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

INSTALLATION

2008 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.

CAUTION

INSTRUCTIONS

Merit® Series 13ACX Units

AIR CONDITIONER

506081−01
09/08
Supersedes 07/08

Table of Contents

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

13ACX Air Conditioners 1. . . . . . . . . . . . . . . . . . . . . . . . . .

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

General Information 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Recovering Refrigerant from Existing System 4. . . . . . .

Removing Existing Outdoor Unit 5. . . . . . . . . . . . . . . . . . .

Positioning New Outdoor Unit 5. . . . . . . . . . . . . . . . . . . . .

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

Brazing Connections 8. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Removing Indoor Unit Metering Device 9. . . . . . . . . . . .

Flushing the System 10. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Installing New Indoor Unit Metering Device 11. . . . . . . . .

Testing for Leaks 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

Servicing Unit Delivered Void of Charge 14. . . . . . . . . . .

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

Start−Up and Charging Procedures 15. . . . . . . . . . . . . . . .

System Operation 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Maintenance 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Homeowner Information 22. . . . . . . . . . . . . . . . . . . . . . . . .

Optional Accessories 23. . . . . . . . . . . . . . . . . . . . . . . . . . .

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

Litho U.S.A.

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

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.

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.

09/08 506081−01

Page 1

Shipping and Packing List

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

13ACX Air Conditioners

13ACX Air Conditioners, 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

*2P0908* *P506081-01*

Unit Dimensions − Inches (mm)

A

A

OUTDOOR COIL FAN

COMPRESSOR

DISCHARGE AIR

B

OPTIONAL UNIT STANDOFF KIT

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)

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

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.

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

SUCTION AND LIQUID LINE

(4) (FIELD INSTALLED)

CONNECTION

SIDE VIEW

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

USING MANIFOLD GAUGE SETS

When checking the system charge, only use a manifold
gauge set that features low loss anti−blow back fittings.
See figure 1 for a typical manifold gauge connection setup.

Manifold gauge sets 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 on the high side and a low side of
30" vacuum to 250 psi with dampened speed to 500 psi.
Gauge hoses must be rated for use at up to 800 psi of
pressure with a 4000 psi burst rating.

OPERATING SERVICE VALVES

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.

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

506081−01 09/08

Page 2

OUTDOOR UNIT

(Uncased Coil Shown)

LOW

PRESSURE

GAUGE MANIFOLD

PRESSURE

TO

HFC−410A

DRUM

HIGH

LIQUID LINE

SERVICE VALVE

COMPRESSOR

FILTER DRIER

Figure 1. Typical Manifold Gauge Connection Setup

Each service valve is equipped with a service port which
has a factory−installed valve stem.

1/12 TURN

12

1

2

3

4

7

5

6

9

10

8

11

1/6 TURN

12

1

2

3

4

7

5

6

11

10

9

8

Figure 2. Cap Tightening Distances

IMPORTANT

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

OUTDOOR

COIL

SUCTION LINE
SERVICE VALVE

To Open and Close Angle−Type Service Valve:

TXV OR FIXED
ORIFICE

A valve stem cap protects the valve stem from
contamination and assures a leak−free seal.

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
suction-line valve sizes) to back the stem out
counterclockwise as far as it will go.

3. Replace the stem cap and tighten as follows:

 With Torque Wrench: Finger tighten and then

tighten per table 1.

 Without Torque Wrench: Finger tighten and use an

appropriately sized wrench to turn an additional
1/12 turn clockwise as illustrated in figure 2.

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

NOTE− To prevent stripping of the cap, the appropriately
sized wrench should fit snugly over the cap before
tightening the cap.

Operating Angle−Type Service Valve

To Access Angle−Type 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 to the service port.

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

 With Torque Wrench: Finger tighten and then

tighten per table 1.

 Without Torque Wrench: Finger tighten and use an

appropriately sized wrench to turn an additional
1/6 turn clockwise as illustrated in figure 2.

Page 3

SERVICE PORT CAP

SERVICE PORT

CORE

VALVE STEM

FRONT-SEATED

TO INDOOR

UNIT

TO OUTDOOR UNIT

STEM CAP

Figure 3. Angle−Type Service Valve

(Front−Seated Closed)

SERVICE PORT

(VALVE STEM SHOWN
CLOSED) INSERT HEX
WRENCH HERE

CLOSED TO BOTH INDOOR

AND OUTDOOR UNITS

13ACX SERIES

SERVICE PORT CAP

SERVICE PORT

CORE

TO INDOOR

UNIT

STEM CAP

SERVICE PORT

(VALVE STEM SHOWN OPEN)
INSERT HEX WRENCH HERE

To Open and Close Ball−Type Service Valve:

A valve stem cap protects the valve stem from
contamination and assures a leak−free seal.

1. Remove stem cap with an appropriately sized wrench.

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

3. Replace the stem cap and tighten as follows:

 With Torque Wrench: Finger tighten and then

tighten per table 1.

TO OUTDOOR UNIT

OPEN TO BOTH INDOOR AND

OUTDOOR UNITS

Figure 4. Angle−Type Service Valve

(Back−Seated Opened)

Operating Ball−Type Service Valve

To Access Ball−Type Service Port:

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

OPEN TO LINE SET WHEN VALVE IS CLOSED, TO

BOTH LINE SET AND UNIT WHEN VALVE IS OPEN.

TO OPEN ROTATE STEM
COUNTERCLOCKWISE 90°.

TO CLOSE ROTATE STEM
CLOCKWISE 90°.

SERVICE PORT

SERVICE PORT

CORE

SERVICE PORT CAP

TO OUTDOOR UNIT

TO INDOOR UNIT

BALL (SHOWN
CLOSED)

STEM CAP

VALV E
STEM

 Without Torque Wrench: Finger tighten and use an

appropriately sized wrench to turn an additional
1/12 turn clockwise as illustrated in figure 2.

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

Recovering Refrigerant from Existing
System

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

METHOD 1:

Use this method if the existing outdoor unit is not equipped
with manual shut−off valves, and plan on using existing
HCFC−22 refrigerant to flush the system.

NOTE − Use recovery machine instructions for specific
setup requirements.

Perform the following task:

1. Disconnect all power to the existing outdoor unit.

2. Connect to the existing unit a gauge set, clean
recovery cylinder and a recovery machine. Use the
instructions provided with the recovery machine on
how to setup the connections.

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

RECOVERY MACHINE

MANIFOLD GAUGES

Figure 5. Ball−Type Service Valve

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

2. Connect gauge to the service port.

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

 With Torque Wrench: Finger tighten and then

tighten per table 1.

 Without Torque Wrench: Finger tighten and use an

appropriately sized wrench to turn an additional
1/6 turn clockwise as illustrated in figure 2.

506081−01 09/08

Page 4

CLEAN RECOVERY
CYLINDER

OUTDOOR UNIT

Figure 6. Typical Refrigerant Recovery (Method 1)

METHOD 2:

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

IMPORTANT: Some system configurations may contain
higher than normal refrigerant charge due to either large
internal coil volumes, and/or long line sets. The following
conditions may cause the compressor to stop functioning:

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 cycled 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 suction 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:

1. Start the existing HCFC−22 system in the cooling
mode and close the liquid line valve.

2. Pump as much of the existing HCFC−22 refrigerant
with the compressor back into the outdoor unit until
you have reached the limitations of the outdoor
system. Turn the outdoor unit main power OFF and
use a recovery machine to remove the remaining
refrigerant in the system.

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

3. When the low side system pressures reach 0 psig,
close the suction line valve.

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

Removing Existing Outdoor Unit

Perform the following task at the existing outdoor unit:

 Disconnect line set at the service valves.
 Disconnect electrical service at the disconnect switch.
 Remove old outdoor unit.

Positioning New Outdoor Unit

See Unit Dimensions on page 2 for sizing mounting slab,
platforms or supports. Refer to figure 7 for mandatory
installation clearance requirements.

*

*

*

* SEE NOTES BELOW THIS FIGURE FOR FURTHER DETAILS.

Figure 7. Installation Clearances

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 mm)

.

 Clearance on one of the remaining two sides may be

12 in. (305 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.

POSITIONING CONSIDERATIONS

CAUTION

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 8.

Page 5

13ACX SERIES

INSTALL UNIT AWAY

FROM WINDOWS

TWO 90° ELBOWS INSTALLED

IN LINE SET WILL REDUCE

LINE SET VIBRATION.

Figure 8. 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 9.

DISCHARGE AIR

BUILDING

STRUCTURE

MOUNTING
SLAB

GROUND LEVEL

Figure 9. 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 9.

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 8.

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

Model

−018

−024

−030

−036

−042

−048

−060

Valve Field
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.

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 10. This
filter drier must be installed to ensure a clean,

506081−01 09/08

Page 6

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 8 for
special procedures on brazing filter drier connections to
the liquid line.

OUTSIDE WALL

WOOD BLOCK

BETWEEN STUDS

IMPORTANT - REFRIGERANT LINES

MUST NOT CONTACT WALL.

SUCTION LINE

LIQUID LINE

BRAZE CONNECTION

POINTS

LIQUID

LINE

OUTDOOR

UNIT

LIQUID LINE

SERVICE VALVE

LINE

LIQUID LINE

FILTER DRIER

Figure 10. Typical Liquid Line Filter Drier

Installation

LINE SET ISOLATION

This following illustrations provide best practices on
ensuring proper refrigerant line set isolation:

 Installation of line set on horizontal runs is

illustrated in figure 11.

 Installation of line set on vertical runs is illustrated in

figure 12.

 Installation of a transition from vertical to

horizontal is illustrated in figure 13.

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

SUCTION LINE WRAPPED

WITH ARMAFLEX

IMPORTANT!

REFRIGERANT

LINES MUST NOT

CONTACT

STRUCTURE.

PVC

PIPE

OUTSIDE

WALL

FIBERGLASS

INSULATION

WIRE TIE

INSIDE WALL

STRAP

SLEEVE

WIRE TIE

WOOD BLOCK

WIRE TIE

STRAP

SLEEVE

LIQUID LINE

CAULK

TO HANG LINE SET FROM JOIST OR RAFTER, USE EITHER METAL STRAPPING
MATERIAL OR ANCHORED HEAVY NYLON WIRE TIES.

STRAPPING MATERIAL

(AROUND SUCTION

LINE ONLY)

TAPE OR
WIRE TIE

FLOOR JOIST OR

ROOF RAFTER

8 FEET

FLOOR JOIST OR

ROOF RAFTER

METAL

SLEEVE

STRAP THE SUCTION LINE TO
THE JOIST OR RAFTER AT 8 FEET
INTERVALS THEN STRAP THE
LIQUID LINE TO THE SUCTION
LINE.

8 FEET

WIRE TIE
(AROUND
SUCTION LINE
ONLY)

TAPE OR
WIRE TIE

Figure 11. Refrigerant Line Set: Installing Horizontal

Runs

Figure 12. Refrigerant Line Set: Installing Vertical

Runs (New Construction Shown)

AUTOMOTIVE

STRAP LIQUID LINE
TO SUCTION LINE

LIQUID LINE

SUCTION LINE − WRAPPED
IN ARMAFLEX

ANCHORED HEAVY NYLON
WIRE TIE OR AUTOMOTIVE
MUFFLER-TYPE HANGER

WALL
STUD

METAL SLEEVE

MUFFLER-TYPE HANGER

Figure 13. Refrigerant Line Set: Transition

from Vertical to Horizontal

Page 7

13ACX SERIES

1

2

3

CUT AND DEBUR

7

INSTALL CORE ONLY FOR

BOTH SERVICE PORTS AFTER

THEY HAVE COOLED.

INDOOR UNIT

6

BRAZE LINE SET

REMOVE CAP AND CORE FROM

BOTH LIQUID AND SUCTION

SERVICE PORTS

SERVICE PORT MUST BE

OPEN TO ALLOW EXIT
POINT FOR NITROGEN

SUCTION LINE

LIQUID LINE

Figure 14. Brazing Connections

Brazing Connections

Use the following procedure to braze the line set to the new
air conditioner unit. Figure 14 is provided as a general
guide for preparing to braze the line set to the air
conditioner unit.

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.

WARNING

Danger of fire. Bleeding the
refrigerant charge from only the high
side may result in the low side shell
and suction tubing being
pressurized. Application of a brazing
torch while pressurized may result in
ignition of the refrigerant and oil
mixture − check the high and low
pressures before un−brazing.

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).

ATTACH

GAUGES

SERVICE

5

VALVE

SERVICE

VALVE

OUTDOOR

UNIT

FLOW NITROGEN

NITROGEN

4

WRAP

SERVICE

VALV E

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.

Use the following procedure to braze the line set to the new
air conditioner unit. Figure 14 is provided as a general
guide for preparing to braze the line set to the air
conditioner unit.

1. Cut ends of the refrigerant lines square (free from
nicks or dents). Debur the ends. The pipe must remain
round, do not pinch end of the line.

2. Remove service cap and core from both the suction
and liquid line service ports.

3. Connect gauge low pressure side to liquid line service
valve.

4. To protect components during 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.

5. 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 suction service
valve. The TXV metering device at the indoor unit coil
will allow low pressure nitrogen to flow through the
system.)

506081−01 09/08

Page 8

NOTE − The fixed orifice or TXV metering device at the
indoor unit will allow low pressure nitrogen to flow through
the system.)

TYPICAL FIXED ORIFICE REMOVAL PROCEDURE

DISTRIBUTOR TUBES

LIQUID LINE ORIFICE HOUSING

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

6. Braze the liquid line to the liquid line service valve.
Turn off nitrogen flow.

IMPORTANT

Repeat procedure starting at paragraph 4 for brazing the
suction line to service port valve.

7. After all connections have been brazed, disconnect
manifold gauge set the from service ports and remove
wrapping. Reinstall the service port core for both of the
outdoor unit’s service valves.

Removing Indoor Unit Metering Device

Remove the existing HCFC−22 fixed orifice or TXV from
the indoor coil. The existing indoor unit HCFC−22 metering
device is not approved for use with HFC−410A refrigerant
and may prevent proper flushing.

REPLACEMENT PARTS

If replacement parts are necessary for the indoor unit,
order catalog number 69J46 (LB−95325A). The kit includes
the following:

LIQUID LINE ORIFICE HOUSINGS (10)

TEFLON RINGS (20)

LIQUID LINE ASSEMBLIES

(INCLUDES STRAINER) (10)

BRASS NUTS (10)

Figure 15. Kit 69J46 Components

LIQUID LINE

ASSEMBLY

PISTON
RETAINER

STRAINER

COPPER
TUBE

VALVE STEM

TEFLON RING

FIXED
ORIFICE

VALVE STEM CAP

REMOVE AND DISCARD
VALVE STEM ASSEMBLY
(IF PRESENT)

BRASS NUT

LIQUID LINE ASSEMBLY

(INCLUDES STRAINER)

(Uncased Coil Shown)

Figure 16. Typical Fixed Orifice Removal

1. On fully cased coils, remove the coil access and
plumbing panels.

2. Remove any shipping clamps holding the liquid line
and distributor assembly.

3. Using two wrenches, disconnect liquid line from liquid
line orifice housing. Take care not to twist or damage
distributor tubes during this process.

4. Remove and discard fixed orifice, valve stem
assembly if present and Teflon ring as illustrated in
figure 16.

5. Use a field−provided fitting to temporary reconnect the
liquid line to the indoor unit’s liquid line orifice housing.

TYPICAL TXV REMOVAL PROCEDURE

1. On fully cased coils, remove the coil access and
plumbing panels.

2. Remove any shipping clamps holding the liquid line
and distributor assembly.

3. Disconnect the equalizer line from the TXV equalizer
line fitting on the suction line.

4. Remove the suction line sensing bulb as illustrated in
figure 17.

5. Disconnect the liquid line from the TXV at the liquid line
assembly.

6. Disconnect the TXV from the liquid line orifice housing.
Take care not to twist or damage distributor tubes
during this process.

7. Remove and discard the TXV along with the two Teflon
rings.

Page 9

13ACX SERIES

TWO PIECE

PATCH PLATE

(UNCASED COIL

ONLY)

DISTRIBUTOR

ASSEMBLY

MALE EQUALIZER

LINE FITTING

LIQUID LINE

ORIFICE

HOUSING

EQUALIZER
LINE

SENSING

STUB END

TEFLON
RING

LIQUID LINE ASSEMBLY

BULB

SUCTION

LINE

TXV

WITH BRASS NUT

TEFLON

RING

SENSING

LINE

LIQUID

LINE

Figure 17. Typical TXV Removal

8. Use a field−provided fitting to temporary reconnect the
liquid line to the liquid line orifice housing.

(Uncased Coil Shown)

If the original system used:

 HCFC−22 refrigerant, then flush the system using the

procedure provided in this section.

 HFC−410A refrigerant, then proceed to Installing New

Refrigerant Metering Device.

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

SUCTION LINE

SERVICE VALVE

EXISTING

INDOOR

UNIT

LIQUID LINE SERVICE VALVE

RECOVERY

CYLINDER

SUCTION

LIQUID

NOTE − The inverted HCFC−22 cylinder must contain at least the same
amount of refrigerant as was recovered from the existing system.

NEW

OUTDOOR

UNIT

OPENED

RECOVERY MACHINE

Figure 18. Typical Flushing Connection

MANIFOLD

LOW

PRESSURE

TANK
RETURN

INLET

DISCHARGE

GAUGE

PRESSURE

HIGH

CLOSED

Flushing the System

IMPORTANT

The line set and indoor unit coil must be flushed
with at least the same amount of clean refrigerant
that previously charged the system. Check the
charge in the flushing cylinder before proceeding.

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.

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.

506081−01 09/08

CAUTION

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

REQUIRED EQUIPMENT

Equipment required to flush the existing line set and indoor
unit coil:

 Two clean HCFC−22 recovery bottles,
 Oilless recovery machine with pump-down feature,
 Two gauge sets (one for HCFC−22; one for

HFC−410A).

FLUSHING PROCEDURE

1. Connect the following:

 HCFC−22 cylinder with clean refrigerant to the

suction service valve,

 HCFC−22 gauge set to the liquid line valve,
 Recovery machine with an empty recovery tank to

the gauge set.

2. Set the recovery machine for liquid recovery and start
the recovery 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.

3. Invert the cylinder of clean and open its valve to allow
liquid refrigerant to flow into the system through the
suction 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.

4. After all of the liquid refrigerant has been recovered,
switch the recovery machine to suction recovery so
that all of the suction is recovered. Allow the recovery
machine to pull a vacuum on the system.

Page 10

5. Close the valve on the inverted drum and the gauge
set valves. Pump the remaining refrigerant out of the
recovery machine and turn the machine off.

6. Use dry nitrogen to break the vacuum on the
refrigerant lines and indoor unit coil before removing
the recovery machine, gauges and refrigerant drum.

Installing New Indoor Unit Metering
Device

13ACX units can be configured for use in with HFC−410A
fixed orifice or TXV metering devices. This section
provides instructions on installing either a fixed orifice or
TXV refrigerant metering device.

1/8 TURN

12

11

8

7

6

9

10

8

11

12

1

2

3

10

9

4

7

5

6

Figure 19. Tightening Distance

13ACX ENGINEERING HANDBOOK

See the 13ACX Engineering Handbook for approved
indoor/outdoor match−ups, applicable fixed orifice and
TXV kits, and application information.

Figures 20 and 21 illustrates the typical RFC and TXV kit
parts and quantities.

FIXED ORIFICE (1)

FIXED ORIFICE EXTRACTOR (1)

TEFLON RING (1)

FIXED ORIFICE STICKER (1)

Figure 20. Fixed Orifice Kit Components

1/2 TURN

1

2

3

4

5

TXV (1)

HEX HEAD BOLTS

AND NUTS (2)

TEFLON
RINGS (2)

COPPER

MOUNTING

STRAP (1)

Figure 21. TXV Kit Components

TYPICAL FIXED ORIFICE INSTALLATION
PROCEDURE

LIQUID LINE ORIFICE HOUSING

FIXED

ORIFICE

TEFLON

RING

LIQUID

LINE

(Uncased Coil

Shown)

LIQUID LINE ASSEMBLY

WITH BRASS NUT

Figure 22. Typical Fixed Orifice Installation

1. Remove the field−provided fitting that temporary
reconnected the liquid line to the indoor unit’s liquid
line orifice housing.

2. Ensure that the fixed orifice supplied with the outdoor
unit is installed with the nylon seat pointing toward the
liquid line orifice housing.

3. Apply a small amount of refrigerant oil on the Teflon
ring and insert securely into the liquid line orifice
housing.

4. Attached the liquid line assembly 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 figure 19, or 20 ft−lb.

5. Place the supplied fixed orifice sticker on the indoor
cabinet after installation.

TYPICAL TXV INSTALLATION PROCEDURE

The TXV unit can be installed internal or external to the
indoor coil. In applications where an uncased coil is being
installed in a field−provided plenum, install the TXV in a
manner that will provide access for field servicing of the
TXV. Refer to Figure 23 for reference during installation of
TXV unit.

Page 11

13ACX SERIES

TWO PIECE

PATCH PLATE

(UNCASED COIL

ONLY)

DISTRIBUTOR

TUBES

(Uncased Coil Shown)

LIQUID LINE

ORIFICE

HOUSING

STUB END

TXV

TEFLON

RING

NOTE − Insulating the sensing bulb once installed may be
required when the bulb location is external to the coil
casing.

ON LINES SMALLER THAN 7/8",

SUCTION LINE

MOUNT SENSING BULB AT
EITHER THE 3 OR 9 O’CLOCK

POSITION.

TEFLON

DISTRIBUTOR

ASSEMBLY

MALE EQUALIZER LINE

FITTING (SEE FIGURE 25
FOR FURTHER DETAILS)

SENSING BULB INSULATION IS
REQUIRED IF MOUNTED EXTERNAL
TO THE COIL CASING. SEE FIGURE 24
FOR BULB POSITIONING.

EQUALIZER
LINE

RING

LIQUID LINE ASSEMBLY

WITH BRASS NUT

SUCTION

LINE

SENSING

LINE

LIQUID

LINE

Figure 23. Typical TXV Installation

To prevent any possibility of water damage, properly
insulate all parts of the TXV assembly that may sweat due
to temperature differences between the valve and its
surrounding ambient temperatures.

1. Remove the field−provided fitting that temporary
reconnected the liquid line to the indoor unit’s liquid
line orifice housing.

2. Install one of the provided Teflon rings around the
stubbed end of the TXV and lightly lubricate the
connector threads and expose surface of the Teflon
ring with refrigerant oil.

3. Attach the stubbed end of the kit 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 figure 19, or 20 ft−lb.

4. Place the remaining Teflon ring around the other end
of the TXV. Lightly lubricate connector threads and
expose surface of the Teflon ring with refrigerant oil.

5. Attach the liquid line assembly to the TXV. Finger
tighten and use an appropriately sized wrench to turn
an additional 1/22 turn clockwise as illustrated in figure
19, or 20 ft−lb.

6. Attach the suction line sensing bulb in the proper
orientation as illustrated in figure 24 using the copper
mounting strap and fastening hardware provided.

BULB

SUCTION LINE

BULB

12

12

BULB

ON 7/8" AND LARGER LINES,
MOUNT SENSING BULB AT
EITHER THE 4 OR 8 O’CLOCK
POSITION. NEVER MOUNT ON
BOTTOM OF LINE.

BULB

NOTE − Never mount on
bottom of line.

Figure 24. TXV Sensing Bulb Installation

7. Remove and discard either the flare seal cap or flare
nut with copper flare seal bonnet from the equalizer
line port on the suction line as illustrated in figure 25.

IMPORTANT

When removing the flare nut, ensure that the copper
flare seal bonnet is removed.

FLARE SEAL

CAP

OR

MALE BRASS EQUALIZER

Figure 25. Copper Flare Seal Bonnet Removal

8. Connect the equalizer line from the TXV to the
equalizer suction port on the suction line. Finger
tighten the flare nut plus 1/8 turn (7 ft−lbs) as illustrated
in figure 19.

FLARE NUT

COPPER

FLARE SEAL

BONNET

LINE FITTING

SUCTION LINE

506081−01 09/08

Page 12

Testing for Leaks

After the line set has been connected to both the indoor
and outdoor units, check the line set connections at both
the indoor and outdoor units for leaks. Use the following
procedure to test for leaks:

IMPORTANT

Leak detector must be capable of sensing HFC
refrigerant.

6. 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.

NOTE − Amounts of refrigerant will vary with line lengths.

7. Check all joints for leaks.

8. Purge dry nitrogen and HFC−410A mixture.

9. Correct any leaks and recheck.

10. After leak testing disconnect gauges from service
ports.

Evacuating the System

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.

WARNING

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.

1. Connect an HFC−410A manifold gauge set high
pressure hose to the suction valve service port.

NOTE − Normally, the high pressure hose is connected to
the liquid line port; however, connecting it to the suction
port better protects the manifold gauge set from high
pressure damage.

2. 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 (suction only).

3. 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.

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

5. 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.

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.

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.

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.

1. Connect manifold gauge set to the service valve ports
as follows:

 low pressure gauge to suction line service valve

 high pressure gauge to liquid line service valve

2. Connect micron gauge.

3. Connect the vacuum pump (with vacuum gauge) to
the center port of the manifold gauge set.

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

5. 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 to
determine if there is a rapid rise in sure 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.

6. 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

Page 13

13ACX SERIES

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.

7. 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.

WIRE TIES

GROMMET

HIGH VOLTAGE
FIELD WIRING

LOW VOLTAGE
FIELD WIRING

FACTORY
WIRING

8. 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.

9. 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
valves to break the vacuum from 1 to 2 psig positive
pressure in the line set and indoor unit. Close manifold
gauge valves and shut off the HFC−410A cylinder and
remove the manifold gauge set.

Servicing Unit Delivered Void of Charge

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

1. Use nitrogen to pressurize the system and check for
leaks. Repair all leaks.

2. Evacuate the system to remove as much of the
moisture as possible.

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

4. Evacuate the system again. Then, weigh the
appropriate amount of HFC−410A refrigerant as listed
on unit nameplate into the system.

5. Monitor the system to determine the amount of
moisture remaining in the oil. It may be necessary to
replace the liquid line filter drier several times to
achieve the required dryness level. If system

dryness is not verified, the compressor will fail in
the future.

Electrical Connections

In the United States, 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 blower coil installation instructions for
additional wiring application diagrams and refer to unit
nameplate for minimum circuit ampacity and maximum
over−current protection size.

506081−01 09/08

Page 14

Figure 26. Separating High/Low Voltage Field Wiring

(Typical Field Wiring)

WARNING

Electric Shock Hazard. Can cause
injury or death.

Line voltage is present at all
components on units with single-pole
contactors, even when unit is not in
operation!

Unit may have multiple power
supplies. Disconnect all remote
electric power supplies before
opening access panel.

Unit must be grounded in accordance
with national and local codes.

WIRING CONNECTIONS

1. Install line voltage power supply to unit from a properly
sized disconnect switch. Any excess high voltage field
wiring should be trimmed or secured away from the
low voltage field wiring as illustrated in figure 28.

2. Ground unit at unit disconnect switch or to an earth
ground.

3. Connect conduit to the unit using provided conduit
bushing.

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

NOTE − For proper voltages, select thermostat wire gauge
per the following chart:

Table 3. Wire Run Lengths

Wire Run Length AWG # Insulation Type

less than 100’ (30m) 18

more than 100’ (30m) 16

5. Install low−voltage wiring from outdoor to indoor unit
and from thermostat to indoor unit.

6. Do not bundle any excess 24V control wire inside
control box. Run control wire through installed wire tie
and tighten wire tie to provided low voltage strain relief
and to maintain separation of field installed low and
high voltage circuits.

NOTE − 24VAC, Class II circuit connections are made in
the low voltage junction box

Color−coded, temperature
rating 35ºC minimum.

Figure 27. Typical 13ACX Unit Wiring Diagram

THERMOSTAT INDOOR UNIT

W1

G

C

R

Y

POWER

HEAT

COOLING

INDOOR

BLOWER

COMMON

R

W

Y

G

C

OUTDOOR

UNIT

Y1

C

Figure 28. 24VAC Control Wiring Diagrams

(Field Installed)

NOTE − To facilitate conduit, a hole is in the bottom of the
control box. Connect conduit to the control box using a
proper conduit fitting.

NOTE − Units are approved for use only with copper
conductors.

NOTE − See unit wiring diagram for power supply
connections. If indoor unit is not equipped with blower
relay. It must be field−provided and installed (P−8−3251 or
equivalent)

Start−Up and Charging Procedures

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.

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.

Page 15

13ACX SERIES

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.

SETTING UP TO CHECK CHARGE

1. Close manifold gauge set valves. Connect the center
manifold hose to an upright cylinder of HFC−410A.

2. Connect the manifold gauge set to the unit’s service
ports as illustrated in figure 1.

 low pressure gauge to suction line service port

 high pressure gauge to liquid line service port

INDOOR AIRFLOW CHECK

Check airflow using the Delta−T (DT) process using the
illustration in figure 29.

8. Check system for sufficient refrigerate by using the
procedures listed under Testing and Charging
System.

Temp.
of air
entering
indoor
coil ºF

A

Wet−bulb ºF

53º

DRY

BULB

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
74 21 21 21 20 19 19 18 17 16 16 15 14 13 12

Dry−bulb

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

T

C

Drop

19º

All temperatures are
expressed in ºF

DT

air flowair flow

INDOOR
COIL

B

A

72º

B

64º

WET

BULB

DRY

BULB

Figure 29. Checking Indoor Airflow over Evaporator Coil using Delta−T (DT) Chart

START: Determine how refrigerant is metered

DETERMINING CHARGE METHOD

Use the illustration in figure 30 to determine the correct
charging method.

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
justment is needed. See examples: Assume DT = 15 and A temp. =
72º, these C temperatures would necessitate stated actions:

Cº T

Drop

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

4. Adjust the fan speedSee indoor unit instructions to in-

crease/decrease fan speed.

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

) = A minus C.

Drop

and the desired DT (T

Drop

– DT = ºF ACTION

Drop

–DT) is within +3º, no ad-

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)

 Manifold gauge set connected to unit
 Thermometers:

− to measure outdoor ambient
temperature

− to measure liquid line temperature

− to measure suction line
temperature

506081−01 09/08

TXV

Which

metering

device?

65ºF

(18.3ºC) and

Above

APPROACH OR

64ºF

(17.7ºC) and

Below

WEIGH-IN

SUBCOOLING

Figure 30. Determining Charge Method

Page 16

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

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 31. HFC−410A Weigh In TXV Method

ABOVE or

BELOW

64ºF and

BELOW

1. Check Liquid and suction line pressures

2. Compare unit pressures with Table 4,
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.

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

64ºF and

BELOW

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

If value is LESS
than shown, add
refrigerant.

If value is MORE
than shown, remove
refrigerant.

MORE or

LESS

Figure 32. HFC−410A Approach TXV Charge

ABOVE or

BELOW

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

and

ABOVE

1. Confirm proper airflow across coil using figure

29.

2. Compare unit pressures with Table 4, 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.

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

Page 17

13ACX SERIES

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)

64ºF and

ABOVE or

BELOW

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

If value is LESS
than shown, add
refrigerant.

If value is MORE
than shown, remove
refrigerant.

MORE or

LESS

1. Confirm proper airflow across coil using figure

65ºF

and

ABOVE

29.

2. Compare unit pressures with Table 4, 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 5):

SATº = ______

10. Subtract to determine subcooling (SCº):

SATº_____ − LIQº _____ = SCº _____

11. Compare results with table below.

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

Figure 33. HFC−410A Subcooling TXV Charge

START: Measure outdoor ambient temperature

USE SUPERHEAT

40ºF

and

ABOVE

WEIGH IN RFC

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 34. HFC−410A Weigh In RFC Method

ABOVE or

BELOW

39ºF and

BELOW

1. Check Liquid and suction line pressures

2. Compare unit pressures with Table 4,
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.

506081−01 09/08

Page 18

START: Measure outdoor ambient temperature

USE WEIGH-IN METHOD

Weigh-in or remove refrigerant
based upon line length

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

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

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

39ºF and

BELOW

SHº (Superheat) Values (+/−5ºF)

Wet Bulb (air entering indoor coil)

ABOVE or

BELOW

40ºF

and

ABOVE

1. Confirm proper airflow across coil using figure 29.

2. Compare unit pressures with Table 4, 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

5):

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.

MORE or

LESS

If value is MORE
than shown, then

ADD refrigerant.

Figure 35. HFC−410A Superheat RFC Method

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

Page 19

13ACX SERIES

Table 4. HFC−410A Normal Operating Pressures (Liquid +10 and Suction +5 psig)

IMPORTANT

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. 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

506081−01 09/08

Page 20

Table 5. HFC−410A Temperature (°F) − Pressure (Psig)

°F Psig °F Psig °F Psig °F Psig °F Psig °F Psig °F Psig °F Psig

32 100.8 48 137.1 63 178.5 79 231.6 94 290.8 110 365.0

125 445.9

141 545.6
33 102.9 49 139.6 64 181.6 80 235.3 95 295.1 111 370.0 126 451.8 142 552.3
34 105.0 50 142.2 65 184.3 81 239.0 96 299.4 112 375.1 127 457.6 143 559.1
35 107.1 51 144.8 66 187.7 82 242.7 97 303.8 113 380.2 128 463.5 144 565.9
36 109.2 52 147.4 67 190.9 83 246.5 98 308.2 114 385.4 129 469.5 145 572.8
37 111.4 53 150.1 68 194.1 84 250.3 99 312.7 115 390.7 130 475.6 146 579.8
38 113.6 54 152.8 69 197.3 85 254.1 100 317.2 11 6 396.0 131 481.6 147 586.8
39 115.8 55 155.5 70 200.6 86 258.0 101 321.8 11 7 401.3 132 487.8 148 593.8
40 118.0 56 158.2 71 203.9 87 262.0 102 326.4 11 8 406.7 133 494.0 149 601.0
41 120.3 57 161.0 72 207.2 88 266.0 103 331.0 119 412.2 134 500.2 150 608.1
42 122.6 58 163.9 73 210.6 89 270.0 104 335.7 120 417.7 135 506.5 151 615.4
43 125.0 59 166.7 74 214.0 90 274.1 105 340.5 121 423.2 136 512.9 152 622.7
44 127.3 60 169.6 75 217.4 91 278.2 106 345.3 122 428.8 137 519.3 153 630.1
45 129.7 61 172.6 76 220.9 92 282.3 107 350.1 123 434.5 138 525.8 154 637.5
46 132.2 62 175.4 77 224.4 93 286.5 108 355.0 124 440.2 139 532.4 155 645.0

47 134.6 78 228.0 109 360.0 140 539.0

INSTALLING SERVICE VALVE CAPS

Disconnect gauge set and re−install both the liquid and
suction service valve caps.

OUTDOOR UNIT

SERVICE VALVES

INSTALL CAPS

Figure 36. Installing Service Valve Caps

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 37. The switch is a Single Pole, Single Throw
(SPST), manual−reset switch with red cap that is normally
closed and removes power from the compressor when
discharge pressure rises above factory setting at 590 + 10
psi.

HIGH PRESSURE

SWITCH

LIQUID LINE

SERVICE VALVE

Figure 37. High Pressure Switch Location

SUCTION LINE
SERVICE VALVE

Page 21

13ACX SERIES

Maintenance

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.

At the beginning of each cooling season, the system
should be checked as follows:

OUTDOOR UNIT

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

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

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

4. Check all wiring for loose connections.

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

6. Check amperage draw on outdoor fan motor.

UNIT NAMEPLATE: _________ ACTUAL: __________

5. Check all wiring for loose connections.

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

7. Check amperage draw on blower motor.

UNIT NAMEPLATE: _________ ACTUAL: __________

Homeowner Information

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.

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.

NOTE − A white residue may appear on the coil guards and
grilles on outdoor units. The residue is a non−toxic
byproduct of manufacturing the flexible coating. It can be
removed by wiping the coil guard with a cloth.

9 PINS USED ON −048
AND −060; 6 PINS ALL
OTHERS

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

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

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.

INDOOR UNIT

1. Clean or change filters.

2. Blower motors are pre−lubricated 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 cubic
feet per minute (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.

PUSH PIN

MESH

SCREEN

Figure 38. Cleaning debris from mesh

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:

506081−01 09/08

Page 22

1. Make sure power is off before cleaning. Clean and
inspect outdoor coil. The coil may be flushed with a
water hose.

2. The outdoor coil is protected by an inner mesh screen
and a wire cage (see figure 38). If debris has collected
between the mesh screen and the coil and cannot be
dislodged by spraying un−pressurized water from
inside coil surface to the outside, the mesh may be
removed by first removing the top of the unit which will
allow for removal of the wire cage.

3. Then, using pliers to grip the head of the push pins, pull
straight out to extract the push pins along one side of
the coil. If necessary, remove the push pins along the
back of the unit; it is usually unnecessary to fully
remove the inner mesh screen.

4. Drape the mesh screen back and wash the coil. When
all the debris has been removed from the coil, reinstall
the mesh screen by positioning it in its original position
and reinserting the push pin. No tool is required to
push the pin back into the same slot in the fins.

5. If the push pin is loose and tends not to stay in place,
brush the fins with a fin brush (22 fins/in). Line up the
push pin a couple fins to the right or left of the original
hole and re−insert the pin.

PRESERVICE CHECK

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

 Make sure all electrical disconnect switches are ON.
 Make sure the room thermostat temperature selector

AND the system switch are properly set.

 Replace any blown fuses, or reset circuit breakers.
 Make sure unit access panels are in place.
 Make sure air filter is clean.
 Locate and record unit model number before calling.

PROGRAMMABLE THERMOSTATS

Your Lennox system may be controlled by a
programmable thermostat. These thermostats provide the
added feature of programmable time-of-day set points for
both heating and cooling. Refer to the user’s information
manual provided with your thermostat for operation
details.

THERMOSTAT OPERATION

Thermostat operations vary from one thermostat to
another. The following provides general operation
procedures. Refer to the user’s information manual
provided with your thermostat for specific operation
details.

Temperature
Setting Levers

Fan Switch In AUTO or INT (intermittent) mode, the blower

System Switch Set the system switch for heating, cooling or auto

Temperature
Indicator

Set the lever or dial to the desired temperature
setpoints for both heating and cooling. Avoid
frequent temperature adjustment; turning the unit
offthen back onbefore pressures can equalize
will put unusual stress on the unit’s compressor.

operates only when the thermostat calls for heating
or cooling. This mode is generally preferred when
humidity control is a priority. The ON or CONT
mode provides continuous indoor blower
operation, regardless of whether the compressor
or furnace is operating. This mode is required when
constant air circulation or filtering is desired.

operation. The auto mode allows the system to
automatically switch from heating mode to cooling
mode to maintain predetermined comfort settings.

The temperature indicator displays the actual room
temperature.

Optional Accessories

Refer to the Lennox 13ACX Engineering Handbook for the
latest available accessories for this unit. Below is a list of
accessories available at the time this instruction was
publish.

 Compressor Start Kit

 Loss of Charge Kit

 Low Ambient Kit

 Timed Off Control

 Sound Cover

 Replacement Liquid Line Drier

 Plastic Feet Kit

 Crankcase Heater

Page 23

13ACX SERIES

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? 

506081−01 09/08

Page 24