38AH044-084
Air-Cooled Condensing Units
50/60 Hz
Wiring Diagrams
UNITS PRODUCED AFTER APRIL 1994
(Includes Motormaster® III Head Pressure Control Information)
INDEX
UNIT 38AH
Dual Circuit Units
044-084
ELECTRICAL
CHARACTERISTICS
(V-Ph-Hz)
044-084
044-084
All
208/230-3-60
346-3-50
230-3-50*
460-3-60
575-3-60
380-3-60
380/415-3-50
208/230-3-60
346-3-50
460-3-60
575-3-60
380-3-60
380/415-3-50
All
All
044-084
All
044-084
All
044,064
074,084
Optional Single-Circuit Units†
044-084
All
208/230-3-60
346-3-50
230-3-50*
044,064
460-3-60
575-3-60
380-3-60
380/415-3-50
208/230-3-60
346-3-50
460-3-60
074,084
575-3-60
380-3-60
380/415-3-50
044-084
All
044-084
All
044-084
All
LABEL DIAGRAM
No. 38AK
FIG.
NO.
Component Arrangement
500637
2
Power Label
500629
3
Power Label
500630
4
Power Label
500631
5
Power Label
500632
6
Control Label
VAV Control Label with ModuPanel™ Control
Control Circuit Wiring with 24-V* Accessory Relay and One
2-Stage CCTM
Control Circuit Wiring with Two 24-V Accessory Relays and
Two 2-Stage CCTM
501105
501106
7
8
—
9
—
10
Component Arrangement
500876
11
Power Label
500868
12
Power Label
500869
13
Power Label
500870
14
Power Label
500871
15
Control Label
VAV Control Label with ModuPanel Control
Control Circuit Wiring with 24-V Accessory Relay and One
2-Stage CCTM
501107
501108
16
17
—
18
TYPE
Timer Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Motormaster® III Control Sensor Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Motormaster III Control Signal Selection Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Motormaster III Control Fan Power Wiring — Units 38AH044-064 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Motormaster III Control Fan Power Wiring — Units 38AH074,084. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Motormaster III Control 575-V Units, Autotransformer Circuit — Units 38AH044-064 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Motormaster III Control 575-V Units, Autotransformer Circuit — Units 38AH074,084 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fig. 1
Fig. 19
Fig. 20
Fig. 21
Fig. 22
Fig. 23A
Fig. 23B
LEGEND
CCTM — Carrier Communications Temperature Monitor
*Unit 38AH044 part wind only.
†Optional single-circuit models will display suffix codes DA, EA, FA, or GA.
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
PC 111
Catalog No. 563-879
Printed in U.S.A.
Form 38AH-6W
Pg 1
4-00
Replaces: New
Book 1
Tab 3a
OPERATING SEQUENCE
units). Circuit A (compressor A1 for single-circuit units) is
now operational.
A set of bypass contacts in timer TM-A allows the circuit A
compressor (compressor A1 for single-circuit units) 120 seconds to build sufficient oil pressure. If the oil pressure is insufficient after 120 seconds, circuit A (compressor A1 for singlecircuit units) shuts down and must be reset manually.
A second set of bypass contacts in timer TM-A (TM for
single-circuit units) allows the refrigerant circuit 21/2 minutes
to build sufficient low-side pressure. This time delay is a startup feature for low ambient conditions; no accessory is required.
If refrigerant circuit pressure is insufficient to close the lowpressure switch after 21/2 minutes, the circuit A compressor
(compressor A1 for single-circuit units) shuts down for 5 minutes and then automatically attempts to restart. No manual reset
is required.
FOR DUAL-CIRCUIT UNITS — If circuit A is insufficient
for the cooling requirements, second-stage thermostat TC2
closes to bring circuit B on line. Circuit B follows the same
sequence of operation as circuit A, except a relay delays circuit
B compressor start-up for 40 seconds after a call for cooling.
Because circuit A has a 12-second delay after TC1 closes, and
circuit B has a 40-second delay after TC2 closes, the two compressors cannot start at the same time.
FOR OPTIONAL SINGLE-CIRCUIT UNITS — If compressor A1 is insufficient for the cooling requirements, secondstage thermostat TC2 closes, which opens liquid line solenoid
valve LLS-A2. Compressor A2 starts only after the D-D2
contacts in timer TM close (approximately 21/2 minutes after
compressor A1 is energized) and the suction pressure is sufficient to close capacity control pressure switches CCPS1 and
CCPS2.
NOTE: Liquid line solenoid valves must be field-supplied and
installed at the evaporator for both dual- and optional singlecircuit units.
INDOOR-FAN OPERATION — When the fan switch on the
thermostat is set for automatic operation (AUTO), the fieldsupplied indoor-fan contactor (IFC) is cycled with the lead
compressor. If the fan switch is set at the continuous position
(CONT), the IFC is energized as long as the unit power is on.
Timer Functions — (See Timer Cycle, Fig. 1.) Each
compressor is operated by an independent timer motor which
allows for the independent operation of each refrigeration
circuit.
NOTE: Optional single-circuit units have one timer motor
which controls the lead compressor. Lag compressor is controlled by CCPS (Capacity Control Pressure Switch).
SWITCH A — The timer motor is energized through contacts
A-A1 or A-A2. This establishes the Time Guard® function
which prevents compressor short-cycling. Start of compressor
is delayed approximately 5.5 minutes after shutdown. Compressor B1 start-up is delayed 60 seconds after the T2 call-forcooling by a time-delay relay. This prevents both compressors
from starting at the same time.
SWITCH B — The compressor is initially energized through
contacts B-B1.
SWITCH D — Contacts D-D1 provide a 2.5-minute bypass of
the low-pressure switch at start-up for winter-start control. On
single-circuit units, contacts D-D2 control start-up of compressor A2.
SWITCH E — Contacts E-E1 provide a 120-second bypass of
the oil pressure switch at start-up. If oil pressure does not build
to the required minimum pressure in 120 seconds, the compressor shuts down and the control circuit locks out.
Control Circuit Reset — The control circuit locks out
if the unit shuts down because of low oil pressure or excessive
high-side pressure. To reset the control circuit, open and close
the fan circuit breaker (FCB). This will reset the timer motor,
and the unit will restart under Time Guard® control. If LPS is
not closed, timer will not function. LPS must be closed at time
of start-up. At start-up, if the low-pressure switch (LPS) is not
made after 2.5 minutes, the unit shuts down. When the pressure
is sufficient for the LPS to cut in, the control circuit is energized automatically and start-up proceeds under Time Guard
control.
Unit Operation — Circuits A1 and B1 are controlled by
independent circuitry. It is therefore possible to maintain partial
cooling capability even if one compressor is inoperable.
NOTE: Single-circuit units do not have independent control
circuitry.
On a call for cooling, the first-stage cooling thermostat TC1
closes, energizing the first stage of the condenser fans and timer motor TM-A (TM for single-circuit units). After 12 seconds,
the timer energizes lead compressor contactor C-A1 and the
lead compressor starts. (Circuit A compressor is the lead on
dual-circuit units, and compressor A1 is the lead on singlecircuit units.) At the same time, solenoid drop relay SDR2 energizes and closes its contacts, which energizes and opens liquid line solenoid valve LLS-A (LLS-A1 for single-circuit
Restart After Stoppage by Safety Control —
The high-pressure switch and the oil pressure switch must be
reset manually by breaking the control power supply at any of
the following points: control circuit fuse, fan motor circuit
breaker, or the thermostat. Restart follows the Time Guard®
control delay.
Stoppage by low-pressure switch results in Time Guard
control delay, then unit attempts normal restart.
The compressor motor overcurrent protectors are manualreset circuit breakers. Reset of control circuit may also be
necessary.
2
Head Pressure Control
Dual-circuit units: Fan cycling pressure switches (one on each
circuit) close at 264 ± 7 psig (1820 ± 48 kPag) and open at
160 ± 7 psig (869 ± 48 kPag). The fan cycling pressure
switches control fans no. 3, 4, 5, and 6 on sizes 074-084.
Optional single-circuit units: Fan cycling pressure switch
closes at 264 ± 7 psig (1829 ± 48 kPag) and opens at 160 ±
7 psig (869 ± 48 kPag). The fan cycling pressure switch controls fans no. 3 and 4 on all sizes. Sizes 074 and 084 also
include a fan cycling temperature switch to control fans no. 5
and 6. The temperature switch is closed when the ambient temperature is above 70 F (21 C).
Independent Refrigerant Circuit Controls —
Circuits A1 and B1 are controlled by independent circuitry. It is
therefore possible to maintain partial cooling capability even if
one compressor or unit module is inoperable.
NOTE: Single circuit units do not have independent control
circuitry.
NOTE: Black denotes closed contacts.
Fig. 1 — Timer Cycle
3
LEGEND (Fig. 2-15)
ATS
C
CB
CCPS
CH
COMP
CR
DU
EQUIP
FC
FCB
FCPS
FIOP
FM
FU
GND
HPS
IFC
LLS
LPR
LPS
MMSN
NEC
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
NFPA
OPR
OPS
PL
PR
—
—
—
—
—
Air Temperature Switch
Compressor Contactor
Compressor Circuit Breaker
Capacity Control Pressure Switch
Crankcase Heater
Compressor
Control Relay
Dummy Terminal
Equipment
Fan Contactor
Fan Circuit Breaker
Fan Cycling Pressure Switch
Factory-Installed Option
Fan Motor
Fuse
Ground
High-Pressure Switch
Indoor-Fan Contactor
Liquid Line Solenoid
Low-Pressure Relay
Low-Pressure Switch
Motormaster® Sensor
National Electrical Code
(U.S.A. Standard, NFPA 70)
National Fire Protection Association
Oil Pressure Relay
Oil Pressure Switch
Plug Assembly
Power Relay
PRI
PW
SDR
SEC
TB
TC
TDR
TM
TR
TRAN
U
VAV
XL
—
—
—
—
—
—
—
—
—
—
—
—
—
Primary
Part-Wind Start
Solenoid Drop Relay
Secondary
Terminal Block
Thermostat, Cooling
Time-Delay Relay
Timer Motor
Timer Relay
Transformer
Unloader
Variable Air Volume
Across-the-Line Start
Terminal Block Connection
Marked Terminal
Unmarked Terminal
Unmarked Splice
Marked Wire
Factory Wiring
Field Wiring
Indicates Common Potential;
Does Not Represent Wiring
NOTES (Fig. 2-8 and 11-17)
1. 208/230V units are factory wired for 230-v power supply. For 208-v power
supply, connect yellow wire to terminal marked H2. For 460-v power supply, connect yellow wire to terminal marked H4. For 575-v power supply,
connect yellow wire to terminal marked H2.
2. For units with 115-v controls, connect black wire to the white lead of
TRAN2. For units with 230-v controls, connect black wire to the red lead
of TRAN2. For units with 200-v controls, connect black wire to the blue
lead of TRAN2.
3. Terminal blocks TB3, TBX1, and TBX2 are for external field control connections. Control connections are to be class 1 wiring.
4. Field-supplied components (IFC, LLS-A1 and LLS-A2) must have a maximum sealed coil rating of 30 va each (0.25 amp at 120 vac, 0.13 amp at
230 vac). Thermostats must have a minimum pilot duty rating of 120 va
(1 amp at 120 vac). The fan switch must have a minimum pilot duty rating
of 30 va (0.25 amp at 120 vac, 0.13 amp at 230 vac). On VAV units, the
AHMS IFC_AUX and control staging contacts must have a minimum pilot
duty rating of 120 VA (1 amp at 120 vac).
5. Wiring for field power supply must be rated 75 C minimum. Use copper,
copper-clad aluminum, or aluminum conductors. Maximum incoming wire
size for each terminal block is 500 kcmil.
6. Replacement of factory wires must be with type 105 C wire or its
equivalent.
7. Factory wiring is in accordance with National Electrical Code (NEC). Field
modifications or additions must be in compliance with all applicable
codes.
8. Compressors and fan motors are thermally protected. Three phase
motors are protected against primary single phasing conditions.
9. Line numbers on the left side of the label diagrams indicate the contact
number. The numbers on the right side of the label diagrams match the
contacts with their corresponding coils. A plain number indicates normally
open contacts. An underlined number indicates normally closed contacts.
10. Control circuit power available for field-installed accessories.
4
5
Fig. 2 — Dual-Circuit Units, Component Arrangement, All Voltages
6
Fig. 3 — Dual-Circuit Units, Power Label Diagram — Units 38AH044-064; 208/230-3-60, 346-3-50, 230-3-50
7
Fig. 4 — Dual-Circuit Units, Power Label Diagram — Units 38AH044-064; 460-3-60, 575-3-50, 380-3-60, 380/415-3-50
8
Fig. 5 — Dual-Circuit Units, Power Label Diagram — Units 38AH074,084; 208/230-3-60, 346-3-50
9
Fig. 6 — Dual-Circuit Units, Power Label Diagram — Units 38AH074,084; 460-3-60, 575-3-60, 380-3-60, 380/415-3-50
10
Continued on next page
Continued on next page
11
Fig. 7 — Dual-Circuit Units Control Label Diagram, All Voltages
12
Continued on next page
Continued on next page
13
Fig. 8 — Dual-Circuit Units, Variable Air Volume Label Diagram with Typical Modupanel™ Control Wiring, All Voltages
Continued on next page
LEGEND
C
CR
H
HD
IFC
IFR
LLS
SDR
TB
TR
— Compressor Contactor
— Control Relay
— Heating Relay (field-supplied
24-v sealed coil,
10 va maximum rating)
— Heating Device
— Indoor-Fan Contactor
— Indoor-Fan Relay
—
—
—
—
Liquid Line Solenoid
Solenoid Drop Relay
Terminal Block
Timer Relay
Factory Wiring
Field Wiring
*Jumper removed only when separate 24-v transformer power source is used to power the TSR-01 relay pack.
†To control heating device and provide automatic indoor-fan operation on heating.
NOTES:
1. Liquid line solenoid valve LLS-A is used for solenoid drop on circuit A. Liquid line solenoid valve LLS-B is used for
solenoid drop for circuit B.
2. Solenoid drop is a safety feature which prevents refrigerant migration to the compressor during the OFF cycle. It
is recommended on all systems and required on systems where piping exceeds 75 ft in length.
3. TSR-01 relay pack uses 10 va. Internal relay contacts are rated for 1 amp/24 vac.
Fig. 9 — Control Circuit Wiring with 24-V Accessory Relay and
One 2-Stage Carrier Communications Temperature Monitor, All Voltages (Dual-Circuit Units)
14
Fig. 9 — Control Circuit Wiring with 24-V Accessory Relay and
One 2-Stage Carrier Communications Temperature Monitor, All Voltages (Dual-Circuit Units) (cont)
15
Continued on next page
LEGEND
C
CR
H
HD
IFC
IFR
LLS
SDR
TB
TR
— Compressor Contactor
— Control Relay
— Heating Relay (field-supplied
24-v sealed coil,
10 va maximum rating)
— Heating Device
— Indoor-Fan Contactor
— Indoor-Fan Relay
—
—
—
—
Liquid Line Solenoid
Solenoid Drop Relay
Terminal Block
Timer Relay
Factory Wiring
Field Wiring
*Jumper removed only when separate 24-v transformer power source is used to power the TSR-01 relay pack.
†To control heating device and provide automatic indoor-fan operation on heating.
NOTES:
1. Liquid line solenoid valve LLS-1 is used for solenoid drop on circuit A. Liquid line solenoid valve LLS-3 is used for
solenoid drop for circuit B.
2. Solenoid drop is a safety feature which prevents refrigerant migration to the compressor during the OFF cycle. It
is recommended on all systems and required on systems where piping exceeds 75 ft in length.
3. Liquid line solenoid valve LLS-2 is used for capacity control on circuit A system; LLS-4 is used for capacity control on circuit B system.
4. TSR-01 relay pack uses 10 va. Internal relay contacts are rated for 1 amp/24 vac.
Fig. 10 — Control Circuit Wiring with 24-V Accessory Relays and
Two-Stage Carrier Communications Temperature Monitors, All Voltages (Dual-Circuit Units)
16
Fig. 10 — Control Circuit Wiring with 24-V Accessory Relays and
Two-Stage Carrier Communications Temperature Monitors, All Voltages (Dual-Circuit Units) (cont)
17
18
Fig. 11 — Optional Single-Circuit Units, Component Arrangement, All Voltages
19
Fig. 12 — Optional Single-Circuit Units Power Label Diagram — Units 38AH044-064; 208/230-3-60, 346-3-50, 230-3-50
20
Fig. 13 — Optional Single-Circuit Units Power Label Diagram — Units 38AH044-064; 460-3-60, 575-3-60, 380-3-60, 380/415-3-50
21
Fig. 14 — Optional Single-Circuit Units Power Label Diagram — Units 38AH074,084; 208/230-3-60, 346-3-50
22
Continued on next page
23
Fig. 15 — Optional Single-Circuit Units Power Label Diagram — Units 38AH074, 084; 460-3-60, 575-3-60, 380-3-60, 380/415-3-50
24
Continued on next page
25
Fig. 16 — Optional Single-Circuit Units Control Label Diagram, All Voltages
26
Continued on next page
Continued on next page
27
Fig. 17 — Optional Single-Circuit Units, Variable Air Volume Control Label Diagram,with Typical Modupanel™ Control Wiring, All Voltages
Continued on next page
LEGEND
C
CR
H
HD
IFC
IFR
LLS
SDR
TB
TR
— Compressor Contactor
— Control Relay
— Heating Relay (field-supplied
24-v sealed coil,
10 va maximum rating)
— Heating Device
— Indoor-Fan Contactor
— Indoor-Fan Relay
—
—
—
—
Liquid Line Solenoid
Solenoid Drop Relay
Terminal Block
Timer Relay
Factory Wiring
Field Wiring
*Jumper removed only when separate 24-v transformer power source is used to power the TSR-01 relay pack.
†To control heating device and provide automatic indoor-fan operation on heating.
NOTES:
1. Liquid line solenoid valve LLS-1 is used for solenoid drop.
2. Solenoid drop is a safety feature which prevents refrigerant migration to the compressor during the OFF cycle. It
is recommended on all systems and required on systems where piping exceeds 75 ft in length.
3. Liquid line solenoid valve LLS-2 is used for capacity control.
4. TSR-01 relay pack uses 10 va. Internal relay contacts are rated for 1 amp/24 vac.
Fig. 18 — Control Circuit Wiring with 24-V Accessory and One 2-Stage
Carrier Communications Temperature Monitor, All Voltages (Single-Circuit Units)
28
Fig. 18 — Control Circuit Wiring with 24-V Accessory and One 2-Stage
Carrier Communications Temperature Monitor, All Voltages (Single-Circuit Units) (cont)
29
MOTORMASTER® III CONTROL
INSTALLATION
STEP 3 — MAKE ELECTRICAL CONNECTIONS
Before installing Motormaster III control, refer to general
information in Installation Instructions shipped with the control. Comply with the following instructions when applying
Motormaster III control to 38AH044-084 units. Refer to
Table 1 for usage and unit modification data.
To avoid possibility of electrical shock and personal injury,
turn off all power to unit before making electrical connections. Tag all disconnects to alert others not to turn power
on until work is completed.
Table 1 — Minimum Operating Temperatures
UNIT
38AH
044,054
064-084
All the necessary wires required for wiring the Motormaster III controller into the unit wire in the wire harness for
the unit.
38AH044-064 Units — Connect the power wires to the controller from the appropriate fan contactor, FC-A1 or FC-B1.
Remove the red, brown, and orange wires from the fan motor
contactor. Connect the red fan motor wire to the red wire of the
controller. Connect the brown fan motor wire to the brown
wire of the controller. Connect the orange fan motor wire to the
orange wire of the controller. See Fig. 21.
38AH074,084 Units — Connect the power wires to the controller from the appropriate fan contactor, FC-A1 or FC-B1.
Remove the red, brown, and orange wires from the fan motor
contactor. Connect the red fan motor wire to the red wire of the
controller. Connect the brown fan motor wire to brown wire of
the controller. Connect the orange fan motor wire to the orange
wire of the controller. See Fig. 22.
NOTE: For 38AH units, if primary voltage is 575 v, two transformers (part no. HT01AH851) must be used to lower the
supply voltage to the Motormaster III controller to 460 v. See
Fig. 23A or B.
All Sizes — When all electrical connections are made, check
that they are correct and tight. Restore power to unit. Check the
phase sequence indicator on the Motormaster III control. If
lighted, turn off power and reverse L1 (black) and L2 (yellow)
power leads. Check that fan motors rotate in the proper direction. To change fan rotation, reverse the red and orange output
leads to the motor. Replace and secure the control box inner
panel. Close and secure the control box door.
TEMPERATURE
Without Motormaster III
With Motormaster III
Control
Control
F
C
F
C
50
10
–20
–29
35
7.1
–20
–29
Required Changes
STEP 1 — WIND BAFFLES AND BRACKETS — Wind
baffles and brackets must be field fabricated for 38AH units to
ensure proper operation at low-ambient temperatures with
Motormaster III controls.
STEP 2 — INSTALL MOTORMASTER III CONTROLS — Two Motormaster III controls must be added
for each unit, one control per refrigerant circuit. See Motormaster III Installation Instructions for proper control mounting
locations.
Sensors — Install sensor for thermistor input control in proper
location on condenser coil. See Fig. 19 and Motormaster III
Installation Instructions. Connect sensor leads to the purple
and gray control signal leads on the Motormaster III control
located on the same side of the unit.
Control Signal Selection Switch — Remove the cover of the
Motormaster III controller. Set switch on Motormaster III control board (underneath cover) to accept the thermistor sensor
input signal. Also, set the frequency selection switch to match
to unit power supply (50 Hz or 60 Hz). See Fig. 20 for switch
locations and proper position. Replace the cover.
30
Fig. 19 — Motormaster® III Control Sensor Locations
LEGEND
GND — Ground
*For thermistor (sensor) signal, move switch to the left.
NOTE: Thermistor is designated in text as “sensor.”
Fig. 20 — Motormaster III Control Signal Selection Switch
31
FC
FCB
FM
MMSN
LEGEND
— Fan Contactor
— Fan Circuit Breaker
— Fan Motor
— Motormaster Sensor
Fig. 21 — Motormaster® III Control Fan Power Wiring — Units 38AH044-064
32
FC
FCB
FM
MMSN
LEGEND
— Fan Contactor
— Fan Circuit Breaker
— Fan Motor
— Motormaster Sensor
Fig. 22 — Motormaster® III Control Fan Power Wiring — Units 38AH074, 084
33
FC
FCB
FM
MMSN
TRAN
LEGEND
— Fan Contactor
— Fan Circuit Breaker
— Fan Motor
— Motormaster Sensor
— Transformer
Fig. 23A — Motormaster® III Control 575-v Units, Autotransformer Circuit — Units 38AH044-064
34
FC
FCB
FM
MMSN
TRAN
LEGEND
— Fan Contactor
— Fan Circuit Breaker
— Fan Motor
— Motormaster Sensor
— Transformer
Fig. 23B — Motormaster® III Control 575-v Units, Autotransformer Circuit — Units 38AH074, 084
35
Copyright 2000 Carrier Corporation
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
PC 111
Catalog No. 563-879
Printed in U.S.A.
Form 38AH-6W
Pg 36
4-00
Replaces: New
Book 1
Tab 3a