Carrier | 38AQS012 | Wiring Diagrams

38AQS012,016
Air-Cooled Split System Heat Pump
50/60 Hz
Wiring Diagrams
Units Produced After December 1998
DIAGRAM INDEX
Unit
38AQS
V-Ph-Hz
012,016
208/230-3-60
230-5-50
400-3-50
460-3-60
575-3-60
UNIT LABEL DIAGRAM
Label Diagram
No.
Schematic
Figure
Component Arrangement
Figure
38AK502714
1
2
38AK502724
3
4
38AQS Field Wiring Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig. 1-4
Motormaster® Control Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig. 5-12
LEGEND (Fig. 1 through 12)
AHA
C
CAP
CB
CC
CH
CLO
COMP
CR
CT
CTD
DB
DFB
DFR
DFT
EQUIP
FCPS
FLA
FU
GND
HPS
HR
IFC
IP
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Adjustable Heat Anticipator
Contactor
Capacitor
Circuit Breaker
Cooling Compensator
Crankcase Heater
Compressor Lockout
Compressor
Control Relay
Current Transformer
Compressor Time Delay
Defrost Board
Defrost Board
Defrost Relay
Defrost Thermostat
Equipment
Fan Cycling Pressurestat
Full Load Amps
Fuse
Ground
High-Pressure Switch
Heater Relay
Indoor-Fan Contactor
Internal Protector
L
LCS
LLS
LOR
NDR
NEC
OFC
OFM
OFR
OPS
PCB
QT
R
RC
RH
RVR
RVS
SOL
TB
TC
TH
TRAN
U
UR
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Light
Loss-of-Charge Switch
Liquid Line Solenoid
Lockout Relay
No-Dump Relay
National Electrical Code
Outdoor-Fan Contactor
Outdoor-Fan Motor
Outdoor-Fan Relay
Oil Pressure Switch
Printed Circuit Board
Quadruple Terminal
Isolation Relay
Cooling Connection (Thermostat)
Heating Connection (Thermostat)
Reversing Valve Relay
Reversing Valve Solenoid
Solenoid
Terminal Block Terminal
Thermostat — Cooling
Thermostat — Heating
Transformer
Unloader
Unloader Relay
Terminal (PCB, Field)
Terminal (Marked)
Terminal (Unmarked)
Terminal Block
Splice (Factory)
Splice (Field)
Splice (Marked Wire)
Wiring Factory
Wiring Field Control
Wiring Field Power
Option or Accessory
PCB Run
NOTES
1. Compressor and fan motor(s) thermally protected. Three-phase
motors are protected against primary single-phasing conditions.
2. If any of the original wire furnished must be replaced, it must be
replaced with type 90 C wire or its equivalent.
3. Terminal block 2 (TB2) is for field external control connections,
Class 2 wiring. Supply voltage at TB2 is 24 vac. Maximum
power available at TB2 is 31.5 va.
4. Field-supplied component ratings: IFC sealed coil rating
(24 vac) 12 va max.
5. Use thermostat HH07AT172 with subbase HH93AZ177.
6. Use copper, copper-clad aluminum, or aluminum conductors for
field power supply only.
7. Insulate unused lead when changing tap for 208 volt use.
8. The CB must-trip amps are equal to or less than 140% FLA.
9. Set thermostat heat anticipator(s) for first stage .79; for second
stage .63.
10. The CLO locks out the compressor to prevent short cycling on
compressor overload and safety devices. Before replacing CLO,
check these devices.
11. Remove jumper between RC and RH.
12. Defrost cycle time is factory set at 30 min.
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
PC 111
Catalog No. 533-80074
Printed in U.S.A.
Form 38AQS-2W
Pg 1
11-02
Replaces: 38AQS-1W
Book 1 4
Tab 5a 5a
SEQUENCE OF OPERATION —
38AQS012,016 OUTDOOR UNIT
SECOND STAGE — If additional heating is required, TH2
on the thermostat closes, causing the auxiliary heat supply (i.e.,
electric resistance heat) to be energized in 1 or 2 stages depending on the number of stages available and whether the outdoor
thermostats are closed.
Assume the power is on and the thermostat is set at SYSTEM AUTO, FAN AUTO. and desired temperature.
Cooling — If power to unit has been off for an extended
period of time, energize crankcase heater at least 24 hours prior
to starting compressor.
The indoor fans, outdoor fans, and compressor start within
5 minutes (due to compressor time delay) on command from
the controlling thermostat in either the Cooling or the Heating
mode of operation. When first stage cooling is required, thermostat (TC1) closes, causing the heat pump to start with an
unloaded compressor. When TC2 closes, demanding additional
cooling, the compressor loads. In a system with a one-stage
thermostat, the unit may be wired so the compressor starts fully
loaded. The RVS (reversing valve solenoid) is deenergized
during Cooling mode operation.
Defrost Cycle — Defrost is initiated by a timer which
may be set to 30, 50, or 90 minutes. The cycle begins when the
defrost timer motor contacts close for 20 seconds. If the defrost
thermostat is closed, the reversing valve and outdoor-air fans
are deenergized. The unit operates on this modified Cooling
mode to defrost the coil. The defrost cycle continues until the
defrost thermostat or defrost high pressure switch opens or
10 minutes have elapsed.
When the unit is in the defrost cycle, electric resistance heat
is energized to prevent cold air recirculation during this modified Cooling mode.
Air Circulation — When the fan switch is at FAN ON,
the indoor-air fans operate continuously to provide ventilation.
The thermostat operates the other components as described
above.
Heating
FIRST STAGE — When the thermostat (TH1) calls for heating, the indoor-fan motor, outdoor-fan motors, and the compressor (fully loaded) are energized. The RVS is energized in
the Heating mode.
2
Fig. 1 — Schematic — 38AQS012,016; 208-230/3/60, 230/3/50 and 400/3/50 Units
3
Fig. 2 — Component Arrangement — 38AQS012,016; 208-230/3/60, 230/3/50 and 400/3/50 Units
4
Fig. 3 — Schematic — 38AQS012,016; 460/3/60 and 575/3/60 Units
5
Fig. 4 — Component Arrangement — 38AQS012,016; 460/3/60 and 575/3/60 Units
6
MOTORMASTER® CONTROL
(LOW AMBIENT KIT)
INSTALLATION
VERIFY POWER WIRING — Power wiring must comply
with NEC (National Electrical Code) and all requirements.
Confirm that supply voltage meets minimum voltage specified
on the unit’s rating plate and that it matches the voltage rating
of the low-ambient kit.
The accessory low-ambient kit contains a fan speed (Motormaster) control device activated by a temperature sensor
(Fig. 5). The kit controls condenser fan motor speed in
response to the saturated condensing temperature. For outdoor
temperatures down to –20 F (–29 C), it maintains the condensing temperature at 100 ± 10 F (38 ± 6 C).
The low-ambient (Motormaster) control consists of a solidstate circuit on a printed circuit board encased in an aluminum
extrusion. The control must be fastened to a panel in the unit,
and the sensor assembly (Fig. 5) mounted to a return bend on
the unit’s condenser coil. Parts necessary for mounting control
and sensor are included in the kit.
LOW-AMBIENT
CONTROL
SENSOR
ASSEMBLY
C
A
B
Pre-Installation
DISCONNECT UNIT POWER — To prevent electric shock,
open and tag all disconnects before modifying the condensing
unit.
FABRICATE AND INSTALL WIND BAFFLES — The
38AQS units equipped with the low-ambient kit require baffles to prevent wind crosscurrents from causing abnormal
operation as the fan is modulated. Construct and install
wind baffles. See Fig. 6.
KIT NO.
32LT900301
VOLTS
All except 460
AMPS
8.0
A
57/8
B
63/16
C
33/8
32LT900611
460
4.0
57/8
73/8
33/8
Fig. 5 — Low-Ambient (Motormaster) Control and
Sensor Assembly
7
DIMENSIONS (ft-in.)
BAFFLE LOCATION
Right-Hand Side*
Back
Left-Hand Side*
A
2-511/16 (754.3 mm)
5-81/8
(1730.3 mm)
(925.6 mm)
3-07/16
*As viewed from access panel side.
Fig. 6 — Wind Baffle Details
8
Installation — After completing the pre-installation steps,
proceed as follows:
MOUNT CONTROL ASSEMBLY
1. See Fig. 7 for the location of the access panel and
Motormaster® low-ambient control in the bottom of the
unit. Remove the access panel.
2. Using the template supplied in this document, drill pilot
holes for mounting the low-ambient control.
2. Coil and secure excess wire inside the unit near the sensor
or next to the low ambient control; provide additional
protection against abrasion or movement of the wire if
necessary.
3. Reinstall the access panel.
When drilling holes, be careful not to damage return coil
bends inside unit.
3. Fasten control to unit with four no. 10 sheet metal screws
and star lockwashers provided. Lockwashers are required
to ensure electrical ground with condensing unit.
MOUNT SENSOR ASSEMBLY
The sensor assembly is fragile. Handle with care.
1. See Fig. 8 to determine where to locate sensor on coil
return bend. As shown in Fig. 9, fasten sensor to return
bend with the supplied screw, plate washers, and nut. See
Table 1 for sensor temperature vs resistance values.
Table 1 — Sensor (Thermistor) Temperature
vs Resistance
TEMPERATURE
F
C
60
16
70
21
77
25
80
27
90
32
100
38
110
43
120
49
NOMINAL RESISTANCE
(Ohms)
7750
5900
5000
4650
3650
2875
2275
1850
Fig. 8 — Motormaster® Sensor Location —
38AQS012,016
Fig. 7 — Motormaster Control Location
9
Fig. 9 — Sensor Installation
INSTALL CONTROL POWER WIRING — Wire the Motormaster® low-ambient control to the unit’s power circuit as
shown in Fig. 10 and 11; refer to the following sections for
various unit voltages.
Install the isolation relay coil in parallel with the reversing
valve relay coil. This takes the Motormaster control out of the
condenser fan motor circuit when the 38AQS switches to the
heating cycle. (See Fig. 12.)
If fan motor no. 1 does not start, verify the following conditions and correct as necessary:
• Condensing unit power is on.
• Power is present at fan motor relay contacts (or transformer output when one is installed).
• Sensor wire connections inside the low-ambient control
are tight.
If the preceding conditions are met and fan motor no. 1 still
does not start, perform corrective procedures or replace components as follows:
• Jumper the power wires (BLK-to-BLK) in the Motormaster control. If the motor does not run, check motor
wiring and run capacitor. Replace capacitor and motor if
necessary. If the motor runs, ensure the fan motor is
wired in series with the control. Refer to Fig. 10.
• If the fan motor runs when connected to the single-phase
voltage supply but does not run when connected in
series with the Motormaster control, AND the return
bend where the sensor is mounted is warm, short the
sensor leads (BLU-to-RED). If the motor runs, replace
the sensor. If the motor does not run, replace the control
and sensor assembly.
IMPORTANT: Wire low-ambient control in series with
fan motor.
Power wiring must comply with all local and national
requirements. All units except 460-v, 3-ph, 60-Hz use Motormaster control, Carrier Part No. 32LT900301. The 460-v units
use Motormaster control, Carrier Part No. 32LT900611.
ALL UNITS EXCEPT 575-3-60 — For these units, without
special transformer, wire Motormaster control to condenser fan
motor circuit as shown in Fig. 10.
575-3-60 UNITS — The 575-v units require a special fieldinstalled transformer and fan motor. Wire special transformer
(part no. HT01AH859) and Motormaster control to special fan
motor (part no. HC44VL852) as shown in Fig. 11.
Blue wire from CB1-13 to CAP1 must be reconnected from
CB1-13 to TRAN2-H2.
Blue wire from CAP1 to TRAN2-H2 must be reconnected
from CAP1 to field-installed transformer.
VERIFY OPERATION — Turn on the unit power and set the
thermostat below the ambient room temperature. If the unit
is equipped with a Time Guard® II circuit, wait at least
5 minutes.
After the compressor starts, the fan speed is modulated
according to the condensing temperature and then maintained
until the set point is achieved.
W1 W2
*Use control part no. 32LT900301 for all unit voltages except 460 v.
Use control part no. 32LT900611 for 460-v units.
Fig. 10 — Motormaster Control Power Wiring
for All Units except 575-V
Fig. 11 — Motormaster Control Power Wiring
for 575-V Units Using 208/230-V Motors
ORN
ORN
ORN
ORN
HR
1
3
RVR1
ORN
ORN
1 RVR2 3
WHT
WHT
WHT
C TRAN2
3 CR3
3 RVR2
WHT
3
WHT
WHT
3 HR
C TB2
RVR3
ORN
1 RVR3 3
NOTE: Isolation Relay (R) (field supplied) HN61KQ120 or
equivalent.
WHT
RVR1
R
Fig. 12 — Motormaster Control Circuit Wiring with Isolation Relay
Copyright 2002 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. 533-80074
Printed in U.S.A.
Form 38AQS-2W
Pg 10
11-02
Replaces: 38AQS-1W
Book 1 4
Tab 5a 5a
MOTORMASTER® CONTROL TEMPLATE
11
Book
Tab
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
1 4
PC 111
Catalog No. 533-80074
Printed in U.S.A.
Form 38AQS-2W
Pg 12
11-02
Replaces: 38AQS-1W
5a 5a
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CUT ALONG DOTTED LINE
Copyright 2002 Carrier Corporation
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