AAON CL SERIES Owner's manual

CL SERIES
Condensing Units
Installation, Operation
& Maintenance

2
Table of Contents
Safety ............................................................................................................................................................. 6
CL Series Feature String Nomenclature...................................................................................................... 11
GENERAL DESCRIPTION........................................................................................................................ 14
Unpacking:............................................................................................................................................... 14
OWNER'S INFORMATION....................................................................................................................... 14
Warning: .................................................................................................................................................. 14
Wiring Diagrams:..................................................................................................................................... 15
General Maintenance:.............................................................................................................................. 15
INSTALLATION ........................................................................................................................................ 15
Lifting and Handling:............................................................................................................................... 15
Condenser Placement:.............................................................................................................................. 15
Compressor Compartment Exhaust Fan:................................................................................................. 15
Mounting Isolation:.................................................................................................................................. 16
Access Doors: .......................................................................................................................................... 16
Standard Evacuation Instructions: ........................................................................................................... 16
Low Ambient & Modulating Reheat System Evacuation Instructions:................................................... 17
Charging Refrigerant: .............................................................................................................................. 18
Before Charging:...................................................................................................................................... 18
Checking Liquid Sub-cooling:................................................................................................................. 19
Checking Evaporator Superheat: ............................................................................................................. 19
Special Low Ambient Charging Instructions:.......................................................................................... 20
Low Ambient Operation:......................................................................................................................... 20
LAC Valve:.............................................................................................................................................. 21
Electrical.................................................................................................................................................. 22
Refrigerant Piping Connections:.............................................................................................................. 24
Evaporative Condenser Field Piping Connections: ................................................................................. 24
STARTUP.................................................................................................................................................... 26
Pre-Startup:.............................................................................................................................................. 26
Startup:..................................................................................................................................................... 26
Axial Flow Fans:...................................................................................................................................... 27
Insert Blades: ........................................................................................................................................... 28
SERVICING AND MAINTENANCE........................................................................................................ 29
General:.................................................................................................................................................... 29
Compressors:............................................................................................................................................ 29
Refrigerant Suction Line Filter:............................................................................................................... 29
Suction Filter Removal Instructions ........................................................................................................ 29
Refrigerant Liquid Line Filter Driers:...................................................................................................... 30
Evaporator/Heat Exchangers: .................................................................................................................. 30
Lubrication:.............................................................................................................................................. 30
Service Information: ................................................................................................................................ 30
Replacement Parts:................................................................................................................................... 30
AAON Technical Support........................................................................................................................ 30
Severe Service:......................................................................................................................................... 31
Safety:...................................................................................................................................................... 31
Performance:............................................................................................................................................ 32
Warranties:............................................................................................................................................... 32
Condenser Tube Inspection: .................................................................................................................... 32

3
Freeze Protection: .................................................................................................................................... 32
Recirculating Water System: ................................................................................................................... 32
EVAPORATIVE CONDENSER - PRE START-UP.................................................................................. 32
Cleanliness:.............................................................................................................................................. 32
Pump Operation:...................................................................................................................................... 32
Running:................................................................................................................................................... 32
Condenser Fan Motors:............................................................................................................................ 33
Water Make-up Valve:............................................................................................................................. 33
Water Treatment System: ........................................................................................................................ 34
Sequence of Operation:............................................................................................................................ 34
EVAPORATIVE CONDENSER - MAINTENANCE REQUIREMENTS................................................ 35
Pump Maintenance: ................................................................................................................................. 35
Fan Motor Maintenance:.......................................................................................................................... 35
Access Doors: .......................................................................................................................................... 35
Bearings - Lubrication:............................................................................................................................ 35
Required Monthly Inspection: ................................................................................................................. 35
Mist Eliminators: ..................................................................................................................................... 35
Air Inlet:................................................................................................................................................... 35
Stainless Steel Base Pan: ......................................................................................................................... 35
Propeller Fans and Motors:...................................................................................................................... 35
Required Annual Inspection: ................................................................................................................... 35
Cleaning:.................................................................................................................................................. 35
EVAPORATIVE CONDENSER - WATER QUALITY............................................................................ 36
Recirculating Water Quality Guidelines:................................................................................................. 36
Mechanical Cleaning: .............................................................................................................................. 36
Parts: ........................................................................................................................................................ 36
AIR-COOLED CONDENSER.................................................................................................................... 36
E-Coated Coil Cleaning........................................................................................................................... 36
REFRIGERANT PIPING FOR THE CL SERIES...................................................................................... 39
General:.................................................................................................................................................... 39
Determining Refrigerant Line size: ......................................................................................................... 39
Equivalent Line Length: .......................................................................................................................... 39
Liquid line sizing:.................................................................................................................................... 40
Liquid Line Routing:................................................................................................................................ 40
Liquid Line Insulation: ............................................................................................................................ 40
Liquid Line Guidelines:........................................................................................................................... 40
Liquid Line Accessories: ......................................................................................................................... 40
Suction Line Sizing:................................................................................................................................. 40
Suction Line Routing:.............................................................................................................................. 40
Suction Line Traps:.................................................................................................................................. 41
Suction Line Insulation:........................................................................................................................... 41
Suction Line Guidelines:.......................................................................................................................... 41
Suction Line Accessories:........................................................................................................................ 42
Hot Gas Bypass Line: .............................................................................................................................. 42
Hot Gas Bypass Piping Considerations for Evaporator Above Condensing Unit:.................................. 42
Hot Gas Bypass Piping Considerations for Evaporator Below Condensing Unit:.................................. 42
Hot Gas Bypass Line Guidelines:............................................................................................................ 42
Hot Gas Reheat Line:............................................................................................................................... 42

4
Hot Gas Reheat Line Guidelines: ............................................................................................................ 43
Literature Change History........................................................................................................................ 58
Index of Tables and Figures
Tables:
Table 1 - Service Clearances........................................................................................................................ 15
Table 2 - Acceptable Refrigerant Circuit Values......................................................................................... 19
Table 3 - % Charge to Flood Condenser Coil for Ambient Below 70°F..................................................... 20
Table 4 - Nameplate Voltage Markings & Tolerances................................................................................ 22
Table 5 - Liquid Line Filter Drier Pressure Drop........................................................................................ 30
Table 6 - Water Quality ............................................................................................................................... 36
Figures:
Figure 1 - CU evacuation connections......................................................................................................... 16
Figure 2 - CU evacuation connections......................................................................................................... 17
Figure 3 - AHU evacuation connections...................................................................................................... 18
Figure 4 - Piping Schematic of Example system using the LAC valve....................................................... 21
Figure 5 - Refrigerant Piping Connections.................................................................................................. 24
Figure 6 - Evaporative Condenser Section Water Treatment Components................................................. 25
Figure 7 - Water Level Sensor..................................................................................................................... 33
Figure 8 - Double Suction Riser .................................................................................................................. 41
Figure 9 - Oil Return Piping ........................................................................................................................ 42
Figure 10 - Hot Gas Bypass Piping Diagram with air handler above condenser ........................................ 44
Figure 11 - Hot Gas Bypass Piping Diagram with air handler below condenser........................................ 45
Figure 12 - Hot Gas Reheat Piping Diagram with air handler above condenser......................................... 46
Figure 13 - Hot Gas Reheat Piping Diagram with air handler below condenser......................................... 47
Figure 14 - Hot Gas Reheat Piping Diagram with air handler above condenser and field installed suction
line accumulator........................................................................................................................................... 48
Figure 15 - Hot Gas Reheat Piping Diagram with air handler above condenser and field installed suction
line accumulator........................................................................................................................................... 49
Figure 16 - Reheat/Hot Gas Bypass Piping Diagram with air handler above condenser............................ 50
Figure 17 - Reheat/Hot Gas Bypass Piping Diagram with air handler below condenser............................ 51
Figure 18 - Reheat/Hot Gas Bypass Piping Diagram with air handler evaporator above condenser and field
installed suction line accumulator................................................................................................................ 52
Figure 19 - Reheat/Hot Gas Bypass Piping Diagram with air handler below condenser and field installed
suction line accumulator.............................................................................................................................. 53
R10110 · Rev. C · 200910

5
AAON®CL Series Features and Options Introduction
Energy Efficiency
Air-Cooled or Energy Saving Evaporative
Condenser
Direct Expansion Systems
Tandem Scroll Compressors
VFD Controlled Condenser Fans
Humidity Control
Modulating Hot Gas Reheat
Safety
Phase and Brownout Protection
Automatic Low Pressure and Manual Reset
High Pressure Safety Cut-outs
Schrader Valves
Internal Overload Protection on Tandem
Scroll Compressors
Aluminum Tread Plate Floor Covering
Compressor Isolation Valves
Installation and Maintenance
Access Doors with Hinges, Lockable Handles
and Rain Gutters
Walk-In Weatherproof Compressor
Compartment
Run Test Report and Installation Manuals
Included in Controls Compartment
Color Coded Wiring and Wiring Diagrams
Double Pane Viewing Windows
Compressors are Deck Mounted with Rubber
Isolation
Three-Chemical Water Treatment System for
Evaporative Condenser
Aluminum Tread Plate Floor
Foam Insulated Double Wall Construction
Replaceable Core Filter Driers
System Integration
Single Point Power Connection
Air-Cooled or Evaporative Condensers
Environmentally Friendly
R-410A Refrigerant
Extended Life
2,500 Hour Salt Spray Tested Exterior
Corrosion Paint
Optional 5 Year Non-Prorated Compressor
Warranty
Sloped Condenser Coils with Outer Protection

6
Safety
Attention must be paid to the following statements:
NOTE - Notes are intended to clarify the unit installation, operation and maintenance.
CAUTION - Caution statements are given to prevent actions that may result in equipment
damage, property damage, or personal injury.
WARNING - Warning statements are given to prevent actions that could result in
equipment damage, property damage, personal injury or death.
DANGER - Danger statements are given to prevent actions that will result in equipment
damage, property damage, severe personal injury or death.
QUALIFIED INSTALLER
Improper installation, adjustment,
alteration, service or maintenance can
cause property damage, personal
injury or loss of life. Startup and
service must be performed by a
Factory Trained Service Technician. A
copy of this IOM must be kept with the
unit.
WARNING
ELECTRIC SHOCK, FIRE OR
EXPLOSION HAZARD
Failure to follow safety warnings
exactly could result in dangerous
operation, serious injury, death or
property damage.
Improper servicing could result in
dangerous operation, serious injury,
death, or property damage.

When servicing controls, label all
wires prior to disconnecting.
Reconnect wires correctly.

Verify proper operation after
servicing. Secure all doors with
key-lock or nut and bolt.
WARNING
ELECTRIC SHOCK
Electric shock hazard. Before
servicing, shut off all electrical power
to the unit, including remote
disconnects, to avoid shock hazard or
injury from rotating parts. Follow
proper Lockout-Tagout procedures.
WARNING

7
ROTATING COMPONENTS
Unit contains fans with moving parts
that can cause serious injury. Do not
remove grill containing fans until the
power to the unit has been
disconnected and fan has stopped
rotating.
WARNING
LIVE ELECTRICAL
During installation, testing, servicing,
and troubleshooting of the equipment
it may be necessary to work with live
electrical components. Only a
qualified licensed electrician or
individual properly trained in handling
live electrical components shall
perform these tasks.
Standard NFPA-70E, an OSHA
regulation requiring an Arc Flash
Boundary to be field established and
marked for identification of where
appropriate Personal Protective
Equipment (PPE) be worn, must be
followed.
WARNING
FIRE, EXPLOSION OR CARBON
MONOXIDE POISONING HAZARD
Failure to replace proper controls
could result in fire, explosion or
carbon monoxide poisoning. Failure to
follow safety warnings exactly could
result in serious injury, death or
property damage. Do not store or use
gasoline or other flammable vapors
and liquids in the vicinity of this
appliance.
WARNING
GROUNDING REQUIRED
All field installed wiring must be
completed by qualified personnel.
Field installed wiring must comply with
NEC/CEC, local and state electrical
code requirements. Failure to follow
code requirements could result in
serious injury or death. Provide proper
unit ground in accordance with these
code requirements.
WARNING
VARIABLE FREQUENCY DRIVES
Do not leave VFDs unattended in
hand mode or manual bypass.
Damage to personnel or equipment
can occur if left unattended. When in
hand mode or manual bypass mode
VFDs will not respond to controls or
alarms.
WARNING

8
LEAK TESTING
Do not use oxygen, acetylene or air in
place of refrigerant and dry nitrogen
for leak testing. A violent explosion
may result causing injury or death.
WARNING
VARIABLE FREQUENCY DRIVES
Electric motor over-current protection
and overload protection may be a
function of the Variable Frequency
Drive to which the motors are wired.
Never defeat the VFD motor overload
feature. The overload ampere setting
must not exceed 115% of the electric
motors FLA rating as shown on the
motor nameplate.
CAUTION
PVC PIPING
PVC (Polyvinyl Chloride) and CPVC
(Chlorinated Polyvinyl Chloride) are
vulnerable to attack by certain
chemicals. Polyolester (POE) oils
used with R-410A and other
refrigerants, even in trace amounts, in
a PVC or CPVC piping system will
result in stress cracking of the piping
and fittings and complete piping
system failure.
CAUTION
3-PHASE ROTATION
Rotation must be checked on all
MOTORS AND COMPRESSORS of 3
phase units at startup by a qualified
service technician. Scroll
compressors are directional and can
be damaged if rotated in the wrong
direction. Compressor rotation must
be checked using suction and
discharge gauges. Fan motor rotation
must be checked for proper operation.
Alterations must only be made at the
unit power connection
CAUTION
UNIT HANDLING
To prevent injury or death lifting
equipment capacity shall exceed unit
weight by an adequate safety factor.
Always test-lift unit not more than 24
inches high to verify proper center of
gravity lift point to avoid unit damage,
injury or death.
WARNING
DOOR LATCHES
Door compartments containing
hazardous voltage or rotating parts
are equipped with door latches that
allow locks. Door latches are shipped
with a nut and bolt requiring tooled
access. If the shipping hardware is not
replaced with a pad lock, always re-
install the nut and bolt after closing the
door to maintain tooled access.
CAUTION

9
ENCLOSED AREA
Do not work in an enclosed area
where refrigerant or nitrogen gases
may be leaking. A sufficient quantity of
vapors may be present and cause
injury or death.
WARNING
COMPRESSOR LUBRICANT
Polyolester (POE) and Polyvinylether
(PVE) oils are two types of lubricants
used in hydrofluorocarbon (HFC)
refrigeration systems. Refer to the
compressor label for the proper
compressor lubricant type.
CAUTION
COIL CLEANERS
To prevent damage to the unit, do not
use acidic chemical coil cleaners. Do
not use alkaline chemical coil cleaners
with a pH value greater than 8.5, after
mixing, without first using an
aluminum corrosion inhibitor in the
cleaning solution.
CAUTION
COIL CLEANERS
Some chemical coil cleaning
compounds are caustic or toxic. Use
these substances only in accordance
with the manufacturer’s usage
instructions. Failure to follow
instructions may result in equipment
damage, injury or death.
WARNING
COIL CLEANING
Do not clean DX refrigerant coils with
hot water or steam. The use of hot
water or steam on refrigerant coils will
cause high pressure inside the coil
tubing and damage to the coil.
CAUTION
CONVENIENCE OUTLETS
Factory installed convenience outlets
are not intended for use while the unit
is operating.
WARNING

10
1. Startup and service must be performed by
a Factory Trained Service Technician.
2. The unit is for outdoor use only. See
General Information section for more
information.
3. Every unit has a unique equipment
nameplate with electrical, operational,
and unit clearance specifications.
Always refer to the unit nameplate for
specific ratings unique to the model
purchased.
4. READ THE ENTIRE INSTALLATION,
OPERATION AND MAINTENANCE
MANUAL. OTHER IMPORTANT
SAFETY PRECAUTIONS ARE
PROVIDED THROUGHOUT THIS
MANUAL.
5. Keep this manual and all literature
safeguarded near or on the unit.
COMPRESSOR CYCLING
3 MINUTE MINIMUM OFF TIME
To prevent motor overheating
compressors must cycle off for a
minimum of 3 minutes.
5 MINUTE MINIMUM ON TIME
To maintain the proper oil level
compressors must cycle on for a
minimum of 5 minutes.
The cycle rate must not exceed 7
starts per hour.
WARNING

CL Series Feature String Nomenclature
Model Options
Feature Options
GEN
SIZE
VLT
INT PRT
A1
A2
A3
A4
B1
B2
B3
1A
1B
1C
1D
2
3
4
5A
5B
5C
6A
6B
6C
7
8
9
10
11
12
13
14A
14B
CL
-
125
-
3
-
0
-
B
E
0
4
-
0
0
0
:
0
0
0
0
-
0
0
0
-
0
0
0
-
0
0
0
-
J
A
F
0
0
B
H
-
0
0
-
0
0
0
A
0
0
B
0
B
15
16
17
18
19
20
21
22
23
11
CL Series Feature String Nomenclature
MODEL OPTIONS
Series and Generation
CL
Unit Size
045 = 45 Nominal Tons
060 = 60 Nominal Tons
070 = 70 Nominal Tons
075 = 75 Nominal Tons
095 = 95 Nominal Tons
100 = 100 Nominal Tons
110 = 110 Nominal Tons
125 = 125 Nominal Tons
134 = 134 Nominal Tons
135 = 135 Nominal Tons
155 = 155 Nominal Tons
170 = 170 Nominal Tons
190 = 190 Nominal Tons
210 = 210 Nominal Tons
230 = 230 Nominal Tons
Voltage
2 = 230V/3Φ/60Hz
3 = 460V/3Φ/60Hz
4 = 575V/3Φ/60Hz
8 = 208V/3Φ/60Hz
Interior Corrosion Protection
0 = Standard
A1: Cooling - Compressor Style
B = R-410A Dual Circuited Scroll Compressor
R = R-410A Independently Circuited Compressors
A2: Cooling - Condenser Style
A = Air-Cooled Condenser
E = Evaporative Condenser
A3: Cooling - Coating
0 = Standard
B = Polymer E-Coated (Condenser)
A4: Cooling - Staging
2 = 2 Stage
3 = 3 Stage
4 = 4 Stage
6 = 6 Stage
8 = 8 Stage
B1: Heating - Type
0 = No Heat
B2: Heating - Designation
0 = No Heat
B3: Heating - Staging
0 = No Heat
UNIT FEATURE OPTIONS
1A: Blank
0 = Standard
1B: Blank
0 = Standard
1C: Blank
0 = Standard
1D: Blank
0 = Standard
2: Blank
0 = Standard
3: Blank
0 = Standard
4: Blank
0 = Standard

CL Series Feature String Nomenclature
Model Options
Feature Options
GEN
SIZE
VLT
INT PRT
A1
A2
A3
A4
B1
B2
B3
1A
1B
1C
1D
2
3
4
5A
5B
5C
6A
6B
6C
7
8
9
10
11
12
13
14A
14B
CL
-
125
-
3
-
0
-
B
E
0
4
-
0
0
0
:
0
0
0
0
-
0
0
0
-
0
0
0
-
0
0
0
-
J
A
F
0
0
B
H
-
0
0
-
0
0
0
A
0
0
B
0
B
15
16
17
18
19
20
21
22
23
12
5A: Blank
0 = Standard
5B: Blank
0 = Standard
5C: Blank
0 = Standard
6A: Blank
0 = Standard
6B: Blank
0 = Standard
6C: Blank
0 = Standard
7: Refrigeration Control
0 = Standard
A = 5 Min Time Delay Relay Off
B = 20 Sec Time Delay Relay
C = 115V Outlet, Field Wired
D = 115V Outlet, Factory Wired
E = Options A + B
F = Options A + C
G = Options A + D
H = Options A + B + C
J = Options A + B + D
K = Options B + C
L = Options B + D
8: Refrigeration Options
0 = Standard
A = Hot Gas Bypass on Lead Stage
D = Hot Gas Bypass on Lead and Lag Stages
9: Refrigeration Accessories
0 = Standard
A = Sight Glass
B = Compressor Isolation Valves
C = Sight Glass + Compressor Isolation Valves
F = Compressor Isolation Valves + Condenser Fan
VFDs
G = Compressor Isolation Valves + Condenser Fan
VFDs + Sight Glass
10: Power Options
0 = Standard Single Point Power Block
A = Single Point Power Non-Fused Disconnect
(250A)
B = Single Point Power Non-Fused Disconnect
(400A)
C = Single Point Power Non-Fused Disconnect
(600A)
D = Single Point Power Non-Fused Disconnect
(800A)
E = Single Point Power Non-Fused Disconnect
(1200A)
11: Blank
0 = Standard
12: Controls
0 = Standard
B = Phase & Brown Out Protection
13: Special Controls
0 = Standard
D = VAV Unit Controller
E = Constant Volume Unit Controller
F = Make up Air Unit Controller
H = Field Installed DDC Controls by Others
J = Factory Installed DDC Controls by Others

CL Series Feature String Nomenclature
Model Options
Feature Options
GEN
SIZE
VLT
INT PRT
A1
A2
A3
A4
B1
B2
B3
1A
1B
1C
1D
2
3
4
5A
5B
5C
6A
6B
6C
7
8
9
10
11
12
13
14A
14B
CL
-
125
-
3
-
0
-
B
E
0
4
-
0
0
0
:
0
0
0
0
-
0
0
0
-
0
0
0
-
0
0
0
-
J
A
F
0
0
B
H
-
0
0
-
0
0
0
A
0
0
B
0
B
15
16
17
18
19
20
21
22
23
13
14A: Blank
0 = Standard
14B: Blank
0 = Standard
15: Blank
0 = Standard
16: Blank
0 = Standard
17: Blank
0 = Standard
18: Warranty
0 = Standard Warranty
A = Extended Compressor Warranty Years 2-5
19: Code Options
0 = Standard ETL USA Listing
A = M.E.A. (New York)
D = Chicago - Cool Only
H = ETL USA + Canada Listing
20: Blank
0 = Standard
21: Evaporative Condenser Option
0 = Standard, No Evaporative Condenser
A = Basic Package
B = Low Ambient Package
22: Blank
0 = Standard
23: Paint and Special Pricing Authorization
B = Standard Paint
U = Special Price Authorization and Special Paint
X = Special Price Authorization w/ Standard Paint

14
GENERAL DESCRIPTION
All AAON CL Series condensers are factory
assembled, wired, and shipped with a 100 psi
nitrogen holding charge. Models are available for
air-cooled and evaporative condenser
applications.
Unpacking:
When received, check unit for damage that might
have occurred in transit. If damage is found it
must be noted on the carrier’s Freight Bill. A
request for inspection by carrier’s agent must be
made in writing at once.
Also, check the unit nameplate to ensure the
correct model size and voltage have been received
to match the job requirements.
OWNER'S INFORMATION
Warning:
Failure to observe the following instructions will
result in premature failure of your system, and
possible voiding of the warranty.
Never cut off the main power supply to the unit,
except for complete shutdown. When power is cut
off from the unit, any compressors using
crankcase heaters cannot prevent refrigerant
migration. This means the compressor will cool
down, and liquid refrigerant may accumulate in
the compressor. Since the compressor is designed
to pump refrigerant gas, damage may occur when
power is restored.
Before unit operation, the main power switch
must be turned on for at least twenty four hours
for units with compressor crankcase heaters. This
will give the crankcase heater time to clear any
liquid accumulation out of the compressor before
it is required to run.
Always control the system from the thermostat, or
control panel, never at the main power supply
(except for emergency or for complete shutdown
of the system).
Improper installation, adjustment, alteration,
service, or maintenance can cause property
damage, personal injury or loss of life. Installation
and service must be performed by a qualified
installer, service agency or if gas fired units, the
gas supplier. Refer to installation instructions
provided with the unit and this manual.
The compressors must be on a minimum of
5 minutes and off for a minimum of 3 minutes.
The cycle rate must be no more than 7 starts per
hour.
The compressor life will be seriously shortened
by reduced lubrication, and the pumping of
excessive amounts of liquid oil and refrigerant.
QUALIFIED INSTALLER
Improper installation, adjustment,
alteration, service or maintenance can
cause property damage, personal injury or
loss of life. Startup and service must be
performed by a Factory Trained Service
Technician. A copy of this IOM must be
kept with the unit.
WARNING
Scroll compressors will be damaged by
operation with the wrong rotation. THE
SUCTION PRESSURE TRANSDUCER
HAS BEEN DISCONNECTED AFTER
TESTING AT THE FACTORY.
The wiring must be reconnected and
proper rotation determined at the time of
start-up by a qualified service technician
using suction and discharge pressure
gauges. Any alteration must be made at
the unit power connection.
WARNING

15
Wiring Diagrams:
A complete set of unit specific wiring diagrams in
both ladder and point-to-point form are laminated
in plastic and located inside the control
compartment door.
General Maintenance:
When the initial startup is made and on a periodic
schedule during operation, it is necessary to
perform routine service checks on the
performance of the condenser. This includes
reading and recording suction pressures and
checking for normal sub-cooling and superheat.
See the evaporative condenser and air-cooled
condenser sections in this manual for specific
details.
INSTALLATION
Lifting and Handling:
If cables or chains are used to hoist the unit they
must be the same length and care must be taken to
prevent damage to the cabinet.
Before lifting unit, be sure that all shipping
material has been removed from unit. If the unit
includes an evaporative condenser, make sure the
tank is empty before lifting. Secure hooks and
cables at all lifting points/lugs provided on the
unit.
Do not push, pull or lift the unit from anything
other than its base.
UNIT MUST BE RIGGED AT ALL
MARKED LIFTING POINTS (Typical)
Condenser Placement:
The AAON condenser is designed for outdoor
applications and mounting at ground level or on a
rooftop. It must be placed on a level and solid
foundation that has been prepared to support its
weight. When installed at ground level, a one-
piece concrete slab must be used with footings
that extend below the frost line.
With ground level installation, care must be taken
to protect the coil fins from damage due to
vandalism or other causes.
The placement relative to the building air intakes
and other structures must be carefully selected. Be
sure to observe the dimensions that are on the
rating plate of the condenser for operational and
service clearances, which will appear as follows:
Table 1 - Service Clearances
Location
Unit Size
045-135
134-230
Front - Vestibule Door Side
100"
142"
Back - Opposite of Front
100"
142"
Left Side - Condenser End
100"
100"
Right Side - Opposite of Left
100"
100"
Top
UNOBSTRUCTED
Condenser coils and fans must be free of any
obstructions in order to start and operate properly
with a correct amount of airflow.
For proper unit operation, the immediate area
around condenser must remain free of debris that
may be drawn in and obstruct airflow in the
condensing section.
Consideration must be given to obstruction caused
by snow accumulation when placing the unit.
Compressor Compartment Exhaust Fan:
Prior to unit operation the compressor
compartment exhaust fan shipping support
MUST BE removed from the exterior of the unit.
The exhaust fan also requires the installation of
the exterior rain hood provided with the unit.

16
Mounting Isolation:
For roof mounted applications or anytime
vibration transmission is a factor, vibration
isolators may be used.
Access Doors:
A lockable access door is provided to the
compressor and electrical compartment.
A light switch is on the wall of the compressor
control compartment.
Standard Evacuation Instructions:
Proper system evacuation is critical to remove
moisture and non-condensables from the system
before charging the system with refrigerant. Use
the following procedure to ensure the entire
system is pulled into a good vacuum.
1. System evacuation must be performed
anytime a system is open to atmospheric
pressure. The POE oils used with R-410A are
extremely hydroscopic in nature and
immediately begin pulling in moisture once
the system is opened to the atmosphere.
2. Before starting to evacuate the system, you
MUST ensure that there are no leaks by
pressurizing the system with 400 psig of dry
nitrogen and verifying no pressure loss after
one hour.
3. Four valve manifold gauge sets are more
effective than standard manifold gauge sets
due to the extra hose port in combination with
a 3/8’’ evacuation port. The larger diameter
evacuation port will expedite system
evacuation.
4. Connect the manifold set to the
condensing unit with one hose on the suction
line service valve, one hose on the liquid line
service valve and if an extra Schrader valve
is field installed on the suction line, connect
a third hose. Connect the vacuum pump to
the manifold set using a 3/8” vacuum rated
hose.
Figure 1 - CU evacuation connections
5. An accurate micron gauge must be used
and checked by pulling a vacuum on the
gauge by itself and verify a rapid drop to less
than 100 microns within a few minutes.
6. Do not attach the micron gauge to the
system until the gauge manifold is reading
28’’ of vacuum to ensure the micron gauge
does not see pressure and is thus damaged.
MICRON GAUGES WILL BE DAMAGED
BY PRESSURE!!!
7. It is a good practice to replace the vacuum
pump oil after one hour of the evacuation
process. The oil can be broken down in the
pump in the initial first hour causing system
evacuation to take longer than it should.
8. The minimum micron level required by
AAON is 350 microns for systems using POE
oils.
9. The system must then be isolated and the
pump turned off to check for vacuum rise due
to leaks or moisture in the system. The
micron gauge must not rise above
500 microns after 30 minutes of wait time.

17
Low Ambient & Modulating Reheat System
Evacuation Instructions:
Proper system evacuation is critical to remove
moisture and non-condensables from the system
before charging the system with refrigerant.
Systems with low ambient flooded condenser
option require the following procedure to ensure
the entire system is pulled into a good vacuum.
1. Perform system evacuation anytime a
system is open to atmospheric pressure. The
POE oils used with R-410A are extremely
hydroscopic in nature and immediately begin
pulling in moisture once the system is opened
to the atmosphere.
2. Open the reheat valve to 50% when
evacuating.
3. Before starting to evacuate the system, you
MUST ensure that there are no leaks by
pressurizing the system with 400 psig of dry
nitrogen and verifying no pressure loss after
one hour.
4. Four valve manifold gauge sets are more
effective than standard manifold gauge sets
due to the extra hose port in combination with
a 3/8’’ evacuation port. The larger diameter
evacuation port will expedite system
evacuation.
5. Connect the manifold set to the
condensing unit with one hose on the suction
line service valve, one hose on the liquid line
service valve, and a third hose on the reheat
line service valve. Connect the vacuum
pump to the manifold set using a 3/8” vacuum
rated hose. Figure 2 shows two circuits. The
first circuit has a reheat line, the second
circuit is just the suction and liquid line.
Figure 2 - CU evacuation connections
6. FAILURE to connect to the liquid line
service valve will result in the receiver tank
not being fully evacuated and most likely
lead to non-condensables in the system.
7. An accurate micron gauge must be used
and checked by pulling a vacuum on the
gauge by itself and verify a rapid drop to less
than 100 microns within a few minutes.
8. Do not attach the micron gauge to the
system until the gauge manifold is reading
28’’ of vacuum to ensure the micron gauge
does not see pressure and is thus damaged.
MICRON GAUGES WILL BE DAMAGED
BY PRESSURE!!!

18
9. Attach the micron gauge to the system on
the reheat line where it enters the air handler
unit. See Figure 3 below.
Figure 3 - AHU evacuation connections
10. It is a good practice to replace the vacuum
pump oil after one hour of the evacuation
process. The oil can be broken down in the
pump in the initial first hour causing system
evacuation to take longer than it should.
11. The minimum micron level required by
AAON is 350 microns for systems using POE
oils.
12. The system must then be isolated and the
pump turned off to check for vacuum rise due
to leaks or moisture in the system. The
micron gauge must not rise above
500 microns after 30 minutes of wait time.
Charging Refrigerant:
Charging a system in the field must be based on
determination of liquid sub-cooling and
evaporator superheat. On a system with a
thermostatic expansion valve liquid sub-cooling is
more representative of the charge than evaporator
superheat but both measurements must be taken.
Before Charging:
Refer to the Unit Nameplate to determine the
proper refrigerant to charge the system with.
The unit being charged must be at or near full load
conditions before adjusting the charge.
Units equipped with hot gas bypass must have the
hot gas bypass valve closed to get the proper
charge.
Units equipped with hot gas reheat must be
charged with the hot gas valve closed while the
unit is in cooling mode.
After adding or removing charge the system must
be allowed to stabilize, typically 10-15 minutes,
before making any other adjustments.
The type of unit and options determine the ranges
for liquid sub-cooling and evaporator superheat.
Refer to Table 2when determining the proper sub-
cooling.
The vertical rise of the liquid line must be known
in order to adjust the sub-cooling range for proper
charge.
Units equipped with low ambient (0°F) option see
special charging instructions at the end of the
charging instructions.
CLEAN AIR ACT
The Clean Air Act of 1990 bans the
intentional venting of refrigerant as of July
1, 1992. Approved methods of recovery,
recycling, or reclaiming must be followed.
WARNING
Reheat Line on the
Outside of the Air
Handler

19
Checking Liquid Sub-cooling:
1. Measure the temperature of the liquid line
as it leaves the condenser coil.
2. Read the gauge pressure reading of the
liquid line close to the point where the
temperature was taken. You must use liquid
line pressure as it will vary from discharge
pressure due to condenser coil pressure drop.
3. Convert the pressure obtained in Step 2 to
a saturated temperature using the appropriate
refrigerant temperature-pressure chart.
4. Subtract the measured liquid line
temperature in Step 1 from the saturated
temperature in Step 3 to determine the liquid
sub-cooling.
5. Compare calculated sub-cooling to Table
2for the appropriate unit type and options.
Checking Evaporator Superheat:
1. Measure the temperature of the suction
line close to the evaporator.
2. Read gauge pressure at the suction line
close to the evaporator.
3. Convert the pressure obtained in Step 2 to
a saturated temperature using the appropriate
refrigerant temperature-pressure chart.
4. Subtract the saturated temperature in
Step 3 from the measured suction line
temperature in Step 1 to determine the
evaporator superheat.
5. Compare calculated superheat to Table 2
for the appropriate unit type and options.
Table 2 - Acceptable Refrigerant Circuit Values
Sub-
cooling
(°F)
Superheat
(°F)
Sub-cooling
W/Hot Gas
Reheat (°F)
Air Cooled
Condenser
8-15*
8-15**
5-15*
Evaporative
Cooled
Condenser
6-10*
8-15**
8-12*
Water
Cooled
Condenser
6-10*
8-15**
8-12*
* Sub-cooling must be increased by 1°F per
10 feet of vertical liquid line rise for R-410A
** Superheat will increase with long suction line
runs.
The system is undercharged if:
1. The superheat is too high and
2. The sub-cooling is too low
Correct an undercharged system by adding
refrigerant to the system to reduce superheat and
raise sub-cooling.
If the sub-cooling is correct and the superheat is
too high, the TXV may need adjustment to correct
the superheat.
Refrigerant overcharging leads to excess
refrigerant in condenser coils resulting in
elevated compressor discharge pressure.
DO NOT OVERCHARGE!
CAUTION

20
Special Low Ambient Charging Instructions:
For units equipped with low ambient refrigerant
flood back option being charged in the summer
when the ambient temperature is warm:
If the ambient is above 70°F, charge to
approximately 1-2°F of sub-cooling measured at
the inlet to the expansion valve. Once enough
charge has been added to get the evaporator
superheat and sub-cooling values to the correct
setting more charge must be added. Add the
calculated charge amount to flood the condenser
coil. The additional charge is required for the
system when running in cold ambient conditions.
Contact Technical Support for this charge amount.
AAON Technical Support
Ph: [phone]
[email protected]
For units equipped with low ambient refrigerant
flood back option being charged in the winter
when the ambient temperature is cold:
1. If the ambient is below 70°F, charge to
approximately 1-2°F of sub-cooling
measured at the inlet to the expansion valve.
Once enough charge has been added to get
the evaporator superheat and sub-cooling
values to the correct setting, more charge may
need to be added. If the ambient temperature
is 0°F, no more charge is required. If the
ambient temperature is between 0°F and
70°F, multiply the charge amount needed at
70°F ambient (call AAON Technical Support
to get this value) by the percentage below that
corresponds to the ambient temperature. The
result is the additional charge that must be
added to the circuit.
Table 3 - % Charge to Flood Condenser Coil for
Ambient Below 70°F
Condenser
Ambient
Temperature °F
% of flooded charge
needed at 70°F
ambient
60
60%
50
37%
40
24%
30
15%
20
8%
0
0%
2. Check the unit for proper operation once
the ambient temperature is above 80°F.
Low Ambient Operation:
The AAON low ambient (condenser flood-back)
system is used to operate a refrigerant system
below 35°F outside air temperature. As the
ambient temperature drops, the condenser
becomes more effective therefore lowering the
head pressure. When the head pressure gets too
low, there will be insufficient pressure to operate
the expansion valve properly. During low
ambient temperatures, it is difficult to start a
system because the refrigerant will migrate to the
cold part of the system (condenser) and make it
difficult for refrigerant to flow.
The AAON low ambient system maintains normal
head pressure during periods of low ambient by
restricting liquid flow from the condenser to the
receiver, and at the same time bypassing hot gas
around the condenser to the inlet of the receiver.
This backs liquid refrigerant up into the condenser
reducing its capacity that in turn increases the
condensing pressure. At the same time the
bypassed hot gas raises liquid pressure in the
receiver, allowing the system to operate properly.
There are different types of low ambient control
used. The following describe the different
systems. Inspect the unit to determine the system
used.