Page 1
Installation and Maintenance Manual IM-802
Group: Unitary
Part Number: IM-802
Date: August 2005
Supersedes: March 2005
ACU Split System Air Conditioners
7-1/2 & 10 TON
© 2004 McQuay International
IM-802 Page 1
Page 2
Table of Contents
MODEL NOMENCLATURE . . . . . . . . . . . . . . . . . . . . 3
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
GENERAL WARNINGS . . . . . . . . . . . . . . . . . . . . . . . 5
PRODUCT DESCRIPTION . . . . . . . . . . . . . . . . . . . . 6
DUCTWORK CONSIDERATIONS . . . . . . . . . . . . . . . 6
SITE SELECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
TYPICAL INSTALLATION . . . . . . . . . . . . . . . . . . . . . 7
RIGGING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
UNIT CORNER WEIGHT . . . . . . . . . . . . . . . . . . . . . . 7
REFRIGERANT TUBING . . . . . . . . . . . . . . . . . . . . . . 7
ELECTRICAL WIRING . . . . . . . . . . . . . . . . . . . . . . . 9
SYSTEM EVACUATION AND CHARGING . . . . . . 10
SYSTEM EVACUATION . . . . . . . . . . . . . . . . . . . . . 11
PRELIMINARY CHARGE ADJUSTMENT . . . . . . . . 12
FINAL CHARGE ADJUSTMENT . . . . . . . . . . . . . . . 12
EXPANSION VALVE INDOOR COILS . . . . . . . . . . 12
TROUBLE SHOOTING . . . . . . . . . . . . . . . . . . . . . . 13
WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . 14
"McQuay" is a registered trademark of McQuay International.
© 2004 McQuay International
"Illustrations and information cover the McQuay International products at the time of publication and we reserve the right to make changes in
Page 2 IM-802
design and construction at any time without notice."
Page 3
MODEL NOMENCLATURE
M
A
N
0
1
0
A
odel
CU = Air Cooled Cooling Unit
ominal Capacity (tons)
90 = 7-1/2
20 = 10
Table 1: Unit Nameplate Model Number Identifier
Unit Nameplate McQuay Model Number
CKL090-3L ACU090APEY
CKL090-4L ACU090AQEY
CKL120-3L ACU120APEY
CKL120-4L ACU120AQEY
ACU 090
PEY
Future Use
EER
E = 10.3
Voltage/Phase
P = 208-230/3/6
Q = 460/3/60
Vintage
IM-802 Page 3
Page 4
INTRODUCTION
General Description
These installation instructions cover the outdoor installation of
cooling only condensing units from 7½ to 10 tons. See the
product catalog applicable to your model for information
regarding specifications applicable to your model and accessories.
Receiving Inspection
McQuay products are carefully inspected prior to shipment
and the carrier has assumed responsibility for loss or damage
upon acceptance of the shipment.
Upon receiving your shipment, check all items carefully
against the Bill of Lading. Inspect the unit and/or accessories
for shipping damage as soon as they are received. Immediately file claims for loss or damage, either shipping or concealed, with the shipping company.
Check the unit nameplate to verify the model number and electrical characteristics are correct. In the event an incorrect unit
is shipped, it must be returned to the supplier and must NOT
be installed. The manufacturer disclaims all responsibility for
the installation of incorrectly shipped units.
Codes and Regulations
This product is designed and manufactured to permit installation in accordance with National Codes. System design
should, where applicable, follow information presented in
accepted industry guides such as the ASHRAE Handbooks. It
is the installer' s responsibility to install the product in accordance with National Codes and/or prevailing local codes and
regulations. The manufacturer disclaims all responsibility for
equipment installed in violation of any code or regulations.
IMPORTANT
The United States Environmental Protection Agency
(EPA) regulations cover introduction and disposal of
refrigerants in this unit. Failure to follow those
regulations can harm the environment and lead to
substantial fines. Because regulations can change, a
certified technician should perform any work done on
this unit. If you have any questions, please contact the
local office of the EPA.
Important Message to the Installer
This equipment is to be installed by an experienced installation
company and fully trained personnel. Carefully read all
instructions and take into account any special considerations
prior to installing the unit. Give this manual to the owner and
explain its provisions.
Important Message to the Owner
Read these instructions carefully and keep them near the product for future reference. Although these instructions are
addressed primarily to the installer, useful maintenance information is included. Have the installer acquaint you with the
operation of the product and periodic maintenance requirements.
Recognize Safety Symbols, Words, and Labels
The following symbols and labels are used throughout this
manual to indicate immediate or potential hazards. It is the
owner's and installer's responsibility to read and comply with
all safety information and instructions accompanying these
symbols. Failure to heed safety information increases the risk
of property damage and/or product damage, serious personal
injury or death. Improper installation, operation and mainte-
nance can void the warranty.
DANGER
Immediate hazards which WILL result in property
damage, product damage, severe personal injury and/
or death.
WARNING
Hazards or unsafe practice CAN result in property
damage, product damage, sever personal injury and/or
death.
CAUTION
Hazards or unsafe practices which CAN result in
property damage, product damage, and/or personal
injury.
Replacement Parts
Replacement parts can be obtained by contacting McQuay at
1
-800-37-PARTS. When contacting McQuay for service or
replacement parts, refer to the model number and serial number of the unit as stamped on the nameplate attached to the
unit.
Page 4 IM-802
Page 5
GENERAL WARNINGS
WARNING
Before servicing or installing the electrical power must
be in OFF. More than one disconnect may exist.
Failure to disconnect all power can cause electrical
shock, serious personal injury or death.
WARNING
The unit must have an uninterrupted, unbroken
electrical ground. Failure to properly ground can cause
severe personal injury or death.
WARNING
Installation and service by trained, qualified technicians
only. High pressure and electricity can cause severe
personal injury or death. Observe ALL warnings
contained in this manual and the labels/tags attached to
the equipment.
WARNING
When installing or servicing, wear protective gloves,
gear and eyeware. Also observe special safety
requirements (hard hats etc.).
CCAUTION
To protect the unit when welding close to the painted
surfaces, use a quenching cloth to prevent scorching or
marring of equipment finish.
CCAUTION
Read these instructions before performing this
installation or servicing this unit. All installations must
be in accordance with all national, state, or local
building codes.
IM-802 Page 5
Page 6
PRODUCT DESCRIPTION
When matched with the appropriate air handler(s) or evaporator coil(s) the ACU090/120 condenser complies with the rminimum efficiency equirements found in ASHRAE 90.1-1999.
See the product catalog for the indoor model selection recommendation.
Units are intended for use with a single stage room thermostat. This thermostat is not supplied with this equipment. Only
thermostats that use 24 VAC control circuitry are to be used.
Table 2: Physical Data
Net Weight (Lbs.) 345 395
Shipping Weight (Lbs.) 370 420
Refrigerant R-22
Compressor Type Scroll
Quantity 1
Oil Charge Initial/Recharge 85/81 110/106
Condenser Fan Type Propeller
Fan Diameter (in) 26
Fan Motor Type Direct Drive PCS
Fan Motor (HP) 1
Fan Motor (RPM) 1100
Nominal Cond. Airflow (CFM) 6600
Condenser Coil Material Riffled Copper Tubes / Al Fins
2
Face Area (Ft
Refrigerant Connections Sweat Type
Suction Line Connection (in) 1-3/8
Liquid Line Connection (in) 5/8
High Pressure Control (PSIG) 425 Cut-out / Manual Reset
Low Pressure Control (PSIG) 7 Cut-out / 25 Cut-in
)
ACU090 ACU120
30
DUCTWORK CONSIDERATIONS
For proper performance, size the indoor ductwork to accommodate 375-425 CFM per ton of cooling with a static pressure
not to exceed 0.5" WC. Inadequate ductwork that restricts airflow can result in improper cooling performance and compressor failure.
SITE SELECTION
This unit is designed for outdoor installations only.
Air Supply
Units are air-cooled condensers. For optimum unit performance, the installation site should provide unobstructed airflow. See the following figure for minimum clearances from
other air-cooled condensers and obstructions such as walls or
overhangs.
Note: Also consider adequate service clearances.
Figure 1. Recommended Clearances
60"
24"
12"
12"12"
Refrigerant System Requirements
The selected site should be no greater than 50’ below or 70’
above the evaporator section. For optimum performance, use
the minimum length of interconnecting tubing. Where possible, minimize bends and turns
Wiring and Tubing Protection
Protect electrical wiring and refrigerant tubing from damage
due to incidental contact, such as being walked upon.
Vibration and Sound Control
Units are engineered to produce the minimum sound and
vibration. To minimize sound or vibration issues, securely
mount the unit to a surface that is:
•Solid
• Greatest practical mass
• Ridged
• Minimum radiating surface
Where possible, the slab for a ground level unit should not be
connected to the wall or the building.
Prohibited Locations
Do not locate this unit in the following locations:
• Inside a building
• Directly under a vent termination from a gas appliance
• Within 3 feet of a clothes drier vent
• Where water may rise into the unit
Page 6 IM-802
Page 7
TYPICAL INSTALLATION
Typical locations for the unit are slab mounted and roof
mounted. For unit weight data, see the "Product Description"
section of this manual.
Slab Mounting
The slab must be capable of supporting the weight of the unit.
The slab should be a minimum of 6" wider than the unit in all
directions. If required, the slab should be elevated to help
avoid water damage due to flooding. Before installing the unit
onto a slab, the wooden shipping skid must be removed.
UNIT CORNER WEIGHT
The following figure and table is to be used for determining
the unit corner weight. The unit net weight and shipping
weight is provided in the “Product Description” section of this
manual.
Figure 3.
35.5"
D
C
Roof Mounting
Carefully consider the load carrying capability of the roof. If
possible, locate the unit where walls or partitions can offer
additional support. If doubt exists regarding the integrity of
the roof or its supporting structure, consult a structural engineer.
RIGGING
WARNING
All panels must be in position and secured before lifting
this equipment. Dislodged panels can cause equipment
damage, severe personal injury or death.
Figure 2. Rigging Unit for Lifting
41.5"
A
Table 3:
35.5"
B
Corner ACU090 ACU120
A 90 Lbs. 105 Lbs.
B 90 Lbs. 105 Lbs.
C 75 Lbs. 80 Lbs.
D 90 Lbs. 105 Lbs.
REFRIGERANT TUBING
CAUTION
Wrap service valves with a wet rag or similar approved
thermal heat trap around the valve to avoid damage
due to overheating.
WARNING
Wear protective clothing and eye protection when
making any welded connection.
Preparing the Tubing
Ends must be cut round and burr free and cleaned. Failure to
follow this practice can result in refrigerant leaks.
Post Brazing
Quench all welded joints with water or a wet rag.
Piping Size
Using a carefully estimated length of refrigerant tubing (distance between condenser and evaporator), apply the following
When lifting the unit, use spreader bars (field supplied) to help
avoid damage from lifting cables/straps. Also, to help avoid
damage to the cabinet louvers, use protective material (i.e. plywood) behind the cables/straps.
Arrange the straps to form a central suspension point (see Figure 2). When raising and setting the unit, observe all safety
rules. When the unit is in position, the wooden shipping skid
table to determine the tubing diameter:
Table 4: Tubing Diameter
Model
ACU090 5/8 1-1/8 5/8 1-3/8 5/8 1-3/8 5/8 1-3/8
ACU120 5/8 1-1/8 5/8 1-5/8 5/8 1-5/8 5/8 1-5/8
0"-24’ 25’-49’ 50’-74’ 75’-99’
LSLSLSLS
Outside Diameter Line Size (in)
and all lifting materials must be removed.
IM-802 Page 7
Page 8
Suction Line Insulation
Install all suction lines with a recognized tubing insulation that
is a minimum of 3/8" thick.
Hangers and Isolation
Insolate all refrigerant lines from the structure and support
with hangers. See Figure 4 for details.
Figure 4. Hangers and Isolation
Inverted Suction Line Loop
When the condenser is located at the same level or above the
evaporator section, employ an inverted loop on the suction
line. This practice will prevent liquid refrigerant from migrating into the compressor during shutdown. See Figure 5.
Figure 5. Inverted Loop
INVERTED LOOP
LIQUID LINE
CONDENSING UNIT
EVAPORATOR BLOWER
SUCTION LINE
8'
50' MAX
Oil Return
To facilitate oil return to the compressor, pitch a horizontal
suction line (1/2" per 10’) toward the condensing unit. See Figure 6.
Figure 6. Suction Line Pitch
CONDENSING UNIT
PITCH SUCTION LINE TOWARD OUTDOOR
UNIT 1/2" FOR EVERY 10' OF LINE
EVAPORATOR BLOWER
Condenser Above the Evaporator
When the condenser is located 4’ or greater above the evaporator section, install a suction line oil trap at the base of the riser.
Add an additional oil trap for each 20’ of vertical riser. See
Figure 7.
Figure 7. Suction Line Oil Trap
CONDENSING UNIT
ADDITIONAL SUCTION LINE OIL
70' MAX
LIQUID LINE
SUCTION LINE OIL TRAPS WHEN INDOOR UNIT
IS 4 FEET OR MORE BELOW OUTDOOR UNIT
TRAP FOR EACH 20' RISE OF PIPE
EVAPORATOR BLOWER
Filter Drier and Sight Glass
A liquid line filter drier is factory installed. A sight glass/
moisture indicator is provided with the unit. This is to be field
installed on the liquid line as close as practical to the service
valve.
Holding Charge
Units are factory shipped with a 2 lb. R-22 holding charge.
When welding, introduce an inert gas (i.e. nitrogen) through
the tubing to prevent the formation of copper oxide inside the
tubing.
TXV
For improved refrigerant management, equip the evaporator
coil with a thermal expansion valve (TXV).
Liquid Line Solenoid
A field supplied liquid line solenoid should be added to the liquid line as close as possible to the evaporator coil. Wire the
solenoid to close when the compressor stops to prevent refrigerant migration in the “OFF” cycle.
Evacuation and Charging
See the “Evacuation and Charging” section of this manual for
instructions.
LIQUID LINE
Page 8 IM-802
Page 9
ELECTRICAL WIRING
WARNING
Before servicing or installing this equipment, the
electrical power to this unit must be in the “OFF”
position. More than one disconnect may exist. Failure
to observe this warning may result in an electrical shock
that can cause personal injury.
WARNING
The unit must have an uninterrupted, unbroken electrical
ground. Failure to properly ground can cause severe
personal injury or death.
The unit must have an uninterrupted, unbroken electrical ground.
The electrical ground circuit may consist of an appropriately
sized electrical wire connecting the ground lug in the unit control box wire to the building electrical service panel. Other
methods of grounding are permitted if performed in accordance with the National Electric Code (NEC)/American
National Standards Institute (ANSI)/National Fire Protection
Association (NFPA) 70 and local/state codes. In Canada, electrical grounding is to be in accordance with the Canadian Electric Code CSA C22.1. Failure to observe this warning can
result in electrical shock that can cause serious personal injury
or death.
CAUTION
To avoid risk of fire or equipment damage, use only
copper conductors.
Inspection of the Building Electrical Service
This unit is designed for 3-phase operation. DO NOT OPERATE ON A SINGLE PHASE POWER SUPPLY. Measure the
power supply to the unit. The supply voltage must be in agreement with the unit nameplate power requirements and within
the range shown below:
Table 5: Supply Voltage Range
Model Voltage
ACU090 208/230 187 253
ACU090 460 414 506
ACU120 208/230 187 253
ACU120 460 414 506
Minimum Supply
Voltage
Maximum Supply
Voltage
Voltage Balance
The supply voltage shall be unbalance (phase to phase) within
2%. To calculate the percentage of voltage unbalance use the
following formula:
Percentage
Voltage = 100 x
Unbalance
Max. Voltage Devation From Avg.Voltage
Avg. Voltage
Example
L1 - L2 = 220V
L2 - L3 = 216V
L1 - L3 = 213V
Avg. Voltage =(220 + 216 + 213) / 3
=649 / 3
=216
Max. Deviation from Avg. =220 - 216 = 4
% Voltage Unbalance = 100 x (4 / 216)
= 400 / 216
= 1.8%
Determine Wire Size
The selection of the appropriate supply wire size is important
to the operation of the equipment. When selecting the wire
size, the following are important elements of the decision:
• The wire size is sufficient to carry the Minimum Circuit Ampacity (MCA). The unit MCA can be found on the equipment nameplate and the following table.
Table 6: Minimum Circuit Ampacity
• The wire is appropriately sized to allow for no more than a 2%
• Refer to the latest edition of the National Electric Code or, in
Table 7: Maximum Allowable length in Feet to Limit Voltage
drop to 2%*
Model Voltage MCA
ACU090 208/230 37.8
ACU090 460 18.8
ACU120 208/230 43.3
ACU120 460 22.2
voltage drop from the building breaker/fuse panel to the unit.
Canada, the Canadian Electric Code when determining the correct wire size. The following table shows the current carrying
o
capabilities for copper conductors rated at 75
C with a 2% volt-
age drop.
Wire Size
(AWG)
14 75 50 37 NR NR NR NR NR
12 118 79 59 47 NR NR NR NR
10 188 125 95 75 63 54 NR NR
8 301 201 150 120 100 86 75 68
6 471 314 235 188 157 134 118 110
10 15 20 25 30 35 40 45
Min. Circuit Ampacity (MCA)
*Based on NEC 1996
IM-802 Page 9
Page 10
Example
A 208/230 volt ACU120 is to be installed. The distance
from the building breaker box to the unit is 75’. Calculate
the minimum wire size assuming no more than 2% voltage
drop.
MCA = 43.3 (from nameplate and table).
Applying previous table wire sizes less than #8 AWG cannot be used for circuits which have a rating of 45A. The #8
wire is not suitable because the maximum length for a 45A
circuit is 68’. Solution: a #6 AWG wire is suitable up to 110’.
Note: It is the contractor’s responsibility to follow the NEC
(USA) or CEC (Canada) when sizing the service wire for
this unit.
Service Disconnect Box
A service disconnect box is required as per NEC.
Fuse – HACR Breakers
Protection provided by either fuses or HACR type breakers.
Refer to the unit nameplate and the following table for the
maximum overcurrent protection permitted.
Table 8: Maximum Overcurrent Protection
Model Voltage *Max. Fuse
ACU090 208/230 60
ACU090 460 30
ACU120 208/230 60
ACU120 460 35
* Fuse or HACR Breaker of same value.
Line Voltage Wiring
Run all line voltage wiring through conduit from the service
disconnect box to the unit. Refer to the NEC (in Canada,
CEC) for the correct size conduit based on the wire size. The
conduit must enter the control box through the hole provided
in the bottom. Note: hole is sized for ¾” conduit. If permitted
by code, flexible conduit is preferred to minimize vibration
transmission from the unit to the building.
Connect the line voltage wires to the L1, L2, and L3 terminals
of the definite purpose contactor (located in the unit control
box). Refer to the wiring diagram attached to the unit when
making these connections. The unit wiring diagram is also
included at the end of this manual.
The unit must be grounded. The electrical ground circuit must
consist of an appropriately sized electrical wire connecting to
the ground lug in the unit control box and wired to the building
electrical service panel. Other methods of grounding are permitted if performed in accordance with the National Electric
Code (NEC)/American National Standards Institute (ANSI)/
National Fire Protection Association (NFPA) 70 and local/state
codes. In Canada, electrical grounding must be in accordance
with the Canadian Electric Code CSA C22.1.
Low Voltage Connections
Units require a 2-conductor low voltage circuit from the room
thermostat. The wires must be no smaller than 18 AWG. The
field connection for this circuit is to be made in the unit control
box using solderless connectors such as wire nuts. See Figure
8 for a typical low voltage hook-up.
Figure 8. Single State Low Voltage Hook-up
THERMOSTAT CHT18-60
Y1 RW1G
AIR
HANDLER
SAH090/120
CONDENSING
UNIT
ACU090/120
YELLOW
BROWN
RED
WHITE
BLUEBLUE
Control Box Components
See Figure 9 for the location of the electrical components.
Figure 9. Elecrical Component Locations
CONTACTOR
HIGH VOLTAGE
CONNECTIONS
HIGH VOLTAGE
ENTRANCE
CAPACITOR
GROUND LUG
LOW VOLTAGE
CONNECTIONS
LOW VOLTAGE
ENTRANCE
SYSTEM EVACUATION AND
CHARGING
WARNING
To avoid possible explosion, death, or injury, practice
safe handling of refrigerants.
WARNING
Refrigerants are heavier than air. They can “push out”
the oxygen in your lungs or in any enclosed space. To
avoid difficulty in breathing or death.
• Never sniff refrigerant.
• Never purge refrigerant.
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Page 11
WARNING
If an indoor refrigerant leak is suspected, thoroughly
ventilate the area before beginning work.
WARNING
Liquid refrigerant can be very cold. To avoid possible
frostbite or blindness, avoid contact and wear protective
gloves and eyeware. If liquid refrigerant does contact
your skin or eyes, seek medical help immediately.
Always follow EPA regulations. Never burn refrigerant
as poisonous gas will be produced.
WARNING
To avoid possible explosion, use refrigerant cylinders
properly:
If you must heat a cylinder for faster charging, partly
immerse it in warm water. Never apply flame or steam
to the cylinder.
Store cylinders in a cool, dry place. Never use a
cylinder as a platform or a roller.
Never add anything other than R-22 to an R-22
cylinder.
Never fill a cylinder more than 80% full of liquid
refrigerant.
When removing refrigerant from a system, use only
returnable (not disposable) service cylinders. Check the
cylinder for its pressure rating and hydrostatic test date.
Check the cylinder for any damage, that may lead to a
leak or explosion. If in doubt, do not use the cylinder.
Leak Test
WARNING
To avoid the risk of fire or explosion, never use oxygen,
high pressure or flammable gas for leak testing of a
refrigeration system.
1. Verify that both hand valves on the gauge manifold are
closed relative to the center port (i.e., turned in all the
way). Attach this gauge manifold to the service valves on
the unit.
WARNING
To avoid possible explosion, the line from the nitrogen
cylinder must include a pressure regulator and a
pressure relief valve. The pressure relief valve must be
set to open at no more than 150 psig.
2. Connect a cylinder of dry nitrogen to the center port on
the gauge manifold.
3. Open the hand valve a minimal amount on the line coming from the nitrogen cylinder.
4. Open the high pressure valve on the gauge manifold.
Pressurize the refrigerant lines and the indoor coil to 150
psig (1034 kPA).
WARNING
To avoid possible explosion or equipment damage, do
not exceed 150 psig when pressure testing.
After you reach 150 psig, close the valve on the nitrogen cylinder. Disconnect it from the gauge manifold. If you plan to use
an electronic leak detector, add a trace of R-22 to the system (if
permitted by current EPA regulations).
5. Apply a soap solution on all connections and joints. If you
see bubbles, you have a leak. Mark these locations.
6. Use the gauge manifold to carefully release the nitrogen
from the system. If leaks were found, repair them. After
repair, repeat the above pressure test. If no leaks exist,
proceed to system evacuation.
SYSTEM EVACUATION
1. Connect the vacuum pump, high vacuum manifold set
with high vacuum hoses, thermocouple vacuum gauge
and charging cylinder as shown in Figure 10. Begin with
all valves fully closed.
2. If service fill valves are used for evacuation, use a core
remover to lift the valve core. It provides greater efficiency.
3. Confirm proper pump and gauge operation. Open the
shutoff valve that leads to the high vacuum gauge manifold. Start the pump. When the compound gauge (low
side) reading drops approximately 29 inches of vacuum,
open the valve to the thermocouple vacuum gauge and
evacuate until the gauge reads 250 microns or less.
4. Close the valve to the thermocouple vacuum gauge. This
avoids potential gauge damage from “pegging the meter”.
5. Open the high and low side valves on the gauge manifold.
Keeping the valve on the charging cylinder closed, open the
valve on the gauge manifold that leads to the cylinder.
6. Evacuate the system to about 29 inches Hg as measured by
the compound (low side) gauge.
7. Open the valve to the thermocouple vacuum gauge. Evacu-
ate until the gauge reads 250 microns or less.
8. Close the valve to the vacuum pump. Wait five minutes,
then check the pressure on the thermocouple vacuum
gauge:
• If the pressure is not more than 1500 microns, the system is
leak-free and properly evacuated. Proceed to Step 9.
• If the pressure rises, but holds at about 5000 microns, moisture and non-condensibles are still present. Open the valve
to the vacuum pump, and go back to Step 7.
• If the pressure rises above 5000 microns, a leak is present.
Go back to “Leak Testing” section above
9. Close the valve to the thermocouple vacuum gauge. Close
the valve to the vacuum pump. Shut off the pump.
IM-802 Page 11
Page 12
Figure 10. System Evacuation Components
THERMOCOUPLE
VACUUM
GAUGE
DIAL-A-CHARGE
TO
RELATED
GAUGE
PORTS OF
COND. UNIT
LARGE DIAMETER
BRAIDED VACUUM
A. LOW S IDE VALV E
B. HIGH SIDE VA LVE
C. VACUUM PUMP
D. THERMOCOUPLE GAUGE
E. MANIFOLD GAUGE
F. CHAR GING CYLI NDER
HIGH VACUUM
MANIFOLD
HOSES
CHARGING CYLINDER
LOW SIDE
GAUGE
HIGH VACUUM PUMP
A
HIGH SIDE
GAUGE
D
B
C
E
F
PRELIMINARY CHARGE
ADJUSTMENT
CAUTION
See the wiring diagram or outdoor unit specification
sheet to determine if this unit has a crankcase heater. If
it does, you must connect electrical power to the unit for
four hours before operating the compressor. Failure to
do so can result in compressor damage.
CAUTION
During all installation and service work, follow all
regulations of the Environmental Protection Agency.
(This system uses R-22 - an HCFC [Hydrogenated
Chlorofluorocarbon].) Violation of EPA regulations can
cause environmental damage and result in fines or
other penalties.
Use a male hex head wrench (5/16" for liquid) to carefully
open the liquid valve stem on the unit. Use a service wrench
or crescent wrench to open the suction ball valve. The valve is
fully open with a 90-degree turn (i.e. the stem is inline with the
valve flow direction).
The outdoor unit is factory charged with 2 lb. R-22.
CAUTION
Use only refrigerant that is certified to meet ARI
Standard 700. Used refrigerant can cause compressor
damage and will void the warranty. Most portable
machines cannot clean used refrigerant well enough to
meet this ARI Standard.
CAUTION
When adding additional refrigerant to a system, add
only refrigerant vapor (not liquid) through the suction
valve (low side) on the outdoor unit. Any other practice
can cause compressor damage.
FINAL CHARGE ADJUSTMENT
CAUTION
Never operate the compressor with the suction valve
closed to “test the compressor pumping efficiency”. In
some cases, this can cause serious compressor
damage.
For 25’ of line set, the 7-1/2 ton charge is approximately 17 lb.
For 25’ of line set, the 10 ton is approximately 20 lb. of R-22.
Do not start with these amounts.
For installation greater than 25’ of line set, indoor unit airflow,
condensing unit location and number of tubing fittings will
have an impact on final unit charge amount. Start with half of
the 25’ line set charge and proceed.
Turn the electrical power on, and let the system run. Wait for
the refrigerant pressures to stabilize.
EXPANSION VALVE INDOOR COILS
NOTE: EXPANSION VALVE BULB; Must be in place on
suction line and insulated.
NOTE: EXPANSION VALVE INDOORS; At stabilized
cooling conditions and with an outdoor temperature
of 60°F or higher, the system should have from 9°F
to 13°F subcooling. For a proper subcooling reading, measure the refrigerant pressure and temperature at the outdoor unit’s liquid line service valve. If
you have less than 9°F subcooling, add charge. If
you have more than 13°F subcooling, remove
charge.
While reaching the proper subcooling level, it is important to
know the discharge line temperature. This temperature should
be at least 80°F over ambient or the unit is flooding back to the
compressor. If flooding (i.e. low discharge line temperature)
occurs, adjust the valve stem on the expansion valve inward
(clockwise viewing the end of the expansion valve). This will
increase the super heat.
After achieving the proper subcooling and a sufficient discharge temperature, make small adjustments to the expansion
valve stem to reach 8°F to 10°F of superheat. Adjusting the
valve stem in (clockwise) increases superheat. Adjusting the
valve stem out (counter clockwise) decreases superheat. If the
system is performing properly, re-install the service port caps
and the valve bonnets. With the valve opened, the valve bonnet is the primary seal against refrigerant leaks. Apply two
drops of clean oil to the cap threads, allowing the oil to run
down to the inner cap seal surface. Close the caps finger-tight.
Then tighten an additional two to three hex flats.
NOTE: Subsequent opening and replacing of the cap will
require only 1/2 to 1 hex flat. See the table below for
the torque required for an effective seal on the valve
bonnet (1/6 turn past finger tight).
Table 9: Valve Bonnet Torqure
Tubing Size Torque (Foot-Pounds)
5/8 14
1 3/8 16
After closing the valve bonnet, perform a final refrigerant leak
test on the valves and sweat connections. Return the room
thermostat to the desired settings.
Page 12 IM-802
Page 13
TROUBLE SHOOTING
IMPORTANT
Qualified installer/servicer only
When troubleshooting, the first step should always be
to check for clean coils, clean filter(s) and proper
airflow. Indoor airflow should be 375 to 425 CFM per
ton of cooling based on the size of the outdoor unit. The
most common way of establishing indoor airflow is
heating temperature rise. Indoor airflow will then be
(Heating output of equipment) / (1.1 x temp. rise). In
The ACU90/120 condenser is equipped with a 3-phase
scroll compressor. Improper phase rotation can
damage equipment.
If the unit sounds noisy and/or the suction and liquid pressures
are almost equal, the compressor is operating in the reverse
rotation. Reverse the two (2) incoming power supply leads.
other cases, measurement of external static pressure is
helpful. For details, see the Installation Instructions for
your indoor equipment.
Table 10: Trouble Shooting Analysis
COMPLANT PROBABLE CAUSE REMEDY
1. Purge or pump-down excessive charge.
2. Make certain that coil is not fouled in any way, or that air is not re-circulating.
3. Purge these gases from the system. Recharge system, if necessary.
1. Charge system until sight glass is clear of bubbles.
2. Replace compressor.
1. Open the liquid line valve.
2. Replace filter-dryer.
3. Detach the bulb from the suction line and hold in one hand. If no liquid refrigerant goes through the valve, replace the valve.
4. Test the unit for leaks. Add refrigerant until sight glass is free from bubbles,
after repairing leak.
5. Clean or replace filter.
6. Defrost and clean coil. Clean or replace filters.
7. Excessive liquid line drop. Check liquid line size.
8. Increase the blower speed.
1. Correct valve action or replace the valve.
2. Fasten bulb securely to suction line.
3. Replace compressor.
1. Close the disconnect switch.
2. Check the cause of failure and replace the fuse.
3. Adjust to lower temperature.
4. Turn selector switch knob to "Cool" position.
5. Replace contactor and/or relay.
6. Inspect and secure all electrical connections.
1. High Head Pressure
2. Low Head Pressure
3. Low Suction Pressure
4. High Suction Pressure
5. Compressor will not
start.
1. Excessive charge of refrigerant in system.
2. Inadequate supply of air across the condenser coil.
3. Non-condensate gases in the system.
1. System low on refrigerant.
2. Compressor valves broken.
1. Liquid line valve closed.
2. Restricted liquid line.
3. The bulb of the thermal expansion valve has lost its
charge.
4. System low on refrigerant.
5. Dirty filters.
6. Coil frosted up.
7. Flash gas in the liquid line.
8. Quantity of air through evaporator not adequate.
1. Expansion valve stuck open.
2. Expansion valve bulb not in contact with suction line.
3. Suction and/or discharge valve leaking or broken.
1. Disconnect switch open.
2. Blow fuse or fuse at disconnect switch.
3. Thermostat set too high.
4. Selector switch in "Off" position.
5. Contactor and/or relay coils burned out.
6. Loose or open electrical connection in either the control or power circuit.
3-Phase Scroll Compressor
CAUTION
IM-802 Page 13
Page 14
WIRING DIAGRAM
OUTDOOR POWER SUPPLY
L3
CC
T3
L2
T2
R
SC
COMP
ON
FAN
AUTO
COIL
INDOOR POWER SUPPLY
COOL
OFF
HEAT
24V
G
Y
THERMOSTAT
SYSTEM
SWITCH
W
LOW VOLTAGE
TRANSFORMER
CONTACTOR
COIL
COIL
FAN RELAY
COIL
C
CH
L1
C
T1
FC
MOTOR
P
H
P
L
R
THERMOSTAT
BULB
R
THERMOSTAT
SWITCH
THERMOSTAT
ANTICIPATOR
THERMOSTAT
ADJ. HEAT
ANTICIPATOR
Page 14 IM-802
Page 15
IM-802 Page 15
Page 16
This document contains the most current product information as of this printing. For the most up-to-date
product information, please go to www.mcquay.com.
www.mcquay.com • 800-432-1342
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