Carrier 38AUZ Dimensions and installation guide

38AUZD/E
Air Cooled Condensing Units, 60 Hz
Single Circuit, 2---Stage with Digital Scroll Compressor
and PuronR(R---410A) Refrigerant
Size 08
Installation, Start---Up
and Service Instructions
TABLE OF CONTENTS
SAFETY CONSIDERATIONS 2....................
Rated Indoor Airflow (cfm) 3.....................
Matching 38AUZD/E08 Model to Evaporator Coil 6...
INSTALLATION 6--16...........................
Jobsite Survey 6................................
Step 1 -- Plan for Unit Location 6..................
Step 2 -- Complete Pre--Installation Checks 6.........
Step 3 -- Prepare Unit Mounting Support 6...........
Step 4 -- Rig and Mount the Unit 6.................
Step 5 -- Determine Refrigerant Line Sizes 7.........
Step 6 -- Complete Refrigerant Piping Connections 8....
Step 7 -- Install Accessories 10....................
Step 8 -- Complete Electrical Connections 10.........
Step 9 -- Wind Baffles for Low Ambient Controls 16...
PRE-START-UP 16...............................
System Check 16...............................
Turn On Crankcase Heater 16.....................
Preliminary Charge 16...........................
START--UP 16 -- 19..............................
Preliminary Checks 16...........................
Start Unit 17...................................
OPERATING SEQUENCE 20......................
Base Unit Controls 20...........................
Indoor (Supply) Fan 20..........................
Cooling, Unit Without Economizer 20..............
Cooling, Unit with Economizer 20.................
Heating 20....................................
ROUTINE SYSTEM MAINTENANCE 20............
Quarterly Inspection (and 30 days after initial start) 20...
Seasonal Maintenance 20........................
SERVICE 21 -- 27................................
Refrigeration System 21.........................
Compressor Oil 21..............................
Servicing Systems on Roofs with
Synthetic Materials 21...........................
Liquid Line Filter Drier 21.......................
Filed Refrigerant Access Ports 21..................
Factory High--Flow Access Ports 21................
Comfort Alert Diagnostic Module 22...............
Compressor Protection 24........................
Crankcase Heater 24............................
Low--Pressure Switch 24.........................
High--Pressure Switch 24.........................
Outdoor Fans 24................................
Lubrication 24.................................
Routine Cleaning of Round-Tube Plate Fin
(RTPF) Coils 26................................
Fastener Torque Values 27........................
TROUBLESHOOTING 27 -- 28.....................
APPENDIX A
Air Conditioner & Heat Pump with PuronR—
Quick Reference Guide 29.........................
APPENDIX B
Wiring Diagram List 29...........................
APPENDIX C
Low Ambient Option — Factory Installed 29..........
START--UP CHECKLIST 35 -- 36...................

2
SAFETY CONSIDERATIONS
Improper installation, adjustment, alteration, service,
maintenance, or use can cause explosion, fire, electrical
shock or other conditions which may cause 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 package
Follow all safety codes. Wear safety glasses and work
gloves. Use quenching cloths for brazing operations and
have a fire extinguisher available. Read these instructions
thoroughly and follow all warnings or cautions attached to
the unit. Consult local building codes and appropriate
national electrical codes (in USA, ANSI/NFPA70,
National Electrical Code (NEC); in Canada, CSA C22.1)
for special requirements.
It is important to 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,
CAUTION, and NOTE. These words are used with the
safety-alert symbol. DANGER 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 may 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.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could cause in personal
injury or death.
Before performing service or maintenance operations
on unit, always turn off main power switch to unit and
install lockout tag. Unit may have more than one
power switch.
!WARNING
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this warning could cause in personal
injury,death and/or equipment damage.
PuronR(R--410A) refrigerant systems operate at
higher pressures than standard R--22 systems. Do not
use R--22 service equipment or components on Puron
refrigerant equipment.
!WARNING
PERSONAL INJURY AND ENVIRONMENTAL
HAZARD
Failure to follow this warning could cause in personal
injury or death.
Relieve pressure and recover all refrigerant before
system repair or final unit disposal.
Wear safety glasses and gloves when handling
refrigerants. Keep torches and other ignition sources
away from refrigerants and oils.
!WARNING
CUT HAZARD
Failure to follow this caution may result in personal
injury.
Sheet metal parts may have sharp edges or burrs. Use
care and wear appropriate protective clothing, safety
glasses and gloves when handling parts and servicing
38AU units.
CAUTION
!
38AU

3
Rated Indoor Airflow (cfm)
The table to the right lists the rated indoor airflow used
for the AHRI efficiency rating for the units covered in this
document.
Model Number Full Load Airflow (cfm)
38AUZD/E08 --- 40RUAA*08 3000
Model Type
38AU = Carrier Condensing Unit
Puron®R-410A Refrigerant
Type of Coil
Z = Single Circuit, A/C Scroll Compressor
Refrigerant Options
D = Dual Stage Digital
E = Dual Stage Digital with Low Ambient
Nominal Tonnage
08 = 7.5 Tons
Not Used
A = Not Used
Not Used
0 = Not Used
3Example 8 A U Z D 0 8 A 0 A 6 A 0 A 0 A 0
123456789101112131415161718
Packaging
0 = Standard
1 = LTL
Electrical Options
A = None
C = Non-Fused Disconnect
Service Options
0 = None
1 = Un-powered Convenience Outlet
2 = Powered Convenience Outlet
Not Used
A = PlaceHolder
Design Rev
A = Initial Release
Voltage
1 = 575/3/60
5 = 208/230/3/60
6 = 460/3/60
Coil Options (RTPF)
A = Cu/Al
B = Precoat (Cu/Al)
C = E-Coat (Cu/Al)
E = Cu/Cu
M = Cu/Al with Louvered Hail Guard
N = Precoat (Cu/Al) with Louvered Hail Guard
P = E-Coat (Cu/Al) with Louvered Hail Guard
R = Cu/Cu with Louvered Hail Guard
Base Unit Controls
0 = Electro-Mechanical Controls
Position
C14290
Fig. 1 -- Model Number Nomenclature
38AU

4
C14298
UNIT
STD. UNIT WT. CORNER A CORNER B CORNER C CORNER D CENTER OF GRAVITY UNIT HEIGHT
lbs. kg. lbs. kg. lbs. kg. lbs. kg. lbs. kg. X Y Z H
38AUZD/E08 430 195 142 64 96 44 76 34 111 50 18
[457]
24
[610]
21
[533]
42 3/8
[1076]
Fig. 2 -- 38AUZD/E08 Unit Dimensions
38AU

5
Table 1 – Physical Data
38AUZD/E08 — 60 Hz English
NOMINAL CAPACITY (tons) 7.5
OPERATING WEIGHTS (lb)
Round Tube/Plate Fin Coil (Cu/Al) 430
REFRIGERANT TYPE‡R-410A
RTPF Operating Charge, Typical (lb)†18.0
RTPF Shipping Charge (lb) 14.0
Metering Device TXV
COMPRESSOR
Qty...Type 1...Digital Scroll
Oil Charge (oz) 60
CONDENSER FANS
Qty...Rpm 2...1100
Motor Hp 1/4
Diameter 22
Nominal Airflow (Cfm Total) 6000
Watts (Total) 610
RTPF CONDENSER COIL
Material (Tube/Fin) Cu / Al
Coil Type RTPF
Rows/Fins per inch (FPI) 2/17
Face Area (sq ft total) 23.0
CONTROLS
Pressurestat Settings (psig)
High Cutout 630 10
Cut-in 505 20
Low Cutout 54 3
Cut-in 117 5
PIPING CONNECTIONS (in. ODS)
Qty...Suction 1...1 1/8
Qty...Liquid 1...1/2
LEGEND
RTPF — Round Tube/Plate Fin
ODS — Outside Diameter Sweat (socket)
‡Unit is factory-supplied with partial charge only.
†Typical operating charge with 25 ft of interconnecting piping.
Table 2 – Physical Data
38AUZD/E08 — 60 Hz SI
NOMINAL CAPACITY (kW) 26.4
OPERATING WEIGHTS (lb)
Round Tube/Plate Fin Coil (Cu/Al) 195
REFRIGERANT TYPE‡R-410A
RTPF Operating Charge, Typical (kg)†8.2
RTPF Shipping Charge (kg) 6.4
Metering Device TXV
COMPRESSOR
Qty...Type 1...Digital Scroll
Oil Charge (liters) 1.8
CONDENSER FANS
Qty...r/s 2...18
Motor Hp NEMA 1/4
Diameter (mm) 560
Nominal Airflow (L/s) 2832
Watts (Total) 610
RTPF CONDENSER COIL
Material (Tube/Fin) Cu / Al
Coil Type RTPF
Rows/Fins per Meter (Fins/m) 2 / 670
Face Area (sq m total) 2.1
CONTROLS
Pressurestat Settings (kPa)
High Cutout 4347 70
Cut-in 3482 138
Low Cutout 372 21
Cut-in 80734
PIPING CONNECTIONS (in. ODS)
Qty...Suction 1...1 1/8
Qty...Liquid 1...1/2
LEGEND
RTPF — Round Tube/Plate Fin
NEMA — National Electrical Manufacturers Association
ODS — Outside Diameter Sweat (socket)
‡Unit is factory-supplied with partial charge only.
†Typical operating charge with 25 ft of interconnecting piping.
38AU

6
Matching 38AUZD/E08 Model to Evaporator
Coil
The Model 38AUZD/E08 is a single-circuit, two--stage
unit design, requiring one set of refrigeration piping.
.INSTALLATION
Jobsite Survey
Complete the following checks before installation.
1. Consult local building codes and the NEC (National
Electrical Code) ANSI/NFPA 70 for special installa-
tion requirements.
2. Determine unit location (from project plans) or select
unit location.
3. Check for possible overhead obstructions which may
interfere with unit lifting or rigging.
Step 1 — Plan for Unit Location
The 38AU units are designed and approved for outdoor
installation only. Do not locate these units indoors. Do not
add ducting to unit fan system.
Select a location for the unit and its support system (pad,
rails or other) that provides for the minimum clearances
required for safety. This includes the clearance to
combustible surfaces, unit performance and service access
below, around and above unit as specified in unit drawings.
See Fig. 4.
NOTE: Local codes may require different clearances
than specified in Fig. 4. It is the responsibility of installers
to be knowledgeable in local codes and to modify the
recommended clearances to satisfy local codes.
NOTE: Consider also the effect of adjacent units on
airflow performance and control box safety clearance.
REAR:
Min 18” (457 mm)
requried for service
Note: Observe requirements for 39” (914 mm) operating clearance
on either Left or Rear coil opening.
RIGHT:
Min 18” (457 mm)
requried for service
LEFT:
Min 18” (457 mm)
requried for service
FRONT:
42” (1067 mm)
requried for service
C110201
Fig. 3 -- Service Clearance Dimensional Drawing
Do not install the outdoor unit in an area where fresh air
supply to the outdoor coil may be restricted or when
recirculation from the condenser fan discharge is possible.
Do not locate the unit in a well or next to high walls.
Evaluate the path and required line length for
interconnecting refrigeration piping, including suction
riser requirements (outdoor unit above indoor unit), liquid
line lift (outdoor unit below indoor unit) and hot gas
bypass line. Relocate sections to minimize the length of
interconnecting tubing.
DO NOT BURY REFRIGERATION LINES.
Although unit is weatherproof, avoid locations that permit
water from higher level runoff and overhangs to fall onto
the unit.
Step 2 — Complete Pre-Installation Checks
Check Unit Electrical Characteristics: Confirm before
installation of unit that voltage, amperage and circuit
protection requirements listed on unit data plate agree with
power supply provided.
Un--crate Unit: Remove unit packaging except for the top
skid assembly, which should be left in place until after the
unit is rigged into its final location.
Inspect Shipment: File a claim with shipping company if
the shipment is damaged or incomplete.
Consider System Requirements:
SConsult local building codes and National Electrical Code
(NEC, U.S.A.) for special installation requirements.
SAllow sufficient space for airflow clearance, wiring,
refrigerant piping, and servicing unit. See Fig. 2 for unit
dimensions and weight distribution data.
SLocate the unit so that the outdoor coil (condenser)
airflow is unrestricted on all sides and above.
SThe unit may be mounted on a level pad directly on the
base channels or mounted on raised pads at support
points. See Tables 1 and 2 for unit operating weights.
See Fig. 2 for weight distribution based on
recommended support points.
NOTE: If vibration isolators are required for a particular
installation, use the data in Fig. 2 to make the proper
selection.
Step 3 — Prepare Unit Mounting Support
Slab Mount —
Provide a level concrete slab that extends a minimum of 6
in. (150 mm) beyond unit cabinet. Install a gravel apron in
front of condenser coil air inlet to prevent grass and
foliage from obstructing airflow.
Step 4 — Rig and Mount the Unit
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage.
All panels must be in place when rigging. Unit is not
designed for handling by fork truck.
CAUTION
!
Rigging: These units are designed for overhead rigging.
Refer to the rigging label for preferred rigging method.
38AU

7
Spreader bars are required. Use the wooden top skid,
when rigging, to prevent rigging straps from damaging the
unit. All panels must be in place when rigging. As further
protection for coil faces, plywood sheets may be placed
against the sides of the unit, behind cables. Run cables to
a central suspension point so that the angle from the
horizontal is not less than 45 degrees. Raise and set the
unit down carefully.
If it is necessary to roll the unit into position, mount the
unit on longitudinal rails, using a minimum of 3 rollers.
Apply force to the rails, not the unit. If the unit is to be
skidded into position, place it on a large pad and drag it
by the pad. Do not apply any force to the unit.
Raise from above to lift the unit from the rails or pad
when unit is in its final position.
After the unit is in position, remove all shipping materials
and top crating.
Step 5 — Determine Refrigerant Line Sizes
Select the recommended line sizes for the 38AUZ unit
from the Table 3.
Determine the linear length of interconnecting piping
required between the outdoor unit and indoor unit
(evaporator). Consider and identify also the arrangement
of the tubing path (quantity and type of elbows in both
lines), liquid line solenoid size, filter drier and any other
refrigeration specialties located in the liquid line. Refer to
the indoor unit installation instructions for additional
details on refrigeration specialties devices.
Determine equivalent line length adjustments for path and
components and add to linear line lengths. See Table 4,
Equivalent Lengths for Common Fittings, for usual fitting
types. Also identify adjustments for refrigeration
specialties. Refer to Part 3 of the Carrier System Design
Manual for additional data and information on equivalent
lengths.
Table3–38AUZD/E08PipingRecommendations
Model &
Nominal
capacity
Linear Line (ft) 0 --- 2 5 25 --- 50 50 --- 75 75 --- 100 100 --- 125
Linear Line (m) 0 --- 8 8 --- 1 5 15 --- 23 23 --- 30 30 --- 38
Equiv. Line (ft) 0 --- 3 8 38 --- 75 75 --- 113 113 --- 150 150 --- 188
Equiv. Line (m) 0 --- 1 2 12 --- 23 23 --- 34 34 --- 46 46 --- 57
38AUZ(D,E)08
Liquid Line size 1/2”1/2”5/8”1/2”5/8”1/2”5/8”1/2”5/8”
Liquid PD (_F) 0.6 1.3 0.3 1.9 0.5 2.5 0.7 3.2 0.9
Max Lift 25 50 50 75 75 100 100 97 97
Max Lift PD (_F) 2.7 5.4 4.5 8.1 6.7 10.8 9.0 11.2 8.9
Suction Line size 7/8”7/8” 1 1/8”7/8” 1 1/8” 1 1/8” 1 1/8” 1 3/8”
SuctionLnPD(_F) 1.5 3.1 0.8 4.6 1.2 1.6 2.1 0.7
Charge (lbs) 15.0 18.4 19.1 20.2 23.5 22.5 26.3 24.5 30.1
#/TR 1.96 2.40 2.49 2.63 3.07 2.93 3.43 3.20 3.93
Legend:
Linear Line Linear tubing length, feet
Equivalent Line Equivalent tubing length, including effects of refrigeration specialties devices
Liquid Line size Tubing size, inches OD.
Max Lift Maximum liquid lift (indoor unit ABOVE outdoor unit only), at maximum permitted pressure drop
Max Lift PD (_F) Pressure drop including Maximum liquid lift value.
Suction Line size Tube size, inches OD
Suction PD (_F) Suction Line Pressure Drop, saturated temperature, _F
(Cap Red) Capacity Reduction caused by suction line PD greater than 2_F
Charge Charge Quantity, lbs.
#/TR Charge to unit capacity ratio, lbs per ton (at 45_FSST,95_FODA)
38AU

8
Table 4 – Equivalent Lengths for Common Fittings (ft)
Nominal
Tube OD
Elbows
90Std 90Lrad 90Street 45Std 45Street
3/81.3 0.8 2.2 0.6 1
1/21.4 0.9 2.3 0.7 1.1
5/81.6 12.5 0.8 1.3
3/41.8 1.2 2.9 0.9 1.5
7/821.4 3.2 0.9 1.6
11/82.6 1.7 4.1 1.3 2.1
13/83.3 2.3 5.6 1.7 3
15/842.6 6.3 2.1 3.4
21/853.3 8.2 2.6 4.5
Nominal
Tube OD
Tees
Branch
Flow
Straight-Thru
No Reduct Reduce 25% Reduce 50%
3/82.6 0.8 1.1 1.3
1/22.7 0.9 1.2 1.4
5/83 1 1.4 1.6
3/43.5 1.2 1.7 1.8
7/841.4 1.9 2
11/851.7 2.3 2.6
13/872.3 3.1 3.3
15/882.6 3.7 4
21/810 3.3 4.7 5
NOTE: Equivalent line lengths will vary based on tube
diameter. Calculate equivalent line length for each pipe by
adding equivalent length adjustments to linear lengths for
each pipe.
Liquid Lift —
A liquid lift condition exists when the outdoor unit is located
below the indoor (evaporator) unit and liquid flows vertically
up in a portion of the liquid line. The vertical column of
liquid reduces the available state point subcooling at the
evaporator coil’s thermal expansion valve. This effect
reduces the length of liquid lift (feet of elevation) that a
liquid line size can accommodate. Longer linear tube lengths
will also reduce the amount of liquid lift possible.
Check Table 3 for maximum liquid lift capabilities for line
sizes. Reselect the liquid line tube size if necessary. If
maximum available tube size cannot provide the required lift
distance on this installation, relocate the outdoor unit to
reduce the equivalent line length or the lift requirement.
Suction Riser —
A suction riser condition exists when the outdoor unit is
located above the indoor (evaporator) unit and suction
vapor must flow vertically up to return to the compressor.
Oil return is a concern when the suction tube size is too
large to produce the minimum refrigerant velocity to
ensure oil return at minimum load conditions.
Check Table 5 for maximum suction tube size for
38AUZD/E08 units at minimum load conditions. Consider
suction speed riser (reduced tube size for vertical segment
only) (see Fig. 4) or double suction riser arrangement (see
Fig. 5) if the planned suction tube size does not provide
necessary minimum flowrates for this riser.
Tabl e 5 – 38AU Maximum Suction Pipe Size
Model: Unit Size Maximum Tube Size
38AUZD/E 08 15/8
CONDENSING
UNIT
20-FT (6.1 M) MAX
A
A - Suction Riser Without Trap
LEGEND
S - Suction Line to Condensing Unit
S
C12404
Fig. 4 -- Suction Line Piping -- Speed Riser
FROM
EVAPORATOR
A
A - Suction Riser Without Trap
B - Suction Riser With Trap
S - Suction Line to Condensing Unit
LEGEND
B
S
S
C12405
Fig. 5 -- Suction Line Piping -- Double Riser
Vertical Separation (outdoor unit above indoor unit) –
Vertical elevation difference of 200 ft (60 m) is permitted
when the outdoor unit (38AUZ) is located above the
indoor unit.
Step 6 — Complete Refrigerant Piping Connections
IMPORTANT: Do not bury refrigerant piping
underground.
IMPORTANT: A refrigerant receiver is not provided
with the unit. Do not install a receiver.
Provide Safety Relief —
If local codes dictate an additional safety relief device,
purchase locally and install locally. Installation will
require the recovery of the factory shipping charge before
the factory tubing can be cut and the supplemental relief
device is installed.
38AU

9
Table 6 – Refrigerant Specialties Part Numbers
LIQUID LINE
SIZE (in.)
LIQUID LINE
SOLENOID VALVE (LLSV)
LLSV
COIL
SIGHT
GLASS
FILTER
DRIER
1/2EF680035 EF680037 KM680004 KH43LS085
5/8EF680036 EF680037 KM680005 KH43LS087
Check 38AUZD/E08 Model with Evaporator Coil
Connections —
Confirm before installation of unit that the evaporator coil
connections are consistent with the 38AUZD/E08.
Insulate Suction Lines —
Apply closed-cell tubular insulation to all suction lines
between evaporator coil connection and 38AUZD/E08
unit’s suction service valve.
Refer to Table 6 for recommendations on refrigeration
specialties.
Select the filter drier for maximum unit capacity and
minimum pressure drop. Complete the refrigerant piping
from the indoor unit to the outdoor unit before opening
the liquid and suction lines at the outdoor unit.
Install Liquid Line Solenoid Valve —
It is recommended that a solenoid valve be placed in the
main liquid line (see Fig. 6) between the condensing unit
and the evaporator coil. Locate the solenoid valve at the
outlet end of the liquid line, near the evaporator coil
connections, with flow direction arrow pointed at the
evaporator coil. Refer to Table 6. (A liquid line solenoid
valve is required when the liquid line length exceeds 75 ft
[23 m].) This valve prevents refrigerant migration (which
causes oil dilution) to the compressor during the off cycle, at
low outdoor ambient temperatures. Wire the solenoid in
parallel with the compressor contactor coil (see Fig. 6). This
means of electrical control is referred to as solenoid drop
control.
Single Circuit Coil Piping Configuration
For single compressor condensing units
15 DIAMS
MIN 10
DIAMS
8 DIAMS
MIN
INDOOR
COIL CKT
AIRFLOW
TXV
SENSING
BULB
EQUALIZER LINE
SIGHT GLASS
A LOCATION
TXV
FILTER DRIER
A LOCATION
LIQUID LINE
SOLENOID
VALVE
FLOW
C14291
Fig. 6 -- Location of Sight Glass and Filter Drier
Solenoid drop control wiring: Control the power to the
liquid line solenoid through a Solenoid Valve Relay (SVR)
in all units. Use part number HN61PC005 (field--supplied,
installed). 38AUZD/E08 unit requires one SVR.
Evaporator Capacity Control Liquid Line Solenoid
Val ve : Many older unit designs included automatic
capacity controls that sensed changes in suction pressure
and could increase or decrease compressor capacity
automatically as the evaporator load changed. Control
systems were used on these units that had the thermostat’s
second stage contacts control a capacity control liquid line
solenoid valve to open or shutoff a portion of the
evaporator surface without any direct connection to the
compressor circuit.
This form of system capacity staging control is not
possible with 38AU models. If this installation is a retrofit
for a unit that included automatic pressure--operated
unloading, check the existing thermostat and liquid
solenoid valve. When found, convert the evaporator
second stage solenoid control into a drop--solenoid
control.
Selecting an Accumulator –
Because all 38AU models use scroll compressors, an
accumulator is not required. If an accumulator is to be
added, check the accumulator manufacturer’s literature
carefully for indication of its suitability for use with
R--410A; look for minimum working pressure of 200 psig
(1380 kPa). Select the accumulator first on the basis of its
cataloged minimum capacity (tons) to ensure oil return from
the accumulator, then on tube size or holding capacity.
Make Piping Connections —
Piping connections at the 38AUZ unit are ball valves with
stub tube extensions. Do not open the unit service valves
until all interconnecting tube brazing has been completed.
The stub tube connections include 1/4-in SAE service fittings
with Schrader valve cores (see Fig. 7). Before making any
brazed connections to the unit service valves, remove both
Schrader valve caps and cores and save for re-installation.
Connect a source for nitrogen to one of these service fittings
during tube brazing to prevent the formation of copper
oxides inside the tubes at brazed joints.
When connecting the field tubing to the 38AUZ service
valves, wrap the valves in wet rags to prevent overheating.
Pressure-test all joints from outdoor unit connections over
to the evaporator coil, using nitrogen as pressure and with
soap-and-bubbles.
When pressure-testing is completed, remove the nitrogen
source at the outdoor unit service valves and re-install the
two Schrader valve cores. Torque the cores to 2-3 in-lbs
(23-34 N-cm).
38AU

10
Factory
High-Flow
A
ccess Port
Service Valve
with Stem Cap
Field Service
Access Port
(Schrader core)
Sweat
Connection
C10203
Fig. 7 -- Typical Piping Connection Assembly
Evacuation/Dehydration —
Evacuate and dehydrate the connected refrigeration
system(s) (excluding the 38AUZ unit) to 500 microns
using a two-stage vacuum pump attached to the service
ports outside the 38AU service valves, following
description in GTAC II, Module 4, System Dehydration.
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this warning could cause personal
injury, death and/or equipment damage.
PuronR(R--410A) refrigerant systems operate at
higher pressure than standard R--22 systems. Do not
use R--22 service equipment or components on Puron
refrigerant equipment.
!WARNING
This unit is designed for use with Puron (R--410A)
refrigerant. Do not use any other refrigerant in this system.
Puron (R--410A) refrigerant is provided in pink (rose)
colored cylinders. These cylinders are available with and
without dip tubes; cylinders with dip tubes will have a
label indicating this feature. For a cylinder with a dip
tube, place the cylinder in the upright position (access
valve at the top) when removing liquid refrigerant for
charging. For a cylinder without a dip tube, invert the
cylinder (access valve on the bottom) when removing
liquid refrigerant.
Because Puron (R--410A) refrigerant is a blend, it is strongly
recommended that refrigerant always be removed from the
cylinder as a liquid. Admit liquid refrigerant into the system
in the discharge line. If adding refrigerant into the suction
line, use a commercial metering/expansion device at the
gauge manifold; remove liquid from the cylinder, pass it
through the metering device at the gauge set and then pass it
into the suction line as a vapor. Do not remove Puron
(R--410A) refrigerant from the cylinder as a vapor.
Preliminary Charge —
Before starting the unit, charge R-410A liquid refrigerant
into the high side of each 38AU circuit through the liquid
service valve(s). The amount of refrigerant added must be
at least 80% of the operating charge listed in Table 3 for
LINEAR line length LESS the factory charge quantity (if
factory shipping charge has not been removed). See
example below.
Allow high and low side pressures to equalize. If pressures
do not equalize readily, charge R-410A vapor (using spe-
cial service manifold with expansion device) into the suc-
tion line service port for the low side of system to assure
charge in the evaporator. Refer to GTAC II, Module 5,
Charging, Recover, Recycling, and Reclamation for liquid
charging procedures.
Example:
38AUZ*08 (RTPF)
60-ft (18.3 m) linear line length
Equivalent line length 90-ft (27.4 m)
Liquid Lift: 20-ft (6.1 m)
Select line sizes from Table 3 (38AUZ):
Liquid 1/2in
Suction 1 1/8in.
Charge 22.5 lbs (at 75--ft linear length)
80% of Operating Charge:
0.80 x 22.5 = 18 lbs
Factory Shipping Charge: 14 lbs
Field-Charge quantity: 18 -- 14 = 4 lbs
For linear line lengths longer than 125 ft (38 m), contact
your local Carrier representative for system charge value.
Step 7 — Install Accessories
Accessories requiring modifications to unit wiring should
be completed now. These accessories may include Winter
Start controls and Low Ambient controls. Refer to the
instructions shipped with the accessory.
Step 8 — Complete Electrical Connections
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury or death.
Do not use gas piping as an electrical ground. Unit
cabinet must have an uninterrupted, unbroken electrical
ground to minimize the possibility of personal injury if
an electrical fault should occur. This ground may consist
of electrical wire connected to unit ground lug in control
compartment, or conduit approved for electrical ground
when installed in accordance with NEC (National
Electrical Code); ANSI/NFPA 70, latest edition (in
Canada, Canadian Electrical Code CSA [Canadian
Standards Association] C22.1), and local electrical
codes.
!WARNING
NOTE: Check all factory and field electrical connections
for tightness. Field-supplied wiring shall conform with the
limitations of 63F(33C) rise.
38AU

11
Field Power Supply —
If equipped with optional Powered Convenience Outlet:
The power source leads to the convenience outlet’s
transformer primary are not factory connected. Installer
must connect these leads according to required operation
of the convenience outlet. If an always-energized
convenience outlet operation is desired, connect the
source leads to the line side of the unit-mounted
disconnect. (Check with local codes to ensure this method
is acceptable in your area.) If a de-energize via unit
disconnect switch operation of the convenience outlet is
desired, connect the source leads to the load side of the
unit disconnect. On a unit without a unit-mounted
disconnect, connect the source leads to compressor
contactor C and indoor fan contactor IFC pressure lugs
with unit field power leads..
Refer to Fig. 13 for power transformer connections and the
discussion on connecting the convenience outlet on page 12.
Field power wires are connected to the unit at line-side
pressure lugs on compressor contactor C and TB1 (see
wiring diagram label for control box component
arrangement) or at factory-installed option non-fused
disconnect switch. Max wire size is #4 AWG (copper only).
NOTE: TEST LEADS - Unit may be equipped with short
leads (pigtails) on the field line connection points on
contactor C or optional disconnect switch. These leads are
for factory run-test purposes only; remove and discard
before connecting field power wires to unit connection
points. Make field power connections directly to line
connection pressure lugs only.
FIRE HAZARD
Failure to follow this warning could cause in personal
injury, death and/or equipment damage.
Do not connect aluminum wire between disconnect
switch and condensing unit. Use only copper wire.
(See Fig. 8.)
!WARNING
COPPER
WIRE ONLY
ELECTRIC
DISCONNECT
SWITCH
ALUMINUM
WIRE
A93033
Fig. 8 -- Disconnect Switch and Unit
Units with Factory-Installed Non--Fused Disconnect —
The factory--installed option non--fused disconnect (NFD)
switch is located in a weatherproof enclosure located
under the main control box. The manual switch handle and
shaft are shipped in the disconnect enclosure. Assemble the
shaft and handle to the switch at this point. Discard the
factory test leads (see Fig. 9).
11 13
L1 L2 L3
CTB1
208/230-3-60
460-3-60
575-3-60
Units Without Disconnect Option
Units With Disconnect Option
2
4
6
1
3
5
L1
L2
L3
Optional
Disconnect
Switch
Disconnect factory test leads; discard.
Factory
Wiring
Disconnect
per
NEC
C10204
Fig. 9 -- Power Wiring Connections
Connect field power supply conductors to LINE side
terminals when the switch enclosure cover is removed to
attach the handle.
C12284
Fig. 10 -- Location of Non--Fused Disconnect Enclosure
To field install the NFD shaft and handle:
1. Remove the unit front pane (see Fig. 2).
2. Remove (3) hex screws on the NFD enclosure -- (2) on
the face of the cover and (1) on the left side cover.
3. Remove the front cover of the NFD enclosure.
4. Make sure the NFD shipped from the factory is at
OFF position (the arrow on the black handle knob is
at OFF).
5. Insert the shaft with the cross pin on the top of the shaft
in the horizontal position.
38AU

12
6. Measure from the tip of the shaft to the top surface of
the black pointer; the measurement should be 3.75 --
3.88 in. (95 -- 99 mm).
7. Tighten the locking screw to secure the shaft to the
NFD.
8. Turn the handle to the OFF position with red arrow
pointing at OFF.
9. Install the handle on to the painted cover horizontally
with the red arrow pointing to the left.
10. Secure the handle to the painted cover with (2) screws
and lock washers supplied.
11. Engaging the shaft into the handle socket, re--install
(3) hex screws on the NFD enclosure.
12. Re--install the unit front panel.
C12279
Fig. 11 -- Handle and Shaft Assembly for NFD
Units Without Factory-Installed
Non--Fused Disconnect —
When installing units, provide a disconnect switch per NEC
(National Electrical Code) of adequate size. Disconnect
sizing data is provided on the unit informative plate. Locate
on unit cabinet or within sight of the unit per national or
local codes. Do not cover unit informative plate if mounting
the disconnect on the unit cabinet.
All Units —
All field wiring must comply with NEC and all local
codes. Size wire based on MCA (Minimum Circuit Amps)
on the unit informative plate. See Fig. 9 and the unit label
diagram for power wiring connections to the unit power
terminal blocks and equipment ground. Maximum wire
size is #2 ga AWG (copper only) per pole on contactors.
Provide a ground-fault and short-circuit over-current
protection device (fuse or breaker) per NEC Article 440
(or local codes). Refer to unit informative data plate for
MOCP (Maximum Over-current Protection) device size.
All field wiring must comply with the NEC and local
requirements.
All units except 208/230-v units are factory wired for the
voltage shown on the nameplate. If the 208/230-v unit is to
be connected to a 208-v power supply, the control
transformer must be rewired by moving the black wire with
the

-in. female spade connector from the 230-v connection
and moving it to the 208-v

-in. male terminal on the
primary side of the transformer. Refer to unit label diagram
for line-side information. Field power wires will be
connected line--side pressure lugs on the power terminal
block or at factory--installed option non--fused disconnect.
NOTE: Check all factory and field electrical connections
for tightness.
Affix the crankcase heater warning sticker to the unit
disconnect switch.
Voltage and Current Balance —
Voltage to compressor terminals during operation must be
within voltage range indicated on unit nameplate. See
Table 7. On 3-phase units, voltages between phases must
be balanced within 2% and the current within 10%. Use
the formula shown in the legend for Table 7, Note 4 (see
page 15) to determine the percent of voltage imbalance.
Operation on improper line voltage or excessive phase
imbalance constitutes abuse and may cause damage to
electrical components. Such operation would invalidate
any applicable Carrier warranty.
Convenience Outlets —
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal
injury or death.
Units with convenience outlet circuits may use
multiple disconnects. Check convenience outlet for
power status before opening unit for service. Locate
its disconnect switch, if appropriate, and open it.
Tag-out this switch, if necessary.
!WARNING
Two types of convenience outlets are offered on 38AU
models: Non-powered and unit-powered. Both types
provide a 125-volt GFCI (ground-fault circuit-interrupter)
duplex receptacle rated at 15-A behind a hinged
waterproof access cover, located on the end panel of the
unit. See Fig. 12.
Control Box
Access Panel
Pwd-CO
Transformer
Convenience
Outlet
GFCI
Pwd-CO
Fuse
Switch
C10936
Fig. 12 -- Convenience Outlet Location
38AU

13
Non-powered type: This type requires the field
installation of a general-purpose 125-volt 15-A circuit
powered from a source elsewhere in the building. Observe
national and local codes when selecting wire size, fuse or
breaker requirements and disconnect switch size and
location. Route 125-v power supply conductors into the
bottom of the utility box containing the duplex receptacle.
Maximum continuous current for this type of convenience
outlet (non--unit powered) must not exceed 8 Amps.
Unit-powered type: A unit-mounted transformer is
factory-installed to stepdown the main power supply voltage to
the unit to 115-v at the duplex receptacle. This option also
includes a manual switch with fuse, located in a utility box and
mounted on a bracket behind the convenience outlet; access is
through the unit’s control box access panel. See Fig. 12.
The primary leads to the convenience outlet transformer are
not factory-connected. Selection of primary power source is
a customer-option. If local codes permit, the transformer
primary leads can be connected at the line-side terminals on
the unit-mounted non-fused disconnect or HACR breaker
switch; this will provide service power to the unit when the
unit disconnect switch or HACR switch is open. Other
connection methods will result in the convenience outlet
circuit being de-energized when the unit disconnect or
HACR switch is open. See Fig. 13.
C10206
UNIT
VOLTAGE
CONNECT
AS
PRIMARY
CONNECTIONS
TRANSFORMER
TERMINALS
208,
230 240 L1: RED + YEL L2: BLU + GRA
H1 + H3
H2 + H4
460 480
L1: RED
Splice BLU + YEL
L2: GRA
H1
H2 + H3
H4
575 600 L1: RED
L2: GRA
H1
H2
Fig. 13 -- Powered Convenience Outlet Wiring
The unit-powered convenience outlet has a 1000 VA rated
transformer. Maximum continuous current must not
exceed 8 Amps.
Test the GFCI receptacle by pressing the TEST button on
the face of the receptacle to trip and open the receptacle.
Check for proper grounding wires and power line phasing
if the GFCI receptacle does not trip as required. Press the
RESET button to clear the tripped condition.
Fuse on power type: The factory fuse is a Bussman
“Fusetron” T-15, non-renewable screw-in (Edison base)
type plug fuse.
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal
injury or death.
Using unit-mounted convenience outlets: Units with
unit-mounded convenience outlet circuits will often
require that two disconnects be opened to de-energize
all power to the unit. Treat all units as electrically
energized until the convenience outlet power is also
checked and de-energization is confirmed. Observe
National Electrical Code Article 210, Branch Circuits,
for use of convenience outlets.
!WARNING
Installing Weatherproof Cover: A weatherproof while in
use cover for the factory installed convenience outlets is
now required by UL standards. This cover cannot be
factory mounted due its depth; it must be installed at unit
installation. For shipment, the convenience outlet is
covered with a blank cover plate.
The weatherproof cover kit is shipped in the unit’s control
box. The kit includes the hinged cover, a backing plate
and gasket.
DISCONNECT ALL POWER TO UNIT AND
CONVENIENCE OUTLET.
Remove the blank cover plate at the convenience outlet;
discard the blank cover.
Loosen the two screws at the GFCI duplex outlet, until
approximately 1/2--in (13 mm) under screw heads are
exposed. Press the gasket over the screw heads. Slip the
backing plate over the screw heads at the keyhole slots
and align with the gasket; tighten the two screws until
snug (do not overtighten).
Mount the weatherproof cover to the backing plate as
shown in Fig. 14. Remove two slot fillers in the bottom of
the cover to permit service tool cords to exit the cover.
Check for full closing and latching.
38AU

14
C09022
Fig. 14 -- Weatherproof Cover Installation
All Units —
Voltage to compressor terminals during operation must be
within voltage range indicated on unit nameplate. See
Table 7. On 3-phase units, voltages between phases must
be balanced within 2% and the current within 10%. Use
the formula shown in the legend for Table 7, Note 4 (see
page 15) to determine the percent of voltage imbalance.
Operation on improper line voltage or excessive phase
imbalance constitutes abuse and may cause damage to
electrical components. Such operation would invalidate
any applicable Carrier warranty.
Field Control Wiring —
38AUZ unit control voltage is 24 v. See Fig. 20 for typical
field control connections and the unit’s label diagram for
field-supplied wiring details. Route control wires to the
38AU unit through the opening in unit’s end panel to the
connections terminal board in the unit’s control box.
Remainder of the system controls connection will vary
according to the specific construction details of the indoor
section (air handler or packaged fan coil). Fig. 15 depicts
typical connections to a Carrier 40RU fan coil unit. Plan
for field connections carefully and install control wiring
correctly per the project plan. Additional components and
supplemental transformer accessory may be required.
The 38AUZ unit requires an external temperature control
device. This device can be a thermostat (field-supplied) or
a PremierLink controller (available as a field-installed
accessory, for use on a Carrier Comfort Network or as a
stand alone control).
Thermostat —
Install a Carrier-approved accessory thermostat according
to installation instructions included with the accessory.
Locate the thermostat accessory on a solid wall in the
conditioned space to sense average temperature in
accordance with the thermostat installation instructions.
The 38AUZD/E08 unit is a single--circuit, two--stage
cooling unit. Select a two--stage cooling thermostat, with
or without supplemental heating, as needed.
(Note 1)
(Note 2)
(Note 2)
Note 1: Connect only if thermostat requires 24-vac power source.
Note 2: Connect W1 and W2 if supplemental heaters are installed
Field Wiring
C14292
Fig. 15 -- Typical Remote Thermostat Connections
Select a thermostat cable or equivalent single leads of
different colors with minimum of five leads for
38AUZD/E08 units. Check the thermostat installation
instructions for additional features which might require
additional conductors in the cable.
For wire runs up to 50 ft. (15 m), use no. 18 AWG
(American Wire Gage) insulated wire (35C minimum).
For50to75ft.(15to23m),useno.16AWGinsulated
wire (35C minimum). For over 75 ft. (23 m), use no. 14
AWG insulated wire (35C minimum). All wire sizes
larger than no. 18 AWG cannot be directly connected to
the thermostat and will require a junction box and splice
at the thermostat.
PremierLink (accessory installation) – Refer to Form
33CS-68SI (or later) for details on connecting the
PremierLink controller and its various sensors.
If the unit will be operating at 208-3-60 power, remove
the black wire (BLK) from the transformer primary
connection labelled “230” and move it to the connection
labelled “208”. See Fig. 16.
C10079
Fig. 16 -- Control Transformer Wiring
38AU

15
External Devices —
The 38AU control transformers provide 24--v NEC Class 2
power sources to energize external control devices. These
devices will include the indoor fan motor contactor (or
control relay). These devices may also include liquid line
solenoid valve, economizer control relay, supplemental
electric heater contactors or control relays and other devices
selected by system designer.
Control transformer TRAN1 provides control power through
terminal R to C on the field connection terminal strip TB for
supply fan motor interlock. This source may also be used to
energize economizer control relay and electric heater
contactors or relays. Maximum available power is 20 va.
Check concurrent loadings by external control devices. If the
maximum concurrent loading exceeds 20 va, purchase and
install the accessory Transformer--Relay package (available
for 208/230 and 460--v units).
Table 7 – Electrical Data — 38AUZD/E08 60 Hz Units
WITH POWERED CONVENIENCE OUTLET
UNIT V --- P h --- H z
VOLTAGE
RANGE}COMPRESSOR OFM (ea) POWER SUPPLY DISCONNECT SIZE
MIN MAX RLA LRA QTY FLA MCA MOCP FLA LRA
38AUZD/E08
208/230--- 3--- 60 187 253 24.0 186 21.5 38 60 37 197
4 6 0 --- 3 --- 6 0 414 506 12.6 100 20.8 20 30 19 106
5 7 5 --- 3 --- 6 0 518 633 9.9 78 20.7 16 25 15 84
WITHOUT POWERED CONVENIENCE OUTLET
UNIT V --- P h --- H z
VOLTAGE
RANGE}COMPRESSOR OFM (ea) POWER SUPPLY DISCONNECT SIZE
MIN MAX RLA LRA QTY FLA MCA MOCP FLA LRA
38AUZD/E08
208/230--- 3--- 60 187 253 24.0 186 21.5 33 50 31 192
4 6 0 --- 3 --- 6 0 414 506 12.6 100 20.8 18 25 16 104
5 7 5 --- 3 --- 6 0 518 633 9.9 78 20.6 14 20 13 82
Legend and Notes for Table 7
LEGEND:
F L A --- F u l l L o a d A m p s
LRA --- Locked Rotor Amps
MOCP --- Maximum Over Current
Protection
NEC --- National Electrical Code
RLA --- Rated Load Amps
}Units are suitable for use on electrical systems where voltage
supplied to the unit terminals is not below or above the listed
limits.
NOTES:
1. The MCA and Fuse values are calculated in accordance with
The NEC. Article 440.
2. Motor RLA and LRA values are established in accordance
with Underwriters’ Laboratories (UL). Standard 1995.
3 . T h e 5 7 5 --- v u n i t s a r e U L , C a n a d a --- l i s t e d o n l y.
4. Unbalanced 3-Phase Supply Voltage
Never operate a motor where a phase imbalance in supply
voltage is greater than 2%. Use the following formula to de-
termine the percentage of voltage imbalance.
Example: Supply voltage is 230-3-60
% Voltage Imbalance = 100 x
max voltage deviation from average voltage
average voltage
AB = 224 v
BC = 231 v
AC = 226 v
Average Voltage =
(224 + 231 + 226)
=
681
33
= 227
Determine maximum deviation from average voltage.
(AB) 227 – 224 = 3 v
(BC) 231 – 227 = 4 v
(AC) 227 – 226 = 1 v
Maximum deviation is 4 v.
Determine percent of voltage imbalance.
% Voltage Imbalance = 100 x
4
227
= 1.76%
This amount of phase imbalance is satisfactory as it is below the
maximum allowable 2%.
IMPORTANT: If the supply voltage phase imbalance is more than
2%, contact your local electric utility company immediately.
38AU

16
Step 9 — Wind Baffles for Low Ambient Control
38AUZE08 includes the factory installed 32LT Motormaster
Low Ambient Control.
Units with 32LT Motormaster control require the addition
of wind baffles to ensure full range low ambient
operation. Material data and dimensions for wind baffles
are included in the Appendix C section, Low Ambient
Control, starting on page 29. Fabricate the wind baffles
and mount per instructions.
PRE-START-UP
IMPORTANT: Before beginning Pre-Start-Up or
Start-Up, review Start-Up Checklist at the back of this
book. The Checklist assures proper start-up of a unit
and provides a record of unit condition, application
requirements, system information, and operation at
initial start-up.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage.
Do not attempt to start the condensing unit, even
momentarily, until the following steps have been
completed. Compressor damage may result.
CAUTION
!
System Check
1. The electrical power source must agree with the unit’s
nameplate rating.
2. Check all air handler(s) and other equipment auxiliary
components. Consult the manufacturer’s instructions re-
garding any other equipment connected to the condens-
ing unit. If the unit has field-installed accessories, be
sure all are properly installed and correctly wired. If
used, the airflow switch must be properly installed.
3. Check tightness of all electrical connections.
4. Be sure liquid line and low side of the system are
properly leak checked and dehydrated.
5. Be sure the unit is properly charged. See “Preliminary
Charge”, below.
6. Open the liquid line and suction line service valves.
7. The crankcase heater must be firmly attached to the
compressor crankcase. Be sure the crankcase is warm
(heater must be on for 24 hours before starting
compressor).
Turn On Crankcase Heater —
Turn on the crankcase heater for 24 hours before starting
the unit to be sure all the refrigerant is out of the oil.To
energize the crankcase heater, proceed as follows:
1. Set the space thermostat set point above the space
temperature so there is no demand for cooling.
2. Close the field disconnect.
Preliminary Charge —
Before starting the unit, charge liquid refrigerant into the
high side of the system through the liquid service valve. The
amount of refrigerant added must be at least 80% of the
operating charge listed in the Physical Data table (Tables 1
and 2 on page 5). Allow high and low side pressures to
equalize before starting compressor. If pressures do not
equalize readily, charge vapor on low side of system to
assure charge in the evaporator. Refer to GTAC II, Module
5, Charging, Recover, Recycling, and Reclamation for liquid
charging procedures.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage.
Prior to starting compressor, a preliminary charge of
refrigerant must be added to avoid possible
compressor damage.
CAUTION
!
START-UP
38AU Units: The compressor crankcase heater must be on
for 24 hours before start-up. After the heater has been on
for 24 hours, the unit can be started. If no time elapsed
since the preliminary charge step was completed, it is
unnecessary to wait the 24-hour period.
Preliminary Checks
1. Check that electric power supply agrees with unit
nameplate data.
2. Verify that the compressor crankcase heater is se-
curely in place.
3. Check that the compressor crankcase heater has been
on at least 24 hours.
4. Recheck for leaks using the procedure outlined in the
Pre-Start-Up section, Leak Test and Dehydration. If
any leaks are detected, repair as required. Evacuate
and dehydrate as described in the Leak Test and De-
hydration section.
5. Ensure that the preliminary charge has been added as
described in the Pre-Start-Up section, Preliminary
Charge.
6. All internal wiring connections must be tight, and all
barriers and covers must be in place.
NOTE: The 38AU units are factory charged with the
required amount of oil. If recharging in required, use
Emkarate RL 32-3MAF for the 38AU units.
Compressor Rotation —
On 3--phase units with scroll compressors, it is important to
be certain that the compressor is rotating in the proper
direction. 38AU units are equipped with a Comfort Alert
Diagnostic Module (CADM). Alert Code 7 indicates reverse
power phasing.
38AU

17
To correct phase order:
1. Turn off power to the unit, tag disconnect.
2. Reverse any two of the unit power leads.
3. Reapply power to the compressor, verify correct
pressures.
To verify the compressor is rotating in the proper
direction:
1. Connect service gages to the suction and liquid pres-
sure fittings.
2. Energize the compressor.
3. The suction pressure should drop and the liquid
pressure should rise, as is normal on any start--up.
Compressor Overload —
This overload interrupts power to the compressor when
either the current or internal motor winding temperature
becomes excessive, and automatically resets when the
internal temperature drops to a safe level. This overload
may require up to 60 minutes (or longer) to reset. If the
internal overload is suspected of being open, disconnect
the electrical power to the unit and check the circuit
through the overload with an ohmmeter or continuity
tester.
Advanced Scroll Temperature Protection (ASTP) —
A label located above the terminal box identifies Copeland
Scroll compressor models that contain this technology. See
Fig. 17. Advanced Scroll Temperature Protection (ASTP) is
a form of internal discharge temperature protection, that
unloads the scroll compressor when the internal temperature
reaches approximately 149_C (300_F). At this temperature,
an internal bi--metal disk valve opens and causes the scroll
elements to separate, which stops compression. Suction and
discharge pressures balance while the motor continues to
run. The longer the compressor runs unloaded, the longer it
must cool before the bi--metal disk resets. See Fig. 18.
To manually reset ASTP, the compressor should be
stopped and allowed to cool. If the compressor is not
stopped, the motor will run until the motor protector trips,
which occurs up to 90 minutes later. Advanced Scroll
Temperature Protection will reset automatically before the
motor protector resets, which may take up to 2 hours.
C10080
Fig. 17 -- Advanced Scroll Temperature Protection Label
0
10
20
30
40
50
60
70
80
90
100
110
120
0 10203040 6070809050
Compressor Unloaded Run Time (Minutes)*
*Times are approximate.
NOTE: Various factors, including high humidity, high ambient
temperature, and the presence of a sound blanket will
increase cool-down times.
Recommended Cooling Time*
(Minutes)
C10081
Fig. 18 -- Recommended Minimum Cool-Down Time
After Compressor is Stopped
Start Unit
Set the space thermostat to a set point above space
temperature so that there is no demand for cooling. Close
the 38AU disconnect switch. Only the crankcase heater
will be energized.
Reset the space thermostat below ambient so that a call
for cooling is ensured.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage.
Never charge liquid into the low-pressure side of
system. Do not overcharge. During charging or
removal of refrigerant, be sure indoor-fan system is
operating. Ensure both outdoor fan motors are
running; bypass any Motormaster function.
CAUTION
!
Adjust Refrigerant Charge —
Refer to Cooling Charging Chart, Fig. 19. For applications
with line lengths greater than 125 ft (38 m), contact Carrier
representative. Vary refrigerant until the conditions of the
chart are met. Note that the charging charts are different
from the type normally used. The charts are based on
charging the units to the correct subcooling for the various
operating conditions. Accurate pressure gage and
temperature sensing device are required. Connect the
pressure gage to the service port on the liquid line service
valve. Mount the temperature sensing device on the liquid
line close to the liquid line service valve, and insulate it so
that outdoor ambient temperature does not affect the reading.
Indoor airflow must be within the unit’s normal operating
range. Operate the unit for a minimum of 15 minutes.
Ensure that pressure and temperature readings have
stabilized. Plot the liquid pressure and temperature on chart
and add or reduce the charge to meet the curve. Adjust the
charge to conform with the charging chart, using the liquid
pressure and temperature to read the chart.
38AU

18
Using plotted operating point:
If plotted operating condition is -- Adjust charge by --
BELOW the curve REDUCE charge
ABOVE the curve ADD charge
Final Checks —
Ensure that all safety controls are operating, control panel
covers are on, and the service panels are in place.
30
50
70
90
110
130
150
140 190 240 290 340 390 440 490 540 590
PRESSURE AT LIQUID VALVE (PSIG)
PRESSION À LA VANNE DE LIQUIDE (PSIG)
7.5 TON DUAL STAGE CHARGING CHART PURON
(COMPRESSOR FULL LOAD, ALL CONDENSER FANS OPERATING)
DIAGRAMME DE REMPLISSAGE DE PURON POUR 7.5 TONNES, 2 STAGE
(COMPRESSEUR À PLEINE CAPACITÉ, TOUS LES VENTILATEURS DU
CONDENSEUR EN OPÉRATION)
38AU000028 Rev -
TEMPERATURE AT LIQUID VALVE (°F)
TEMPÉRATURE À LA VANNE DE LIQUIDE (°F)
C14293
Fig. 19 -- 38AUZD/E08 Charging Chart
38AU

19
C14294
Fig. 20 -- Typical 38AUZD/E08 Wiring Diagram -- 208/230V--3PH--60Hz Unit Shown
38AU

20
OPERATING SEQUENCE
Base Unit Controls
Indoor (Supply) Fan —
The indoor fan contactor (IFC) is remotely located at the fan
coil or fan section. If the thermostat fan operation is selected
as Continuous, the IFC is energized and the indoor (supply)
fan motor runs continuously. If the thermostat fan operation
is selected as Automatic, the IFC will be energized on a call
for Cooling; indoor (supply) fan motor runs. When
thermostat call for Cooling is satisfied, the IFC is
de-energized and indoor (supply) fan motor stops.
Cooling, Unit Without Economizer —
On a thermostat call for Cooling, IFC will be energized
and indoor (supply) fan motor runs. Thermostat output Y1
is energized; terminal Y1 at 38AUZ unit receives 24-v.
24-v received at CADM1 terminal Y. If anti-recycle time
delay period has not expired, CADM1 relay will remain
open, de-energizing Solenoid Valve Relay (SVR) and
preventing compressor start. When safety pressure
switches are closed and CADM1 time delay expires,
CADM1 relay closes, SVR and compressor contactor C1
are energized; Compressor Relay Timer (CTR) is closed
and Digital Cycle Timer (CTD) is energized commanding
Digital Compressor Solenoid (DCS) on, liquid line
solenoid valve LLSV opens, all outdoor fan motors start
and Compressor starts part load operation.
On thermostat call for Stage 2 Cooling, thermostat output
Y2 is energized CTR receives 24--v at terminal 1 changing
contacts to open. CTD is de--energized and commands
DCS off, Compressor operates at full load.
As space cooling load is satisfied, thermostat outputs Y2 and
Y1 are sequentially de--energized, removing 24--v at 38AUZ
terminals Y1 and Y2. Compressor resumes part load
operation on Y2 opening. On Y1 opening, Compressor 1
stops, all outdoor fan motors stop and SVR is de--energized.
Liquid Line solenoid valve is de--energized and valve closes.
CADM1 begins its three--minute anti--recycle time delay.
If either the Low Pressure Switch or High Pressure Switch
opens while thermostat output Y1 or Y2 remain energized,
the compressor contactor is de-energized, the compressor
stops and liquid line solenoid is de-energized (valve
closes). CADM initiates a TRIP event (cooling demand
sensed at CADM terminal Y but no current is measured at
T1, T2, T3 motor sensors); CADM relay opens and RED
LED is illuminated. TRIP condition maintains lockout of
compressor operation until CADM is manually reset.
Reset CADM by cycling unit main power.
Complete system shutdown may be caused by loss of
main power, open compressor internal overload, open
low-pressure or high-pressure switch, or a fault detected
by the CADM logic. Compressor operation without
cooling may indicate the compressor’s ASTP feature is
active; disconnect unit power and allow compressor to
cool. See Service section for further details.
Cooling, Unit With Economizer —
Refer to fan coil unit installation instructions and
economizer accessory installation instructions for
operating sequences when system is equipped with
accessory economizer.
Heating —
Refer to fan coil unit installation instructions and accessory
heating device installation instructions for operating
sequences in heating mode.
ROUTINE SYSTEM MAINTENANCE
These items should be part of a routine maintenance
program, to be checked every month or two, until a specific
schedule for each can be identified for this installation:
Quarterly Inspection (and 30 days after initial start) —
Indoor section
SCondenser coil cleanliness checked.
SReturn air filter replacement
SOutdoor hood inlet filters cleaned
SBelt tension checked
SBelt condition checked
SPulley alignment checked
SFan shaft bearing locking collar tightness checked
SCondensate drain checked
Seasonal Maintenance —
These items should be checked at the beginning of each
season (or more often if local conditions and usage patterns
dictate):
Air Conditioning
SCondenser fan motor mounting bolts tightness
SCompressor mounting bolts
SCondenser fan blade positioning
SControl box cleanliness and wiring condition
SWire terminal tightness
SRefrigerant charge level
SEvaporator coil cleaning
SEvaporator blower motor amperage
Heating
SPower wire connections
SFuses ready
SManual-reset limit switch is closed
Economizer or Outside Air Damper
SInlet filters condition
SCheck damper travel (economizer)
SCheck gear and dampers for debris and dirt
38AU