (difference between
cylinder load and unload points) is adjustable from
6 to 22 psig. To adjust, turn pressure differential
adjustment screw (Fig. 13) counterclockwise to its
back stop position. In this position, differential is 6
psig. Then, turn adjustment clockwise to desired
pressure differential. Every full turn clockwise
increases differential by 1.5 psig.
772
8

Table 9 — Physical Data
UNIT
38AD024
38AD028
! 38AD034
38AD044 38AB054
f 38AB064
38AB084
OPER WT (lb)
1750
1900
2300 ' 3200 3145 3830
4960
REFRIGERANT
R-22
Oper Chg (lb)*
28 0 |
1 30 5 j
| 35 5 j
; 66 0 1
57 0 |
| 71
0 J
132 0
COMPRESSOR
Reciprocating Hermetic — 1750 rpm
Number
1
1
1
1 2 !
I 2 ]
2
1 2
Model
06ED250 06EE266
06EE275 :
06EA
250
06ED
250
06EA
250
06EE.
275
06EA
275 1
06 EE
275
06EA
, 299
06EE
299
Cylinders
4
4
6
4 4
4
6
6
6
6
6
Oil (pt)
14
14 19
14
14
14
19
19
19
19
19
Crankcase Htr
125 Watts
Protection
Solid State & Ckt Bkr
Thermotector & Ckt Bkr
Solid State
& Ckt Bkr
Cap. Control
Suction Pressure Cylinder (Jnloader(s
)
No. 1
Unloader Settings (ps
ig)
Load
76 78 d
78
88
-
79
-
79
-
79
Unload
58
60 •;!
60 66
-
66
-
66
-
66
No. 2
Unloader Settings (psig)
Load
-
76 76
-
\
76
-
76
-
76
Unload
-
58 58
-
i
„_i
58
-
58
-
58
COND FANS
Axic il Flow;
Direct Drive
Number
3
3 $
3
3
6
i «
S 1
6
Rpm
1140 1140 iiij
1140
1140
1140
1140 1140
Diam (in.)
26 30 30
30
30
30 30
Motor Hp (ea)
%
1
1
1
1
1 1
Cfm
18,200
25,200 28,200 ; i :
' i
■ 31,000
50,400
j 56,400
S 62,000
COND COIL
Plate Fins; 3-rowt
Sections
1
1
1
l > l
2 i
! : 2 1
2
Face (sq ft) 35 4 39 0
49 6
60 4 78 0 |
99 2
120 8
Capacity (l b ) $
70 77
99
161 154
198 322
ELEC CONTROLS
Time Guard Circuit**
Pressurestat Du
al
... . Cutout
High r
Cut-in
375 Psig
275 Psig
. Cutout
Low
Cut-in
29 Psig
29 Psig 29 Psig
44 Psig
45 Psig
63 Psig
Pressurestat
Capacity Control
Cutout
-
_
57 Psig
57 Psig
Cut-in
- -
87 Psig
87 Psig
Pressurestat
Oi
1 Pressure Con fro 1
Cutout
5 Psi Above Suction Pressure
Thermostat
Fan Cycling
No. 1
Opens, 70 F; Closes, 75 F
No. 2
Opens, 57 F; Closes, 62 F
Thermostat
Opens
Discharge Line
, 290 F; Closes, 210 F
PRESS. RELIEF
F u s i b L
e Plug
DISCHARGE LINE
1 ]
1
2
2
2
2
CHECK VALVE
I
* Approximate charge for maximum system capacity Holding charge
factory supplied with all units
f Unit 38AD044 and 38AB084 have 4-row coi)
Time Guard Circuits
BASIC FUNCTIONS OF TIME GUARD CIRCUIT
on all units provide for normal (12 to 15 sec)
momentary delays after the thermostat closes and
before compressors) start. The circuit also pro¬
vides for a longer delay (4 min 45 sec to 5 min
30 sec) in the event of thermostat short cycling or
momentary power failure.
^Storage capacity at 120 F condensing temp with condenser 80%
full of liquid
**Short-cycJe protection
38AD024 THRU 044 UNITS
In addition to the basic functions, timers in
these units provide additional delays for oil
pressure switch bypass (40 sec), winter start
provision (150 sec) bypass of low-pressure switch
and part-winding start (1 sec), if used.
9
772

38AB084 UNIT
Timers in this unit provide basic function, plus
40 sec bypass for oil failure switch and 1 sec delay
to accomplish part-winding start.
For specific sequence for each unit, refer to
Timing Charts in Fig. 14.
PRESSURE
DIFFERENTIAL
ADJUSTMENT
SCREW
BYPASS
PISTON
CONTROL
SET POINT
ADJUSTMENT
NUT
VALVE BODY
DIFFERENTIAL SCREW'
SEALING CAP
(CAP MUST BE REPLACED
TO PREVENT REFRIGERANT LEAKAGE)
Fig. 13 — Capacity Control Valve
o
38AB054 THRU 064 UNITS
H--40SEC '-5
NOTE BLACK INDICATES CLOSED CONTACTS
38AB084 UNITS
Fig. 14 — Timing Charts
Control Circuit Reset
38AD024 THRU 044 AND 38AB084 - Control
circuit locks out on these units in the event of oil
pressure loss, excessive motor temperatures, or
excessive discharge temperatures Reset is
accomplished by pushing reset button(s) in unit
control box.
38AB054 AND 064 - Loss of oil pressure or
excessive motor temperatures cause control circuit
lock out on these units Reset is accomplished by
pushing reset button on oil failure safety
switch(es). All other safety controls on each unit
are automatic reset, with restart accomplished
through unit timers.
Oil Pressure Safety Control (OPS) for each com¬
pressor will stop unit if oil pressure differential is
not established or maintained at either compressor.
If OPS stops unit, determine and correct the
cause (such as loss of compressor oil or flooded
compressor) before restarting unit. Failure to do so
will constitute abuse. Equipment failure due to
abuse is not covered by the Warranty To restart
unit, push manual reset button in unit control box
(except 38AB054 and 064 units). Reset button is
on OPS on 38AB054 and 064.
Compressor Motor Protection on 38AD024 thru
044 and 38AB084 consists of three temperature
sensors (one for each phase) embedded in the
motor windings, and solid state modules in unit
control box.
Sensors are part of a temperature bridge. If a
motor winding overheats, the bridge circuit will
unbalance and a silicone-controlled rectifier in the
module will de-energize a relay which opens a set
of normally open contacts in the module and stops
the compressor.
If one sensor fails, it can be jumped with a
75-ohm, 2-watt resistor. When checking or testing
module, do not apply more than 6 volts across
sensor terminals. Many test instruments exceed this
voltage rating; check before using.
If a component in a module fails on 38AD024
thru 044, the entire module must be replaced. On
38AB084, the transformer is external to the
module and may be replaced separately. Replace
transformer with a Carrier specified balanced
transformer.
To restart compressor after shutdown due to
motor protection trip, push control circuit reset
button in unit control box.
Safety Relief - All 38AB,AD units are protected
against excessive pressure by a fusible plug inserted
in the liquid line.
-> Winter Start Control — On 38AB units (not
necessary on 38AD units because the timer
supplies this function), install a liquid line pressure-
stat (Carrier part no. HK02AB026) and evaporator
freeze-up protector (defrost thermostat. Carrier
part no. HH22UA025).
38AD control circuits incorporate a 150 sec¬
onds timed bypass of the low-pressure switch to
in

allow unit to start under low-ambient conditions.
An evaporator freezestat must also be installed in
series with the control thermostat(s) to prevent
coil freeze-up (See lower part of Fig 15 - EDT
Wiring section.)
LIQUID LINE PRESSURESTAT - Connect to
system liquid line service valve port. Connect
switch into control circuit as shown on unit label
diagram or in Fig. 15. Pressurestat is set to cutout
at 5 psig with a differential of 10 psig. Do not
change setting
Fig. 15 — Unit Wiring Changes for
Winter Start Control
DEFROST THERMOSTAT — Position switch so
that moisture cannot enter switch insulator. Install
control with approximately 2 in. of top of thermo¬
stat capillary passing thru lower part of evaporator
coil and with remainder of capillary inserted
between fins on entering air side of coil. Connect
thermostat electrical contacts into indoor cooling
thermostat circuit or in series with compressor
holding coil.
Thermostat is set to cut out at 25 F and cut in
at 55 F. Contact rating is 16 amps and 230 volts.
As evaporator coil frosts, coil fin temperature
drops to thermostat cutout setting, and stops
compressor. Evaporator fans keep running to
defrost coil with room air. As indoor coil defrosts,
fin temperature will rise to thermostat cut-in
setting. Compressor starts when cooling is required.
NOTE. Use a defrost thermostat on all systems
operating with outdoor temperatures below 45 F.
Fan Adjustment — When replacing a fan, adjust fan
until top surface of hub plate is below the top of
the orifice ring as indicated in Fig. 16. Then,
tighten both setscrews, located over the keyway of
the fan hub of the motor shaft. Seal recessed area
of fan hub bore with Permagum to prevent rusting.
Lubrication
FAN MOTORS have permanently lubricated bear¬
ings. No provisions for lubrication are made.
COMPRESSOR has its own oil supply. Loss of oil
due to a leak in the system should be the only
reason for adding oil after the system has been in
operation.
To Add or Remove Compressor Oil
1. Stop compressor and close suction service valve.
Pump down compressor to 2 psig. Stop com¬
pressor and close discharge shutoff valve.
2. Relieve crankcase pressure by disconnecting
line, at compressor, which goes to low-pressure
connection of oil safety switch.
3. Add oil thru oil filter connection.
4. Remove oil thru drain plug in bottom cover.
Remove small amounts of oil thru oil discharge
connection with compressor running.
Fig. 16 — Fan Adjustment
11

For replacement items use Carrier Specified Parts.
Manufacturer reserves the right to change any product specifications without notice.
CARRIER AIR CONDITIONING COMPANY • SYRACUSE,
Tab 4 Form 38AD-6S) Supersedes 38AD-5SI Printed in U.S.A. 37 3 4-72 Codes Band MS
NEW YORK
Catalog No. 533-860