Lennox 13ACX, 13ACX-018, 13ACX-024, 13ACX-030, 13ACX-036 Installation Instructions Manual

INSTALLATION

2010 Lennox Industries Inc.

Dallas, Texas, USA

RETAIN THESE INSTRUCTIONS

FOR FUTURE REFERENCE

WARNING

Improper installation, adjustment, alteration, service or
maintenance can cause personal injury, loss of life, or
damage to property.

Installation and service must be performed by a licensed
professional installer (or equivalent) or a service agency.

IMPORTANT

The Clean Air Act of 1990 bans the intentional venting of
refrigerant (CFCs, HCFCs and HFCs) as of July 1, 1992.
Approved methods of recovery, recycling or reclaiming
must be followed. Fines and/or incarceration may be
levied for noncompliance.

INSTRUCTIONS

Merit® Series 13ACX Units

AIR CONDITIONER

506374−01
03/10
Supersedes 11/09

TABLE OF CONTENTS

Shipping and Packing List 1. . . . . . . . . . . . . . . . . . . . . . . .

General 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Typical Unit Parts Arrangement 2. . . . . . . . . . . . . . . . . . .

Model Number Identification 3. . . . . . . . . . . . . . . . . . . . . .

General Information 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Operating Gauge Set and Service Valves 3. . . . . . . . . . .

Recovering Refrigerant from Existing System 5. . . . . . .

New Outdoor Unit Placement 6. . . . . . . . . . . . . . . . . . . . .

New or Replacement Line Set 6. . . . . . . . . . . . . . . . . . . . .

Metering Devices and Flushing the System 10. . . . . . . .

Testing for Leaks 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Evacuating the System 13. . . . . . . . . . . . . . . . . . . . . . . . . .

Electrical Connections 14. . . . . . . . . . . . . . . . . . . . . . . . . .

Servicing Unit Delivered Void of Charge 16. . . . . . . . . . .

Unit Start−Up 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

System Refrigerant 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Removing and Installing Louvers 22. . . . . . . . . . . . . . . . .

System Operation 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Maintenance 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Start−Up and Performance Checklist 24. . . . . . . . . . . . . .

Shipping and Packing List

Litho U.S.A.

IMPORTANT

This unit must be matched with an indoor coil as
specified in Lennox Engineering Handbook. Coils
previously charged with HCFC−22 must be flushed.

WARNING

Electric Shock Hazard. Can cause injury
or death. Unit must be grounded in
accordance with national and local
codes.

Line voltage is present at all components
when unit is not in operation on units with
single-pole contactors. Disconnect all
remote electric power supplies before
opening access panel. Unit may have
multiple power supplies.

03/10 506374−01

Check the unit for shipping damage and listed times below
are intact. If damaged, or if parts are missing, immediately
contact the last shipping carrier.

1  Assembled outdoor unit
1  Refrigerant flow control kit (Fixed Orifice)
1  Liquid line filter drier

General

13ACX, which will also be referred to in this instruction as
the outdoor unit, uses HFC−410A refrigerant. This outdoor
unit must be installed with a matching indoor unit and line
set as outlined in the Lennox 13ACX Engineering
Handbook.

This outdoor unit is designed for use in systems that use
one of the following refrigerant metering devices:

 Thermal expansion valve (TXV)
 Fixed orifice

Page 1

*2P0310* *P506374-01*

Unit Dimensions − Inches (mm)

A

OUTDOOR

COIL FAN

COMPRESSOR

B

SUCTION AND LIQUID

LINE CONNECTION

OPTIONAL UNIT

STANDOFF KIT (4)

SIDE VIEW

Model Numbers A B

−018 24−1/4 (616) 25−1/4 (641)

−024 24−1/4 (616) 25−1/4 (641)

−030 24−1/4 (616) 29−1/4 (743)

−036 24−1/4 (616) 29−1/4 (743)

−042 28−1/4 (724) 29−1/4 (743)

−048 28−1/4 (724) 37−1/4 (925)

−060 28−1/4 (724) 33−1/4 (845)

(FIELD INSTALLED)

DISCHARGE AIR

SIDE VIEW

A

Typical Unit Parts Arrangement

CONTROL

CAPACITOR

GROUND LUG

CONTACTOR

CUTOUT FOR HIGH
VOLTAGE CONDUIT

NOTE  PLUMBING LAYOUT AND COMPRESSOR TYPE MAY VARY SLIGHTLY BETWEEN
MODEL SIZES.

COMPRESS0R

DISCHARGE LINE

COMPRESSOR

HARNESS

OUTDOOR COIL

HIGH PRESSURE

SWITCH (S4)

CONTROL WIRE
LOOP

506374−01 03/10

LIQUID LINE SERVICE VALVE

Page 2

SUCTION LINE SERVICE VALVE

Model Number Identification

AC X13 024 −

Nominal SEER

Unit Type

AC = Air Conditioner

Refrigerant

X = R−410A

WARNING

This product and/or the indoor unit it is matched with may
contain fiberglass wool.

Disturbing the insulation during installation,
maintenance, or repair will expose you to fiberglass wool
dust. Breathing this may cause lung cancer. (Fiberglass
wool is known to the State of California to cause cancer.)

Fiberglass wool may also cause respiratory, skin, and
eye irritation.

To reduce exposure to this substance or for further
information, consult material safety data sheets
available from address shown below, or contact your
supervisor.

Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379−9900

CAUTION

Physical contact with metal edges and corners while
applying excessive force or rapid motion can result in
personal injury. Be aware of, and use caution when
working near these areas during installation or while
servicing this equipment.

General Information

These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
who have jurisdiction before installation.

−−

230

2

Minor Revision Number

Voltage

230 = 208/230V−1phase−60hz

Cooling Capacity − Tons
018 = 1.5

024 = 2
030 = 2.5
036 = 3
042 = 3.5
048 = 4
060 = 5

IMPORTANT

Only use Allen wrenches of sufficient hardness (50Rc −
Rockwell Harness Scale minimum). Fully insert the
wrench into the valve stem recess.

Service valve stems are factory−torqued (from 9 ft−lbs for
small valves, to 25 ft−lbs for large valves) to prevent
refrigerant loss during shipping and handling. Using an
Allen wrench rated at less than 50Rc risks rounding or
breaking off the wrench, or stripping the valve stem
recess.

See the Lennox Service and Application Notes #C−08−1
for further details and information.

IMPORTANT

To prevent stripping of the various caps used, the
appropriately sized wrench should be used and fitted
snugly over the cap before tightening.

When servicing or repairing HVAC components, ensure
the fasteners are appropriately tightened. Table 1 provides
torque values for fasteners.

Table 1. Torque Requirements

Parts Recommended Torque

Service valve cap 8 ft.− lb. 11 NM

Sheet metal screws 16 in.− lb. 2 NM

Machine screws #10 28 in.− lb. 3 NM

Compressor bolts 90 in.− lb. 10 NM

Gauge port seal cap 8 ft.− lb. 11 NM

Operating Gauge Set and Service Valves

These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
who have jurisdiction before installation.

TORQUE REQUIREMENTS

When servicing or repairing heating, ventilating, and air
conditioning components, ensure the fasteners are
appropriately tightened. Table 1 lists torque values for
fasteners.

USING MANIFOLD GAUGE SET

When checking the system charge, only use a manifold
gauge set that features low loss anti−blow back fittings.

Manifold gauge set used with HFC−410A refrigerant
systems must be capable of handling the higher system
operating pressures. The gauges should be rated for use
with pressures of 0 − 800 psig on the high side and a low
side of 30" vacuum to 250 psig with dampened speed to
500 psi. Gauge hoses must be rated for use at up to 800
psig of pressure with a 4000 psig burst rating.

Page 3

13ACX SERIES

OPERATING SERVICE VALVES

The liquid and vapor line service valves are used for
removing refrigerant, flushing, leak testing, evacuating,
checking charge and charging.

SERVICE VALVES

VARIOUS TYPES

OPEN TO BOTH INDOOR AND

OUTDOOR UNITS

SERVICE PORT CAP

SERVICE PORT

TO INDOOR

CORE

UNIT

SERVICE PORT

(VALVE STEM
SHOWN OPEN)
INSERT HEX
WRENCH HERE

Each valve is equipped with a service port which has a
factory−installed valve stem. Figure 1 provides information
on how to access and operating both angle and ball service
valves.

SERVICE PORT CAP

SERVICE PORT

(VALVE STEM SHOWN
CLOSED) INSERT HEX
WRENCH HERE

CLOSED TO BOTH

INDOOR AND OUTDOOR

UNITS

TO INDOOR UNIT

FRONT-SEATED

STEM CAP

SERVICE PORT

CORE

VALVE STEM

TO INDOOR

UNIT

TO OUTDOOR

UNIT

(FRONT−SEATED

STEM CAP

ANGLE−TYPE

SERVICE VALVE

CLOSED)

TO OUTDOOR UNIT

WHEN SERVICE VALVE IS CLOSED, THE SERVICE PORT IS OPEN TO THE
LINE SET AND INDOOR UNIT.

WHEN SERVICE VALVE IS OPEN, THE SERVICE PORT IS OPEN TO LINE SET,
INDOOR AND OUTDOOR UNIT.

To Access Service Port:

A service port cap protects the service port core from contamination and
serves as the primary leak seal.

1. Remove service port cap with an appropriately sized wrench.

2. Connect gauge set to service port.

3. When testing is completed, replace service port cap and tighten as fol­lows:

 With Torque Wrench: Finger tighten and torque cap per Table 1.
 Without Torque Wrench: Finger tighten and use an appropriately

sized wrench to turn an additional 1/6 turn clockwise.

Operating Angle Type Service Valve:

1. Remove stem cap with an appropriately sized wrench.

2. Use a service wrench with a hex−head extension (3/16" for liquid line valve sizes and 5/16" for vapor line valve
sizes) to back the stem out counterclockwise as far as it will go.

ANGLE−TYPE SERVICE VALVE

(BACK−SEATED OPENED)

TO OPEN ROTATE STEM
COUNTERCLOCKWISE 90°.

TO CLOSE ROTATE STEM
CLOCKWISE 90°.

SERVICE PORT

SERVICE PORT CORE

SERVICE PORT CAP

TO OUTDOOR UNIT

1/6 TURN

12

11

10

9

8

1

2

3

4

5

7

6

BALL (SHOWN CLOSED)

BALL−TYPE SERVICE

VAL VE

STEM CAP

Operating Ball Type Service Valve:

1. Remove stem cap with an appropriately sized wrench.

2. Use an appropriately sized wrenched to open. To open valve, rotate stem counterclockwise 90°. To close rotate stem clockwise 90°.

VALVE STEM

Reinstall Stem Cap:

Stem cap protects the valve stem from damage and serves as the primary seal. Replace the stem cap and
tighten as follows:

 With Torque Wrench: Finger tighten and then torque cap per Table 1.
 Without Torque Wrench: Finger tighten and use an appropriately sized wrench to turn

an additional 1/12 turn clockwise.

NOTE  A label with specific torque requirements may be affixed to the stem cap. If the label is present, use the specified torque.

Figure 1. Angle and Ball Service Valves

506374−01 03/10

Page 4

9

10

8

11

1/6 TURN

12

1

2

3

4

5

7

6

Recovering Refrigerant from Existing System

RECOVERING

REFRIGERANT FROM SYSTEM

DISCONNECT POWER

Disconnect all power to the existing outdoor unit at the service

1

disconnect switch or main fuse box/breaker panel.

MAIN FUSE BOX/

BREAKER PANEL

SERVICE

DISCONNECT

SWITCH

RECOVERING REFRIGERANT

Remove existing HCFC−22 refrigerant using one of the following procedures:

3

IMPORTANT  Some system configurations may contain higher than normal refrigerant charge due to either large internal coil volumes,

and/or long line sets.

CONNECT MANIFOLD GAUGE SET

Connect a gauge set, clean recovery cylinder and a recovery

2

machine to the service ports of the existing unit. Use the
instructions provided with the recovery machine to make the
connections.

MANIFOLD GAUGES

RECOVERY MACHINE

LOW

CLEAN RECOVERY
CYLINDER

OUTDOOR UNIT

HIGH

METHOD 1:

Us this method if the existing outdoor unit is not equipped with shut−off valves, or if the unit is not operational and you plan to use the existing
HCFC−22 to flush the system.

Remove all HCFC−22 refrigerant from the existing system. Check gauges after shutdown to confirm that the entire system is completely void of
refrigerant.

METHOD 2:

Use this method if the existing outdoor unit is equipped with manual shut−off valves, and you plan to use new HCFC−22 refrigerant to flush the
system.

The following devices could prevent full system charge recovery into the outdoor unit:

 Outdoor unit’s high or low−pressure switches (if applicable) when tripped can cycle the compressor OFF.
 Compressor can stop pumping due to tripped internal pressure relief valve.
 Compressor has internal vacuum protection that is designed to unload the scrolls (compressor stops pumping) when the pressure ratio meets

a certain value or when the suction pressure is as high as 20 psig. (Compressor suction pressures should never be allowed to go into a vacuum.
Prolonged operation at low suction pressures will result in overheating of the scrolls and permanent damage to the scroll tips, drive bearings and
internal seals.)

Once the compressor can not pump down to a lower pressure due to one of the above system conditions, shut off the vapor valve. Turn OFF the
main power to unit and use a recovery machine to recover any refrigerant left in the indoor coil and line set.

Perform the following task:

A. Start the existing HCFC−22 system in the cooling mode and close the liquid line valve.
B. Use the compressor to pump as much of the existing HCFC−22 refrigerant into the outdoor unit until the outdoor system is full. Turn the outdoor unit

main power OFF and use a recovery machine to remove the remaining refrigerant from the system.

NOTE  It may be necessary to bypass the low pressure switches (if equipped) to ensure complete refrigerant evacuation.

C. When the low side system pressures reach 0 psig, close the vapor line valve.

D. Check gauges after shutdown to confirm that the valves are not allowing refrigerant to flow back into the low side of the system.

Page 5

13ACX SERIES

New Outdoor Unit Placement

See Unit Dimensions on Page 2 for sizing mounting slab,
platforms or supports. Refer to Figure 2 for mandatory
installation clearance requirements.

*

INSTALL UNIT AWAY

FROM WINDOWS

NOTES:

*

*

*

 Service panel access clearance of 30 in. (762 mm) must be

maintained.

 Clearance to one of the other three sides must be 36 in. (914

 Clearance on one of the remaining two sides may be 12 in. (305

.

mm)

mm) and the final side may be 6 in. (152 mm)

.

 Clearance required on top of unit is 48 in. (1219 mm).

 A clearance of 24 in. (610 mm) must be maintained between two

units.

Figure 2. Installation Clearances

POSITIONING CONSIDERATIONS

CAUTION

TWO 90 ELBOWS INSTALLED IN LINE SET

WILL REDUCE LINE SET VIBRATION

Figure 3. Outside Unit Placement

PLACING OUTDOOR UNIT ON SLAB

When installing a unit at grade level, the top of the slab
should be high enough above the grade so that water from
higher ground would not collect around the unit as
illustrated in Figure 4.

DISCHARGE AIR

BUILDING

STRUCTURE

MOUNTING
SLAB

GROUND LEVEL

In order to avoid injury, take proper precaution when lift­ing heavy objects.

Consider the following when positioning the unit:

 Some localities are adopting sound ordinances based

on the unit’s sound level registered from the adjacent
property, not from the installation property. Install the
unit as far as possible from the property line.

 When possible, do not install the unit directly outside

a window. Glass has a very high level of sound
transmission. For proper placement of unit in relation
to a window see the provided illustration in Figure 3.

506374−01 03/10

Figure 4. Typical Slab Mounting at Ground Level

Slab may be level or have a slope tolerance away from the
building of not more than two degrees, or 2 inches per 5
feet (51 mm per 1524 mm) as illustrated in Figure 4.

INSTALLING OUTDOOR UNIT ON ROOF

Install the unit at a minimum of 4 inches (102 mm) above
the surface of the roof. Ensure the weight of the unit is
properly distributed over roof joists and rafters. Redwood
or steel supports are recommended.

New or Replacement Line Set

This section provides information on installation or
replacement of existing line set. If line set is not being
installed or replace then proceed to Brazing Connections
on Page 9.

Page 6

If refrigerant lines are routed through a wall, seal and
isolate the opening so vibration is not transmitted to the
building. Pay close attention to line set isolation during
installation of any HVAC system. When properly isolated
from building structures (walls, ceilings. floors), the
refrigerant lines will not create unnecessary vibration and
subsequent sounds.

Also, consider the following when placing and installing a
high−efficiency air conditioner:

REFRIGERANT LINE SET

Field refrigerant line set consists of liquid and suction lines
from the outdoor unit to the indoor unit coil. Use Lennox
L15 (braze, non−flare) series line set, or field−fabricated
refrigerant lines that meet the specifications listed below.

Table 2. Refrigerant Line Set

Valve Field

−018

−024

−030

−036

−042

−048

−060

Connections

Liquid
Line

3/8 in.

(10 mm)

3/8 in.

(10 mm)

3/8 in.

(10 mm)

Suction
Line

(19 mm)

(22 mm)

1−1/8 in.
(29 mm)

3/4 in.

7/8 in.

Model

NOTE  Some applications may required a field provided 7/8" to
1−1/8" adapter

Recommended Line Set

Liquid
Line

3/8 in

(10 mm)

3/8 in.

(10 mm)

3/8 in.

(10 mm)

Suction
Line

3/4 in.

(19 mm)

7/8in.

(22 mm)

1−1/8 in.
(29 mm)

L15 Line
Set

15 ft. − 50 ft.

(4.6 m −

15 ft. − 50 ft.

(4.6 m −

Fabricated

L15−41

15 m)

L15−65

15 m)

Field

NOTE − When installing refrigerant lines longer than 50
feet, contact Lennox Technical Support Product
Applications for assistance or Lennox piping manual. To
obtain the correct information from Lennox, be sure to
communicate the following points:

 Model (13ACX) and size of unit (e.g. −060).
 Line set diameters for the unit being installed as listed

in Table 2 and total length of installation.

 Number of elbows and if there is a rise or drop of the

piping.

MATCHING WITH NEW OR EXISTING INDOOR COIL
AND LINE SET

The RFC1−metering line consisted of a small bore copper
line that ran from condenser to evaporator coil. Refrigerant
was metered into the evaporator by utilizing
temperature/pressure evaporation effects on refrigerant in
the small RFC line. The length and bore of the RFC line
corresponded to the size of cooling unit.

If the 13ACX is being used with either a new or existing
indoor coil which is equipped with a liquid line which served
as a metering device (RFCI), the liquid line must be
replaced prior to the installation of the 13ACX unit.
Typically a liquid line used to meter flow is 1/4" in diameter
and copper.

LIQUID LINE FILTER DRIER INSTALLATION

The filter drier (one is shipped with each 13ACX unit) must
be field installed in the liquid line between the outdoor unit’s
liquid line service valve and the indoor coil’s metering
device (fixed orifice or TXV) as illustrated in Figure 5. This

filter drier must be installed to ensure a clean,
moisture−free system. Failure to install the filter drier will
void the warranty. A replacement filter drier is available
from Lennox. See Brazing Connections on Page 9 for
special procedures on brazing filter drier connections to
the liquid line.

BRAZE CONNECTION

POINTS

LIQUID

LINE

OUTDOOR

UNIT

LIQUID LINE

SERVICE VALVE

LINE

LIQUID LINE

FILTER DRIER

Figure 5. Typical Liquid Line Filter Drier Installation

CAUTION

Brazing alloys and flux contain materials which are
hazardous to your health.

Avoid breathing vapors or fumes from brazing
operations. Perform operations only in well ventilated
areas.

Wear gloves and protective goggles or face shield to
protect against burns.

Wash hands with soap and water after handling brazing
alloys and flux.

IMPORTANT

The Environmental Protection Agency (EPA) prohibits
the intentional venting of HFC refrigerants during
maintenance, service, repair and disposal of appliance.
Approved methods of recovery, recycling or reclaiming
must be followed.

IMPORTANT

If this unit is being matched with an approved line set
or indoor unit coil which was previously charged with
mineral oil, or if it is being matched with a coil which
was manufactured before January of 1999, the coil
and line set must be flushed prior to installation. Take
care to empty all existing traps. Polyol ester (POE) oils
are used in Lennox units charged with HFC−410A
refrigerant. Residual mineral oil can act as an
insulator, preventing proper heat transfer. It can also
clog the expansion device, and reduce the system
performance and capacity.
Failure to properly flush the system per the
instructions below will void the warranty.

Page 7

13ACX SERIES

LINE SET

INSTALLATION

Line Set Isolation  The following illustrations are

examples of proper refrigerant line set isolation:

REFRIGERANT LINE SET  TRANSITION

FROM VERTICAL TO HORIZONTAL

ANCHORED HEAVY NYLON
WIRE TIE OR AUTOMOTIVE

MUFFLER-TYPE HANGER

AUTOMOTIVE

MUFFLER-TYPE HANGER

IMPORTANT  Refrigerant lines must not contact structure.

REFRIGERANT LINE SET  INSTALLING

VERTICAL RUNS (NEW CONSTRUCTION SHOWN)

NOTE  Insulate liquid line when it is routed through areas where the
surrounding ambient temperature could become higher than the
temperature of the liquid line or when pressure drop is equal to or greater
than 20 psig.

IMPORTANT  Refrigerant lines must not contact wall

OUTSIDE WALL

VAPOR LINE

LIQUID LINE

WALL
STUD

STRAP LIQUID LINE TO
VAPOR LINE

LIQUID LINE

NON−CORROSIVE

METAL SLEEVE

VAPOR LINE − WRAPPED
IN ARMAFLEX

REFRIGERANT LINE SET  INSTALLING

HORIZONTAL RUNS

To hang line set from joist or rafter, use either metal strapping material
or anchored heavy nylon wire ties.

WIRE TIE (AROUND
VAPOR LINE ONLY)

8 FEET (2.43 METERS)

STRAPPING

MATERIAL (AROUND

VAPOR LINE ONLY)

TAPE OR
WIRE TIE

FLOOR JOIST OR

ROOF RAFTER

8 FEET (2.43 METERS)

NON−CORROSIVE
METAL SLEEVE

STRAP THE VAPOR LINE TO THE JOIST
OR RAFTER AT 8 FEET (2.43 METERS)
INTERVALS THEN STRAP THE LIQUID
LINE TO THE VAPOR LINE.

TAPE OR
WIRE TIE

WIRE TIE

INSIDE WALL

WOOD BLOCK

BETWEEN STUDS

SLEEVE

VAPOR LINE WRAPPED

WITH ARMAFLEX

OUTSIDE

WALL

PVC

PIPE

FIBERGLASS

INSULATION

CAULK

STRAP

NON−CORROSIVE
METAL SLEEVE

WIRE TIE

WOOD BLOCK

WIRE TIE

STRAP

LIQUID
LINE

NOTE  Similar installation practices should be used if line set is
to be installed on exterior of outside wall.

FLOOR JOIST OR

ROOF RAFTER

506374−01 03/10

WARNING  Polyol ester (POE) oils used with HFC−410A
refrigerant absorb moisture very quickly. It is very important that the

refrigerant system be kept closed as much as possible. DO NOT
remove line set caps or service valve stub caps until you are ready
to make connections.

Figure 6. Line Set Installation

Page 8

BRAZING

CONNECTIONS

CUT AND DEBUR

Cut ends of the refrigerant lines square

1

(free from nicks or dents) and debur the
ends. The pipe must remain round and do
not pinch end of the line.

ATTACHED GAUGES

A. Connect gauge set low pressure side to liquid line service

3

valve.

B. Connect gauge set center port to bottle of nitrogen with

regulator.

SERVICE PORT MUST BE OPEN TO ALLOW EXIT

INDOOR

UNIT

NOTE − Use silver alloy brazing rods with five or six percent minimum silver
alloy for copper−to−copper brazing, 45 percent alloy for copper−to−brass and
copper−to−steel brazing.

CAP AND CORE REMOVAL

Remove service cap and core

2

from both the vapor and liquid line
service ports.

HIGHLOW

B

ATTACH

POINT FOR NITROGEN

VAPOR LINE

GAUGES

VAPOR LINE

SERVICE

VALV E

OUTDOOR

UNIT

USE REGULATOR TO FLOW

NITROGEN AT 1 TO 2 PSIG.

WRAP SERVICE VALVE

To protect components during

4

brazing, wrap a wet cloth around
the liquid line service valve body
and copper tube stub and use
another wet cloth underneath the
valve body to protect the base
paint.

BRAZE LINE SET

Braze the liquid line to the liquid line

6

service valve. Turn off nitrogen flow.

POINT FLAME AWAY FROM

SERVICE VALVE

LIQUID LINE

LIQUID LINE SERVICE

5

NOTE  The fixed orifice or check
expansion valve metering device at the
indoor unit will allow low pressure
nitrogen to flow through the system.

VALV E

FLOW NITROGEN

Flow regulated nitrogen (at 1 to 2 psig) through the refrigeration
gauge set into the valve stem port connection on the liquid line service
valve and out of the valve stem port connection on the vapor service
valve.

INSTALL SERVICE PORT CAPS ONLY

After all connections have been brazed, disconnect manifold gauge

7

set from service ports, cool down piping with wet rag and remove all
wrappings. Do not reinstall cores until after evacuation procedure.
Reinstall service port caps if desired to close off refrigerant ports.

A

LOW

NITROGEN

HIGH

USE REGULATOR TO

FLOW NITROGEN AT 1

TO 2 PSIG.

NITROGEN

WARNING  Allow braze joint to cool
before removing the wet rag from the
service valve. (TEMPERATURES ABOVE
250ºF CAN DAMAGE VALVE SEALS

IMPORTANT  Connect gauge set low pressure side to vapor
line service valve and repeat procedure starting at paragraph 4
for brazing the liquid line to service port valve.

SERVICE PORT

Figure 7. Brazing Connections

Page 9

SERVICE PORT CORE

SERVICE PORT CAP

13ACX SERIES

Metering Devices and Flushing the System

FLUSHING

LINE SET AND INDOOR COIL (1 OF 2)

TYPICAL FIXED ORIFICE REMOVAL AND
REPLACEMENT PROCEDURE

(Uncased Coil Shown)

1

DISTRIBUTOR TUBES

LIQUID LINE ORIFICE HOUSING

TEFLON RING

FIXED ORIFICE

TWO PIECE PATCH PLATE

(UNCASED COIL ONLY)

DISTRIBUTOR

TUBES

TYPICAL CHECK EXPANSION VALVE

REMOVAL PROCEDURE

(Uncased Coil Shown)

ORIFICE

HOUSING

STUB END

TEFLON
RING

CHECK

EXPANSION

VALV E

TEFLON

RING

LIQUID LINE

SENSING

LINE

BRASS NUT

DISTRIBUTOR

ASSEMBLY

A. On fully cased coils, remove the coil access and plumbing panels.
B. Remove any shipping clamps holding the liquid line and distributor

assembly.

C. Using two wrenches, disconnect liquid line from liquid line orifice

housing. Take care not to twist or damage distributor tubes during
this process.

D. Remove and discard fixed orifice, valve stem assembly if present

and Teflon washer as illustrated above.

E. Use a field−provided fitting to temporary reconnect the liquid line to

the indoor unit’s liquid line orifice housing.

F. Reverse above order to install.

REMOVE AND DISCARD

WHITE TEFLON SEAL (IF

PRESENT)

LIQUID LINE ASSEMBLY

(INCLUDES STRAINER)

CONNECT GAUGES AND EQUIPMENT FOR
FLUSHING PROCEDURE

2

VAPOR LINE

SERVICE VALVE

EXISTING

INDOOR

UNIT

LIQUID LINE SERVICE

RECOVERY

CYLINDER

A. Inverted HCFC−22 cylinder with clean refrigerant to the vapor service

B. HCFC−22 gauge set (low side) to the liquid line valve.
C. HCFC−22 gauge set center port to inlet on the recovery machine with

D. Connect recovery tank to recovery machines per machine

VALV E

LIQUID

D

valve.

an empty recovery tank to the gauge set.

instructions.

INVERTED HCFC−22
CYLINDER CONTAINS
CLEAN HCFC−22 TO BE
USED FOR FLUSHING.

A

1

VAPOR

OUTDOOR

B

NEW

UNIT

C

GAUGE

MANIFOLD

LOW

OPENED

TANK
RETURN

INLET

DISCHARGE

RECOVERY MACHINE

CLOSED

HIGH

OR

A. On fully cased coils, remove the coil access and plumbing panels.
B. Remove any shipping clamps holding the liquid line and distributor as-

C. Disconnect the equalizer line from the check expansion valve equaliz-

D. Remove the vapor line sensing bulb.
E. Disconnect the liquid line from the check expansion valve at the liquid

F. Disconnect the check expansion valve from the liquid line orifice hous-

G. Remove and discard check expansion valve and the two Teflon rings.
H. Use a field−provided fitting to temporary reconnect the liquid line to the

DISTRIBUTOR

ASSEMBLY

MALE EQUALIZER

LINE FITTING

SENSING BULB

sembly.

er line fitting on the vapor line.

line assembly.

ing. Take care not to twist or damage distributor tubes during this pro­cess.

indoor unit’s liquid line orifice housing.

CAUTION This procedure should not be performed on sys­tems which contain contaminants (Example compressor burn
out.

EQUALIZER
LINE

ASSEMBLY WITH

VAPOR

LINE

LIQUID LINE

BRASS NUT

LIQUID

FLUSHING LINE SET

The line set and indoor unit coil must be flushed with at least the

3

same amount of clean refrigerant that previously charged the sys­tem. Check the charge in the flushing cylinder before proceeding.

B

A. Set the recovery machine for liquid recovery and start the recov-

ery machine. Open the gauge set valves to allow the recovery
machine to pull a vacuum on the existing system line set and in­door unit coil.

B. Invert the cylinder of clean HCFC−22 and open its valve to allow

liquid refrigerant to flow into the system through the vapor line
valve. Allow the refrigerant to pass from the cylinder and through
the line set and the indoor unit coil before it enters the recovery
machine.

C. After all of the liquid refrigerant has been recovered, switch the

recovery machine to vapor recovery so that all of the HCFC−22
vapor is recovered. Allow the recovery machine to pull down to 0
the system.

D. Close the valve on the inverted HCFC−22 drum and the gauge

set valves. Pump the remaining refrigerant out of the recovery
machine and turn the machine off.

LINE

506374−01 03/10

Page 10

FLUSHING LINE SET AND INDOOR COIL (2 OF 2)

TYPICAL CHECK EXPANSION VALVE INSTALLATION PROCEDURE

This outdoor unit is designed for use in systems that use check expansion valve metering device. See the Lennox 13ACX Engineering Handbook

4

for approved check expansion valve kit match−ups and application information.

The check expansion valve unit can be installed internal or

TWO PIECE

PATCH PLATE

(UNCASED

COIL ONLY)

DISTRIBUTOR

TUBES

DISTRIBUTOR

ASSEMBLY

MALE EQUALIZER LINE

FITTING (SEE

EQUALIZER LINE

INSTALLATION FOR

FURTHER DETAILS)

SENSING BULB INSULATION IS REQUIRED
IF MOUNTED EXTERNAL TO THE COIL
CASING. SENSING BULB INSTALLATION
FOR BULB POSITIONING.

(Uncased Coil Shown)

LIQUID LINE

ORIFICE

HOUSING

STUB

END

TEFLON
RING

EQUALIZER
LINE

CHECK

EXPANSION

VALV E

LIQUID LINE

ASSEMBLY WITH

BRASS NUT

VAPOR

LINE

external to the indoor coil. In applications where an uncased coil
is being installed in a field−provided plenum, install the check
expansion valve in a manner that will provide access for field
servicing of the check expansion valve. Refer to below
illustration for reference during installation of check expansion
valve unit.

TEFLON

RING

A. Remove the field−provided fitting that temporary reconnected the liquid

line to the indoor unit’s distributor assembly.

SENSING

LINE

LIQUID LINE

B. Install one of the provided Teflon rings around the stubbed end of the

check expansion valve and lightly lubricate the connector threads and
expose surface of the Teflon ring with refrigerant oil.

C. Attach the stubbed end of the check expansion valve to the liquid line

orifice housing. Finger tighten and use an appropriately sized wrench to
turn an additional 1/2 turn clockwise as illustrated in the figure above, or
20 ft−lb.

D. Place the remaining Teflon washer around the other end of the check

expansion valve. Lightly lubricate connector threads and expose sur­face of the Teflon ring with refrigerant oil.

E. Attach the liquid line assembly to the check expansion valve. Finger

tighten and use an appropriately sized wrench to turn an additional 1/2
turn clockwise as illustrated in the figure above or 20 ft−lb.

VAPOR LINE

BULB

12

9

ON LINES SMALLER THAN 7/8",
MOUNT SENSING BULB AT
EITHER THE 3 OR 9 O’CLOCK
POSITION.

BULB

10

8

11

12

7

6

1/2 TURN

1

2

3

4

5

SENSING BULB INSTALLATION

A. Attach the vapor line sensing bulb in the proper orientation

as illustrated to the right using the clamp and screws pro­vided.

NOTE  Confirm proper thermal contact between vapor line
and check expansion bulb before insulating the sensing bulb
once installed.

B. Connect the equalizer line from the

check expansion valve to the
equalizer vapor port on the vapor
line. Finger tighten the flare nut
plus 1/8 turn (7 ft−lbs) as illus­trated below.

10

9

11

12

1

8

7

EQUALIZER LINE INSTALLATION

A. Remove and discard either the flare seal cap or flare nut

with copper flare seal bonnet from the equalizer line port
on the vapor line as illustrated in the figure to the right.

B. Remove and discard either the flare seal cap or flare nut

with copper flare seal bonnet from the equalizer line port on
the vapor line as illustrated in the figure to the right.

5

6

1/8 TURN

2

3

4

VAPOR LINE

FLARE SEAL CAP

ON 7/8" AND LARGER LINES,
MOUNT SENSING BULB AT
EITHER THE 4 OR 8 O’CLOCK

12

BULB

NOTE  NEVER MOUNT ON BOTTOM OF LINE.

OR

POSITION. NEVER MOUNT ON
BOTTOM OF LINE.

BULB

FLARE NUT

COPPER FLARE
SEAL BONNET

MALE BRASS EQUALIZER
LINE FITTING

VAPOR LINE

Page 11

13ACX SERIES

Leak Testing the System

LEAK TEST

LINE SET AND INDOOR COIL

CONNECT GAUGE SET

A. Connect an HFC−410A manifold gauge set high

1

pressure hose to the vapor valve service port.

B. With both manifold valves closed, connect the

cylinder of HFC−410A refrigerant to the center port
of the manifold gauge set.

NOTE  Later in the procedure, the HFC−410A
container will be replaced by the nitrogen container.

NOTE  Normally, the high pressure hose is connected to the liquid line port. How­ever, connecting it to the vapor port better protects the manifold gauge set from high
pressure damage.

HIGHLOW

MANIFOLD GAUGE SET

OUTDOOR UNIT

USE REGULATOR TO FLOW

NITROGEN AT 1 TO 2 PSIG.

NITROGEN

TEST FOR LEAKS

After the line set has been connected to the indoor unit and air conditioner, check the line set connections and

2

indoor unit for leaks. Use the following procedure to test for leaks:
A. With both manifold valves closed, connect the cylinder of HFC−410A refrigerant to the center port of the manifold gauge set. Open

the valve on the HFC−410A cylinder (vapor only).

B. Open the high pressure side of the manifold to allow HFC−410A into the line set and indoor unit. Weigh in a trace amount of

HFC−410A. [A trace amount is a maximum of two ounces (57 g) refrigerant or three pounds (31 kPa) pressure]. Close the valve on
the HFC−410A cylinder and the valve on the high pressure side of the manifold gauge set. Disconnect the HFC−410A cylinder.

C. Connect a cylinder of dry nitrogen with a pressure regulating valve to the center port of the manifold gauge set.

D. Adjust dry nitrogen pressure to 150 psig (1034 kPa). Open the valve on the high side of the manifold gauge set in order to pressurize the

line set and the indoor unit.

E. After a few minutes, open one of the service valve ports and verify that the refrigerant added to the system earlier is measurable

with a leak detector.

F. After leak testing disconnect gauges from service ports.

HFC−410A

WARNING

When using a high pressure gas such as
dry nitrogen to pressurize a refrigeration
or air conditioning system, use a
regulator that can control the pressure
down to 1 or 2 psig (6.9 to 13.8 kPa).

WARNING

Refrigerant can be harmful if it is inhaled. Refrigerant
must be used and recovered responsibly.

Failure to follow this warning may result in personal injury
or death.

B

TO VAPOR

SERVICE VALVE

Fire, Explosion and Personal Safety
Hazard.

Failure to follow this warning could
result in damage, personal injury or
death.

Never use oxygen to pressurize or
purge refrigeration lines. Oxygen,
when exposed to a spark or open
flame, can cause damage by fire
and/or an explosion, that could result
in personal injury or death.

IMPORTANT

A

WARNING

506374−01 03/10

Leak detector must be capable of sensing HFC
refrigerant.

Page 12

Evacuating the System

EVACUATING

LINE SET AND INDOOR COIL

CONNECT GAUGE SET

NOTE  Remove cores from service valves (if not al­ready done).

1

A. Connect low side of manifold gauge

set with 1/4 SAE in−line tee to vapor line
service valve

B. Connect high side of manifold gauge

set to liquid line service valve

C. Connect micron gauge available

connector on the 1/4 SAE in−line tee.

D. Connect the vacuum pump (with

vacuum gauge) to the center port of the
manifold gauge set. The center port line
will be used later for both the HFC−410A
and nitrogen containers.

USE REGULATOR TO FLOW

NITROGEN AT 1 TO 2 PSIG.

HFC−410A

VACUUM PUMP

OUTDOOR

UNIT

A

B

A34000 1/4 SAE TEE WITH
SWIVEL COUPLER

500

C

D

MICRON

GAUGE

TO VAPOR

SERVICE VALVE

TO LIQUID LINE
SERVICE VALVE

LOW

MANIFOLD

GAUGE SET

HIGH

NITROGEN

EVACUATE THE SYSTEM

A. Open both manifold valves and start the vacuum pump.

2

B. Evacuate the line set and indoor unit to an absolute pressure of 23,000 microns (29.01 inches of mercury).

NOTE  During the early stages of evacuation, it is desirable to close the manifold gauge valve at least once. A rapid rise in pressure
indicates a relatively large leak. If this occurs, repeat the leak testing procedure.

NOTE  The term absolute pressure means the total actual pressure within a given volume or system, above the absolute zero of
pressure. Absolute pressure in a vacuum is equal to atmospheric pressure minus vacuum pressure.

C. When the absolute pressure reaches 23,000 microns (29.01 inches of mercury), close the manifold gauge valves, turn off the vacuum

pump and disconnect the manifold gauge center port hose from vacuum pump. Attach the manifold center port hose to a dry nitrogen
cylinder with pressure regulator set to 150 psig (1034 kPa) and purge the hose. Open the manifold gauge valves to break the vacuum in
the line set and indoor unit. Close the manifold gauge valves.

D. Shut off the dry nitrogen cylinder and remove the manifold gauge hose from the cylinder. Open the manifold gauge valves to release the

dry nitrogen from the line set and indoor unit.

E. Reconnect the manifold gauge to the vacuum pump, turn the pump on, and continue to evacuate the line set and indoor unit until the

absolute pressure does not rise above 500 microns (29.9 inches of mercury) within a 20−minute period after shutting off the vacuum pump
and closing the manifold gauge valves.

F. When the absolute pressure requirement above has been met, disconnect the manifold hose from the vacuum pump and connect it to

an upright cylinder of HFC−410A refrigerant. Open the manifold gauge valve 1 to 2 psig in order to release the vacuum in the line set and
indoor unit.

G. Perform the following:

RECOMMEND

MINIMUM 3/8" HOSE

 Close manifold gauge valves.
 Shut off HFC−410A cylinder.
 Reinstall service valve cores by removing manifold hose from service valve. Quickly install cores with

core tool while maintaining a positive system pressure.

 Replace the stem caps and secure finger tight, then tighten an additional one−sixth (1/6) of a turn as

illustrated.

11

10

9

8

7

12

6

1/6 TURN

1

2

3

4

5

Page 13

13ACX SERIES

IMPORTANT

Use a thermocouple or thermistor electronic vacuum
gauge that is calibrated in microns. Use an instrument
capable of accurately measuring down to 50 microns.

WARNING

Danger of Equipment Damage. Avoid deep vacuum
operation. Do not use compressors to evacuate a
system. Extremely low vacuums can cause internal
arcing and compressor failure. Damage caused by
deep vacuum operation will void warranty.

Evacuating the system of non−condensables is critical for
proper operation of the unit. Non−condensables are

defined as any gas that will not condense under
temperatures and pressures present during operation of
an air conditioning system. Non−condensables and water
suction combine with refrigerant to produce substances
that corrode copper piping and compressor parts.

Electrical

In the U.S.A., wiring must conform with current local codes
and the current National Electric Code (NEC). In Canada,
wiring must conform with current local codes and the current
Canadian Electrical Code (CEC).

Refer to the furnace or air handler installation instructions
for additional wiring application diagrams and refer to unit
nameplate for minimum circuit ampacity and maximum
overcurrent protection size.

24VAC TRANSFORMER

Use the transformer provided with the furnace or air
handler for low-voltage control power (24VAC − 40 VA
minimum)

SIZE CIRCUIT AND INSTALL SERVICE
DISCONNECT SWITCH

Refer to the unit nameplate for minimum circuit ampacity, and maximum
fuse or circuit breaker (HACR per NEC). Install power wiring and properly
sized disconnect switch.

MAIN FUSE BOX/

BREAKER PANEL

SERVICE

DISCONNECT

SWITCH

NOTE  Units are approved for use only with copper conductors.
Ground unit at disconnect switch or to an earth ground.

WARNING

Electric Shock Hazard. Can cause injury or death. Unit must be grounded in accordance with national and
local codes.

Line voltage is present at all components when unit is not in operation on units with single-pole contactors.
Disconnect all remote electric power supplies before opening access panel. Unit may have multiple power
supplies.

INSTALL THERMOSTAT

Install room thermostat (ordered separately) on an inside wall
approximately in the center of the conditioned area and 5 feet (1.5m) from
the floor. It should not be installed on an outside wall or where it can be
affected by sunlight or drafts.

THERMOSTAT

5 FEET

(1.5M)

NOTE  24VAC, Class II circuit connections are made in the control
panel.

506374−01 03/10

Page 14

ROUTING HIGH VOLTAGE/ GROUND AND CONTROL WIRING

HIGH VOLTAGE / GROUND WIRES

Any excess high voltage field wiring should be trimmed and
secured away from any low voltage field wiring. To facilitate a
conduit, a cutout is located in the bottom of the control panel.
Connect conduit to the control panel using a proper conduit fitting.

HIGH VOLTAGE

CONNECTIONS

(CONTACTOR)

CONTROL WIRING

NOTE  Wire tie provides low voltage control wire strain relief and to
maintain separation of field installed low and high voltage circuits.

NOTE  For proper voltages, select thermostat wire (control wires)
gauge per Table above.

NOTE  Do not bundle any excess 24VAC control wires inside
control panel.

HIGH VOLTAGE
FIELD WIRING

LOW VOLTAGE
FIELD WIRING

FACTORY
WIRING

Install low voltage wiring from outdoor to indoor unit and from thermostat
to indoor unit as illustrated.

A. Run 24VAC control wires through hole with grommet and secure with

provided wire tie.

B. Make 24VAC thermostat wire connections. Locate the two wires from the

contactor and make connection using field provided wire nuts:

 Yellow to Y1
 Black to C (common)

WIRE RUN LENGTH AWG# INSULATION TYPE

LESS THAN 100’ (30 METERS) 18 TEMPERATURE RATING

MORE THAN 100’ (30 METERS) 16 35ºC MINIMUM.

SINGLE PHASE

GROUND

THERMOSTAT INDOOR UNIT

W1

G

C

R

Y

POWER

HEAT

COOLING

INDOOR

BLOWER

COMMON

R

W

Y

G

C

B

CONTROL

WIRING

HIGH VOLTAGE
FLEXIBLE CONDUIT

AND WIRE TIE

OUTDOOR

UNIT

Y1

C

A

GROMMET

Figure 8. Typical 13ACX Unit Wiring Diagram

Page 15

13ACX SERIES

GAUGE SET

CONNECTIONS FOR TESTING AND CHARGING

SUCTION LINE

B

SERVICE PORT
CONNECTION

REFRIGERANT TANK

MANIFOLD GAUGE SET

LOW

HIGH

OUTDOOR UNIT

CHARGE IN

LIQUID PHASE

DIGITAL SCALE

A

D

TEMPERATURE

SENSOR

LINE SERVICE

A. Close manifold gauge set valves and connect the center hose to a cylinder of HFC−410A. Set for liquid phase charging.

B. Connect the manifold gauge set’s low pressure side to the suction line service port.

C. Connect the manifold gauge set’s high pressure side to the liquid line service port.

D. Position temperature sensor on liquid line near liquid line service port.

TO LIQUID

VALV E

C

Figure 9. Gauge Set Setup and Connections

Servicing Units Delivered Void of Charge

If the outdoor unit is void of refrigerant, clean the system
using the procedure described below.

1. Leak check system using procedure outlined on Page

12.

2. Evacuate the system using procedure outlined on
Page 13.

3. Use nitrogen to break the vacuum and install a new
filter drier in the system.

4. Evacuate the system again using procedure outlined
on Page 13.

5. Weigh in refrigerant using procedure outlined under

Start−Up and Charging Procedures.

6. Monitor the system to determine the amount of
moisture remaining in the oil. It may be necessary to
replace the filter drier several times to achieve the
required dryness level. If system dryness is not

verified, the compressor will fail in the future.

Unit Start−Up

2. Inspect all factory− and field−installed wiring for loose
connections.

3. After evacuation is complete, open the liquid line and
suction line service valves to release the refrigerant
charge (contained in air conditioner) into the system.

4. Replace the stem caps and tighten to the value listed
in Table 1.

5. Check voltage supply at the disconnect switch. The
voltage must be within the range listed on the unit’s
nameplate. If not, do not start the equipment until you
have consulted with the power company and the
voltage condition has been corrected.

6. Set the thermostat for a cooling demand. Turn on
power to the indoor handler and close the air
conditioner disconnect switch to start the unit.

7. Recheck voltage while the unit is running. Power must
be within range shown on the nameplate.

8. Check system for sufficient refrigerate using the
procedures that follow.

TEMPERATURE SENSOR

(LIQUID LINE)

IMPORTANT

If unit is equipped with a crankcase heater, it should be
energized 24 hours before unit start−up to prevent
compressor damage as a result of slugging.

1. Rotate fan to check for binding.

506374−01 03/10

System Refrigerant

This section outlines procedures for:

1. Connecting gauge set for testing and charging;

2. Checking and adjusting indoor airflow;

3. Adding or removing refrigerant.

Page 16

ADDING OR REMOVING REFRIGERANT

This system uses HFC−410A refrigerant which operates at much higher pressures than HCFC−22. The pre−installed liquid
line filter drier is approved for use with HFC−410A only. Do not replace it with components designed for use with HCFC−22.
This unit is NOT approved for use with coils which use capillary tubes or fixed orifices as a refrigerant metering device.

Check airflow using the Delta−T (

DT) process using the illustration in Figure 10.

AIRFLOW

INDOOR COIL

Temperature of air
entering indoor
coil ºF

A

Wet−bulb ºF

80 24 24 24 23 23 22 22 22 20 19 18 17 16 15
78 23 23 23 22 22 21 21 20 19 18 17 16 15 14
76 22 22 22 21 21 20 19 19 18 17 16 15 14 13

Dry−bulb

74 21 21 21 20 19 19 18 17 16 16 15 14 13 12
72 20 20 19 18 17 17 16 15 15 14 13 12 11 10
70 19 19 18 18 17 17 16 15 15 14 13 12 11 10

57 58 59 60 61 62 63 64 65 66 67 68 69 70

DT

DRY

BULB

C

53º

T

19º

Drop

air flow

air flow

B

B

64º

All temperatures are expressed in ºF

INDOOR COIL

WET BULB

Use the following procedure to adjust for optimal air flow across the indoor coil:

1. Determine the desired DT  Measure entering air temperature using dry bulb (A) and wet bulb (B). DT
is the intersecting value of A and B in the Table (see triangle).

2. Find temperature drop across coil  Measure the coil’s dry bulb entering and leaving air temperatures
(A and C). Temperature Drop Formula: (T

3. Determine if fan needs adjustment  If the difference between the measured T

DT (T

–DT) is within +3º, no adjustment is needed. See example below:

Drop

) = A minus C.

Drop

and the desired

Drop

Assume DT = 15 and A temp. = 72º, these C temperatures would necessitate stated actions:

A

72º

DRY BULB

Cº T

53º 19 – 15 = 4 Increase the airflow
58º 14 – 15 = −1 (within +3º range) no change
62º 10 – 15 = −5 Decrease the airflow

– DT = ºF ACTION

Drop

4. Adjust the fan speed  See indoor unit instructions to increase/decrease fan speed.

Figure 10. Checking Indoor Airflow over Evaporator Coil using Delta−T (DT) Chart

Changing air flow affects all temperatures; recheck
temperatures to confirm that the temperature drop
and DT are within +3º.

Page 17

13ACX SERIES

START: Determine how refrigerant is metered

WHEN TO CHARGE?

 Warm weather best
 Can charge in colder weather

CHARGE METHOD? Determine by:

 Metering device type
 Outdoor ambient temperature

REQUIREMENTS:

 Sufficient heat load in structure
 Indoor temperature between 70-80ºF

(21−26ºC)

(18.3ºC) and

Above

 Manifold gauge set connected to unit
 Thermometers:

− to measure outdoor ambient
temperature

− to measure liquid line temperature

− to measure suction line
temperature

APPROACH OR

SUBCOOLING

Figure 11. Determining Charge Method

65ºF

TXV

64ºF

(17.7ºC) and

Below

WEIGH-IN

Which

metering

device?

40ºF

(4.4ºC) and

Above

RFC

39ºF

(3.8ºC) and

Below

WEIGH-INSUPERHEAT

START: Measure outdoor ambient temperature

USE EITHER APPROACH

OR SUBCOOLING

METHOD

65ºF

(18.3ºC) and

Above

WEIGH IN TXV

Refrigerant Charge per Line Set Length

Liquid Line

Set Diameter

3/8" (9.5 mm)

NOTE − *If line length is greater than 15 ft. (4.6 m), add this
amount. If line length is less than 15 ft. (4.6 m), subtract this
amount.

Ounces per 5 feet (g per 1.5 m)

adjust from 15 feet (4.6 m) line set*

3 ounce per 5’ (85 g per 1.5 m)

Figure 12. HFC−410A Weigh In TXV Method

(17.7ºC) and

ABOVE or

BELOW

64ºF

Below

1. Check Liquid and suction line pressures

2. Compare unit pressures with Table 3,
Normal Operating Pressures.

3. Conduct leak check; evacuate as
previously outlined.

4. Weigh in the unit nameplate charge plus
any charge required for line set differences
over feet.

This nameplate is for illustration
purposes only. Go to actual
nameplate on outdoor unit for
charge information.

506374−01 03/10

Page 18

START: Measure outdoor ambient temperature

DO NOT CHARGE UNIT

USE WEIGH-IN METHOD

(Results of charging at low

Weigh-in or remove refriger-

temperatures not reliable)

ant based upon line length

If refrigerant is added
or removed, retest to
confirm that unit is
properly charged.

64ºF

(17.7ºC) and

Below

(18.3ºC) and

ABOVE or

BELOW

65ºF

Above

1. Confirm proper airflow across coil using Figure

10.

2. Compare unit pressures with Table 3, Normal
Operating Pressures.

3. Set thermostat to call for heat (must have a
cooling load between 70-80ºF (21−26ºC).

4. Connect gauge set.

5. When heat demand is satisfied, set thermostat
to call for cooling.

6. Allow temperatures and pressures to stabilize.

7. Record outdoor ambient temperature:

AMBº =_________

8. Record liquid line temperature:

LIQº = __________

9. Subtract to determine approach (APPº):

LIQº_____ − AMBº _____ = APPº_____

10. Compare results with table below.

If value is greater than shown (high approach),
add refrigerant; if less than shown (liquid
temperature too close to ambient temperature,
low approach), remove refrigerant.

Figure 13. HFC−410A Approach TXV Charge

START: Measure outdoor ambient temperature

USE WEIGH-IN METHOD

DO NOT CHARGE UNIT

Weigh-in or remove refrigerant

(Results of charging at low

based upon line length

temperatures not reliable)

CARDBOARD OR
PLASTIC SHEET

If refrigerant is added
or removed, verify
charge using the
Approach Method.

64ºF

(17.7ºC) and

Below

BLOCK OUTDOOR COIL: [sometimes necessary
with lower temperatures] Use cardboard or plastic
sheet to restrict the airflow through the outdoor coil
to achieve pressures from 325−375 psig
(2240−2585 kPa). Higher pressures are needed to
check charge. Block equal sections of air intake
panels and move coverings sideways until the
liquid pressure is in the above noted ranges.

If value is MORE
than shown, remove
refrigerant.

APPº (Approach) Values(F:+/−1.0° [C: +/−0.6°])

ºF (ºC)* −018 −024 −030 −036 −042 −048 −060
Any 4 (2.2) 8 (4.4) 8 (4.4) 11 (6.1) 9 (5.0) 8 (4.4) 9 (5.0)
*Temperature of air entering outdoor coil

65ºF

(18.3ºC) and

Above

ABOVE or

BELOW

1. Confirm proper airflow across coil using Figure

10.

2. Compare unit pressures with Table 3, Normal
Operating Pressures.

3. Set thermostat to call for heat (must have a

cooling load between 70-80ºF (21−26ºC)

4. Connect gauge set

5. Measure outdoor ambient temperature

6. When heat demand is satisfied, set thermostat to

call for cooling

7. Allow temperatures and pressures to stabilize.

NOTE − If necessary, block outdoor coil to
maintain 325 − 375 psig.

8. Record liquid line temperature:

LIQº = ______

9. Measure liquid line pressure and use the value to

determine saturation temperature (see Table 4):

SATº = ______

10. Subtract to determine subcooling (SCº):

SATº_____ − LIQº _____ = SCº _____

11. Compare results with table below.

If value is LESS
than shown, add
refrigerant.

Figure 14. HFC−410A Subcooling TXV Charge

MORE or

LESS

SCº (Subcooling) Values (F:+/−1.0° [C: +/−0.6°])

ºF (ºC)* −018 −024 −030 −036 −042 −048 −060
Any 10 (5.6) 10 (5.6) 9 (5.0) 12 (6.7) 9 (5.0) 9 (5.0) 7 (3.9)
*Temperature of air entering outdoor coil

Page 19

13ACX SERIES

START: Measure outdoor ambient temperature

USE SUPERHEAT

40ºF

(4.4ºC) and

Above

WEIGH IN RFC

Refrigerant Charge per Line Set Length

(3.8ºC) and

ABOVE or

BELOW

39ºF

Below

1. Check Liquid and suction line pressures

2. Compare unit pressures with Table 3,

Normal Operating Pressures.

3. Conduct leak check; evacuate as

previously outlined.

4. Weigh in the unit nameplate charge plus

any charge required for line set differences
over feet.

Liquid Line

Set Diameter

3/8" (9.5 mm)

NOTE − *If line length is greater than 15 ft. (4.6 m), add this
amount. If line length is less than 15 ft. (4.6 m), subtract this
amount.

Ounces per 5 feet (g per 1.5 m)

adjust from 15 feet (4.6 m) line set*

3 ounce per 5’ (85 g per 1.5 m)

Figure 15. HFC−410A Weigh In RFC Method

START: Measure outdoor ambient temperature

USE WEIGH-IN METHOD

Weigh-in or remove refrigerant
based upon line length

Wet Bulb (air entering indoor coil)
ºF* 50 52 54 56 58 60 62 64 66 68 70 72 74 76
40 15 18 20 23 26 29 32 34 38 41 43 46 48 51
45 13 16 18 21 24 27 30 33 36 39 41 44 46 49
50 11 14 16 19 22 25 28 31 34 37 39 42 44 47
55 9 12141720232730333638404244
60 7 10121518212427303335384043
65 - 6 10 13 16 19 21 24 27 30 33 36 38 41
70 - - 7 1013161921242730333639
75 - - - 6 9 121518212428313437
80 - - - - 5 8 12 15 18 21 25 28 31 35
85 - - - - - - 8 11 15 19 22 26 30 33
90 - - - - - - 5 9 131620242731
95 - - - - - - - 6 101418222529
100 --------81216212428

If refrigerant is
REMOVED, retest to
confirm that unit is
properly charged.

105 --------5913172226
110 ---------611152025
115 ----------8141824

* Dry−bulb temperature (ºF) of entering outdoor ambient air.

(3.8ºC) and

Below

SHº (Superheat) Values (+/−5ºF)

ABOVE or

BELOW39ºF

40ºF

(4.4ºC) and

Above

This nameplate is for illustration purposes
only. Go to actual nameplate on outdoor unit
for charge information.

1. Confirm proper airflow across coil using Figure

10.

2. Compare unit pressures with Table 3, Normal
Operating Pressures.

3. Use SUPERHEAT to correctly charge unit or to
verify the charge is correct.

4. Set thermostat to call for heat (must have a cooling
load between 70-80ºF (21−26ºC)

5. Connect gauge set.

6. When heat demand is satisfied, set thermostat to
call for cooling.

7. Allow temperatures and pressures to stabilize.

8. Measure the suction line pressure and use the use
value to determine saturation temperature (Table

4):

SATº =_________

9. Record suction line temperature:

VAPº =_________

10. Subtract to determine superheat (SHº):

VAPº − _____ SATº ______ = SHº______

11. Record the wet bulb temperature (air entering
indoor coil):

WB =_______

12. Record outdoor ambient temperature.

13. Compare results with table to the left.

NOTE − Do not attempt to charge system where a
dash appears, system could be overcharged.
Superheat is taken at suction line service port.
Suction line superheat must never be less than 5ºF
at the suction line service port.

If value is LESS than
shown, then REMOVE
refrigerant.

Figure 16. HFC−410A Superheat RFC Method

506374−01 03/10

MORE or

LESS

If value is MORE
than shown, then
ADD refrigerant.

Page 20

If refrigerant is
ADDED, retest to
confirm that unit is
properly charged.

Table 3. HFC−410A Normal Operating Pressures (Liquid +10 and Suction +5 psig)

Use this table to perform maintenance checks; it is not a procedure for charging the
system. Minor variations in these pressures may be due to differences in installations.

IMPORTANT

Significant deviations could mean that the system is not properly charged or that a
problem exists with some component in the system.

13ACX

5F (5C)* Liquid / Suction Liquid / Suction Liquid / Suction Liquid / Suction Liquid / Suction Liquid / Suction Liquid / Suction

Expansion Valve (TXV)

65 (18) 233 / 132 244 / 137 248 / 127 263 / 135 238 /132 235 / 132 241 / 130

70 (21) 251 / 133 263 / 138 263 / 131 281 / 138 262 / 133 254 / 132 260 / 130

75 (24) 265 / 133 285 / 139 284 / 132 302 / 140 280 / 134 276 / 134 280 / 132

80 (27) 292 / 135 307 / 140 307 / 134 325 / 142 301 / 136 298 / 134 299 / 134

85 (29) 314 / 136 329 / 141 330 / 135 349 / 142 327 / 137 323 / 135 321 / 135

90 (32) 338 / 137 354 / 142 355 / 136 375 / 143 353 / 138 350 / 137 344 / 134

95 (35) 362 / 138 379 / 143 380 / 137 404 / 144 377 / 140 377 / 138 371 / 135

100 (38) 388 / 140 404 / 144 407 / 138 433 / 145 404 / 141 406 / 140 400 / 137

105 (41) 415 / 141 438 / 145 434 / 139 462 / 147 435 / 142 430 / 141 428 / 139

110 (43) 444 / 142 464 / 147 465 / 141 494 / 149 465 / 143 464 / 142 458 / 141

115 (45) 475 / 143 495 / 148 497 / 142 527 / 150 499 / 144 495 / 143 484 / 142

Fixed Orifice (RFC)

65 (18) 233 / 121 246 / 126 245 / 123 261 / 134 246 / 126 247 / 125 248 / 124

70 (21) 250 / 124 265 / 129 265 / 126 281 / 136 263 / 128 266 / 128 266 / 126

75 (24) 270 / 128 286 / 132 286 / 129 301 / 138 284 / 131 286 / 131 288 / 130

80 (27) 291 / 131 307 /135 308 / 132 324 / 140 305 / 133 307 / 133 309 / 133

85 (29) 313 / 134 330 / 137 331 / 135 346 / 142 327 / 135 329 / 135 330 / 135

90 (32) 335 / 136 353 / 140 355 / 138 371 / 144 350 / 138 353 / 138 354 / 138

95 (35) 359 / 138 378 / 142 380 / 140 396 / 146 374 / 140 377 / 140 377 / 140

100 (38) 383 / 140 402 / 143 405 / 142 422 / 148 399 / 142 403 / 142 406 / 142

105 (41) 409 / 142 428 / 145 431 / 144 448 / 150 424 / 144 428 / 144 431 / 144

110 (43) 436 / 145 456 / 147 458 / 146 477 / 151 452 / 146 455 / 146 457 / 146

115 (46) 464 / 147 486 / 149 487 / 148 506 / 153 481 / 148 483 / 147 484 / 148

*Values shown are typical pressures; indoor unit match up, indoor air quality equipment, and indoor load will cause the pressures to vary.
**Temperature of the air entering the outside coil.

−018 −024 −030 −036 −042 −048 −060

Table 4. HFC−410A Temperature  Pressure (Psig)

°F °C Psig °F °C Psig

−40 −40.0 11.6 60 15.6 170

−35 −37.2 14.9 65 18.3 185

−30 −34.4 18.5 70 21.1 201

−25 −31.7 22.5 75 23.9 217

−20 −28.9 26.9 80 26.7 235

−15 −26.1 31.7 85 29.4 254

−10 −23.3 36.8 90 32.2 274

−5 −20.6 42.5 95 35.0 295
0 −17.8 48.6 100 37.8 317
5 −15.0 55.2 105 40.6 340

10 −12.2 62.3 110 43.3 365
15 −9.4 70.0 115 46.1 391
20 −6.7 78.3 120 48.9 418
25 −3.9 87.3
30 −1.1 96.8 130 54.4 476
35 1.7 107 135 57.2 507
40 4.4 11 8 140 60.0 539
45 7.2 130
50 10.0 142
55 12.8 155

125 51.7 446

145 62.8 573
150 65.6 608

Page 21

13ACX SERIES

Removing and Installing Louvers

WARNING

To prevent personal injury, or damage to panels, unit or structure, be sure to observe the following:

While installing or servicing this unit, carefully stow all removed panels out of the way, so that the panels will not cause injury to personnel,
nor cause damage to objects or structures nearby, nor will the panels be subjected to damage (e.g., being bent or scratched).

While handling or stowing the panels, consider any weather conditions, especially windy conditions, that may cause panels to be blown
around and battered.

ORDER OF REMOVAL AND REINSTALLATION

When removing the unit panels. Remove panel A
first, then B, C and finally D. When reinstalling pan­els, reverse that order starting with panel D, C, B
and finally A.

REMOVAL

STEP 1

TO REMOVE PANEL,
REMOVE MOUNTING
SCREWS SECURING
PANEL TO THE UNIT.

PANEL A

PANEL B

PANEL A

PANEL C

WARNING

PANEL D

INSTALLATION

TOP CAP

STEP 1

STARTING WITH PANEL D,
INSERT PANEL UNDER UNIT
TOP CAP LIP AND LIFT
SLIGHTLY TO CLEAR SIDE LIP
OF PANEL FROM BASE.

SIDE

GROOVE

STEP 2

SLIGHTLY LIFT PANEL A IN
ORDER TO CLEAR SIDE
LIPS OF PANEL FROM
BASE OF UNIT.

STEP 3

TILT PANEL OUT SLIGHTLY
AND PULL DOWNWARD
TO REMOVE.

REPEAT STEPS 1, 2 AND
3 TO REMOVE PANELS B,
C AND FINALLY D.

PANEL A

506374−01 03/10

STEP 2

MOVE PANEL IN TOWARDS UNIT.
ALIGN LEFT/RIGHT SIDE LIPS OF
PANEL WITH GROOVE INSERTS
ALONG LEFT/RIGHT SIDE OF UNIT.

STEP 3

SECURE PANEL, WITH
MOUNTING SCREWS.

REPEAT STEPS 1 AND 2 TO INSTALL PANELS C,
B AND FINALLY A.

BASE

Page 22

PANEL D

System Operation

The outdoor unit and indoor blower will cycle on and off as
dictated by demands from the room thermostat. When the
thermostat’s blower switch is in the ON position, the indoor
blower will operate continuously.

HIGH PRESSURE SWITCH

13ACX units are equipped with a high-pressure switch that
is located in the liquid line of the compressor as illustrated
in figure on Page 2.

The switch is a Single Pole, Single Throw (SPST),
manual−reset switch which is normally closed and
removes power from the compressor when discharge
pressure rises above factory setting at 590 + 10 psi. The
manual−reset switch can be identified by a red cap that is
press to preform the reset function.

Maintenance

DEALER

WARNING

Electric shock hazard. Can cause injury
or death. Before attempting to perform
any service or maintenance, turn the
electrical power to unit OFF at disconnect
switch(es). Unit may have multiple power
supplies.

WARNING

Improper installation, adjustment, alteration, service or
maintenance can cause personal injury, loss of life, or
damage to property.

Installation and service must be performed by a licensed
professional installer (or equivalent) or a service agency.

Maintenance and service must be performed by a qualified
installer or service agency. At the beginning of each
cooling season, the system should be checked as follows:

Outdoor Unit

1. Outdoor unit fan motor is pre−lubricated and sealed.
No further lubrication is needed.

2. Visually inspect all connecting lines, joints and coils for
evidence of oil leaks.

3. Check all wiring for loose connections.

4. Check for correct voltage at unit (unit operating).

5. Check amp draw on outdoor fan motor.

Motor Nameplate:_________ Actual:__________.

6. Inspect drain holes in coil compartment base and
clean if necessary.

NOTE - If insufficient cooling occurs, the unit should be
gauged and refrigerant charge should be checked.

NOTE  It may be necessary to flush the outdoor coil
more frequently if it is exposed to substances which are
corrosive or which block airflow across the coil (e.g., pet
urine, cottonwood seeds, fertilizers, fluids that may contain
high levels of corrosive chemicals such as salts)

Sea Coast  Moist air in ocean locations can carry salt,
which is corrosive to most metal. Units that are located
near the ocean require frequent inspections and
maintenance. These inspections will determine the
necessary need to wash the unit including the outdoor coil.
Consult your installing contractor for proper
intervals/procedures for your geographic area or service
contract.

Indoor Unit

1. Clean or change filters.

2. Lennox blower motors are prelubricated and
permanently sealed. No more lubrication is needed.

3. Adjust blower speed for cooling. Measure the pressure
drop over the coil to determine the correct blower CFM.
Refer to the unit information service manual for pressure
drop tables and procedure.

4. Belt Drive Blowers − Check belt for wear and proper
tension.

5. Check all wiring for loose connections.

6. Check for correct voltage at unit. (blower operating)

7. Check amp draw on blower motor.

Motor Nameplate:_________ Actual:__________.

Indoor Coil

1. Clean coil if necessary.

2. Check connecting lines, joints and coil for evidence of
oil leaks.

3. Check condensate line and clean if necessary.

HOMEOWNER

Cleaning of the outdoor unit’s coil should be performed by
a trained service technician. Contact your dealer and set
up a schedule (preferably twice a year, but at least once a
year) to inspect and service your outdoor unit. The
following maintenance may be performed by the
homeowner.

CAUTION

Physical contact with metal edges and corners while applying excessive
force or rapid motion can result in personal injury. Be aware of, and use
caution when working near these areas during installation or while
servicing this equipment.

IMPORTANT

Sprinklers and soaker hoses should not be installed
where they could cause prolonged exposure to the
outdoor unit by treated water. Prolonged exposure of the
unit to treated water (i.e., sprinkler systems, soakers,
waste water, etc.) will corrode the surface of steel and
aluminum parts and diminish performance and longevity
of the unit.

Outdoor Coil

Clean and inspect outdoor coil (may be flushed with a
water hose). Ensure power is off before cleaning.

Outdoor Coil

The outdoor unit must be properly maintained to ensure its
proper operation.

Page 23

13ACX SERIES

 Please contact your dealer to schedule proper

inspection and maintenance for your equipment.

 Make sure no obstructions restrict airflow to the

outdoor unit.

 Grass clippings, leaves, or shrubs crowding the unit

can cause the unit to work harder and use more
energy.

 Keep shrubbery trimmed away from the unit and

periodically check for debris which collects around the
unit.

Routine Maintenance

In order to ensure peak performance, your system must be
properly maintained. Clogged filters and blocked airflow
prevent your unit from operating at its most efficient level.

1. Air Filter  Ask your Lennox dealer to show you

where your indoor unit’s filter is located. It will be either
at the indoor unit (installed internal or external to the
cabinet) or behind a return air grille in the wall or
ceiling. Check the filter monthly and clean or replace
it as needed.

2. Disposable Filter  Disposable filters should be

replaced with a filter of the same type and size.

NOTE  If you are unsure about the filter required for your
system, call your Lennox dealer for assistance.

3. Reusable Filter  Many indoor units are equipped

with reusable foam filters. Clean foam filters with a
mild soap and water solution; rinse thoroughly; allow
filter to dry completely before returning it to the unit or
grille.

NOTE  The filter and all access panels must be in place
any time the unit is in operation.

4. Electronic Air Cleaner  Some systems are

equipped with an electronic air cleaner, designed to
remove airborne particles from the air passing through
the cleaner. If your system is so equipped, ask your
dealer for maintenance instructions.

5. Indoor Unit  The indoor unit’s evaporator coil is

equipped with a drain pan to collect condensate
formed as your system removes humidity from the
inside air. Have your dealer show you the location of
the drain line and how to check for obstructions. (This
would also apply to an auxiliary drain, if installed.)

Thermostat Operation

See the ComfortSense® 7000 thermostat homeowner
manual for instructions on how to operate your thermostat.

Preservice Check

If your system fails to operate, check the following before
calling for service:

 Verify room thermostat settings are correct.
 Verify that all electrical disconnect switches are ON.
 Check for any blown fuses or tripped circuit breakers.
 Verify unit access panels are in place.
 Verify air filter is clean.
 If service is needed, locate and write down the unit

model number and have it handy before calling.

Accessories

For update−to−date information, see any of the following
publications:

 Lennox 13ACX Engineering Handbook
 Lennox Product Catalog
 Lennox Price Book

Start−Up and Performance Checklist

Job Name Job no. Date

Job Location City State

Installer City State

Unit Model No. Serial No. Service Technician

Nameplate Voltage

Rated Load Ampacity Compressor Outdoor Fan

Maximum Fuse or Circuit Breaker

Electrical Connections Tight?  Indoor Filter clean?  Supply Voltage (Unit Off)

Indoor Blower RPM S.P. Drop Over Indoor (Dry) Outdoor Coil Entering Air Temp.

Discharge Pressure Suction Pressure Refrigerant Charge Checked? 

Refrigerant Lines: Leak Checked?  Properly Insulated?  Outdoor Fan Checked? 

Service Valves: Fully Opened?  Caps Tight?  Thermostat

Voltage With Compressor Operating Calibrated?  Properly Set?  Level? 

506374−01 03/10

Page 24