Lennox XP25-024-230-01, XP25-036-230-01, XP25-048-230-01, XP25-060-230-01 Installation And Service Procedure

INSTALLATION AND SERVICE

PROCEDURE

Service Literature

July 24, 2013 (Revised on Dec. 11, 2014)

Dave Lennox Signature

Corp. 1252-L11

IMPORTANT

This unit has refrigerant piping requirements that are
unique to this this model. Size and install the refrigerant
piping per table 2 (page 14) to ensure proper unit operation.

IMPORTANT: Before applying any power (main, solar or low
voltage) to the outdoor unit, confirm iComfort Wi-Fi
has Version 2.1 or higher software. (Reference iComfort Wi-Fi
thermostat manual.)

This unit is an integral component of a system that requires an
iComfort Wi-Fi
or furnace.

XP25 Heat

Pump

®

thermostat and iComfort®-enabled air handler

iComfort Wi-Fi

Thermostat

iComfort

™

-enabled

air handler or

furnace

®

thermostat

®

®

®

Collection XP25 Series Units

TABLE OF CONTENTS

I. OVERVIEW

Model Number Identification 2....................

Typical Serial Number Identification 2..............

Specifications 2.................................

Electrical Data 3................................

Unit Dimensions 4..............................

Typical Unit Parts Arrangement 5.................

General 7......................................

Operating Service Valves 7.......................

II. INSTALLATION

Unit Placement 9...............................

Removing and Installing Panels 12.................

New or Replacement Line Set 13..................

Brazing Connections 16...........................

Flushing the System 19...........................

Leak Testing the System 21.......................

Evacuating the System 21.........................

Electrical 24.....................................

Servicing Unit Delivered Void of Charge 29..........

Unit Start-Up 29.................................

III. SYSTEM OPERATION AND SERVICE

7-Segment Alert and System Status Codes 30.......

Outdoor Control Push-Button Operation 38..........

Configuring Unit 42...............................

Reconfiguring Outdoor Control using iComfort Wi-Fi

Thermostat 43...................................

System Overview 43.............................

Diagnostic Information 43.........................

Defrost Function 43..............................

Outdoor Temperature Operational Range 44.........

Maintenance 45..................................

SunSource

Unit Wiring Diagrams 46..........................

Factory Wiring Diagrams 49.......................

Unit Sequence of Operations 51...................

Component Testing 56............................

System Refrigerant 85............................

®

Home Energy System 45..............

XP25

®

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.

Page 1

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.

2013 Lennox Industries Inc.

Model Number identification

I. OVERVIEW

X

Refrigerant Type

X = R-410A

Unit Type

P = Heat Pump

230 -02P 25 XXX- -

Minor Revision Number

Voltage

230 = 208/230V-1ph-60hz

Nominal Cooling Capacity

024 = 2 tons

Series

036 = 3 tons
048 = 4 tons
060 = 5 tons

Typical Serial Number Identification

Location Code

19 = Saltillo, Mexico

58 = Marshalltown, IA

Year Code

08 = 2008
09 = 2009
10 = 2010

09 C

8

5

05716

5 (or 6) Digit Unique Number

Month Code

A = January
B = February
C = March

Specifications

Unit Outdoor Fan

Model Number

XP25-024-230-01 68 58 11 lbs., 5 oz. 3 26

Sound Rating Number (dB)

Maximum Minimum

1

Factory Refrigerant

Charge

2

Number of Blades Diameter - inches.

Unit Outdoor Fan

Model Number

XP25-036-230-01 73 58 11 lbs., 8 oz. 3 26

Model Number

XP25-048-230-01 74 64 13 lbs., 14 oz. 3 26

Model Number

XP25-060-230-01 74 64 13 lbs., 0 oz. 3 26

1

Tested according to AHRI Standard 270-2008 test conditions.

2

Factory charge is sufficient for refrigerant line lengths up to 15 feet.

Sound Rating Number (dB)

Maximum Minimum

Sound Rating Number (dB)

Maximum Minimum

Sound Rating Number (dB)

Maximum Minimum

1

Unit Outdoor Fan

1

Unit Outdoor Fan

1

Factory Refrigerant

Factory Refrigerant

Factory Refrigerant

Charge

Charge

Charge

2

2

2

Number of Blades Diameter - inches.

Number of Blades Diameter - inches.

Number of Blades Diameter - inches.

Page 2

XP25

Electrical Data

208/230V-60 Hz-1 Ph

Unit Compressor Outdoor Fan (RPM varies with compressor RPM)

Model Number

Over-

current

Protection

(amps)

1

Minimum

Circuity

Ampacity

Maximum

XP25-024-230-01 25 15.7 10.30 18.00 1/3 2580 1845 723 515 70 32 2.80

Unit Compressor Outdoor Fan (RPM varies with compressor RPM)

Model Number

Over-

current

Protection

(amps)

1

Minimum

Circuity

Ampacity

Maximum

XP25-036-230-01 25 20.3 14.00 18.00 1/3 4130 1865 850 390 214 40 2.80

Unit Compressor Outdoor Fan (RPM varies with compressor RPM)

Model Number

Over-

current

Protection

(amps)

1

Minimum

Circuity

Ampacity

Maximum

XP25-048-230-01 40 33.7 24.70 29.00 1/3 4040 3315 805 658 172 98 2.80

Rated

Load

Amps

2

(RLA)

Locked

Rotor
Amps

(LRA)

Motor

HP

CFM RPM WATTS

MAX MIN MAX MIN MAX MIN

Full

Load
Amps
(FLA)

208/230V-60 Hz-1 Ph

Rated

Load

Amps

2

(RLA)

Locked

Rotor
Amps
(LRA)

Motor

HP

CFM RPM WATTS

MAX MIN MAX MIN MAX MIN

Full

Load
Amps
(FLA)

208/230V-60 Hz-1 Ph

Rated

Load

Amps

2

(RLA)

Locked

Rotor
Amps
(LRA)

Motor

HP

CFM RPM WATTS

MAX MIN MAX MIN MAX MIN

Full

Load
Amps
(FLA)

208/230V-60 Hz-1 Ph

Unit Compressor Outdoor Fan (RPM varies with compressor RPM)

Model Number

Maximum

Over-

current

Protection

(amps)

1

Minimum

Circuity

Ampacity

Rated

Load

Amps

2

(RLA)

Locked

Rotor
Amps
(LRA)

Motor

HP

CFM RPM WATTS

MAX MIN MAX MIN MAX MIN

Load
Amps
(FLA)

XP25-060-230-01 40 34.9 25.70 29.00 1/3 4240 3025 845 600 198 76 2.80

1

HACR type circuit breaker or fuse.

2

Refer to National or Canadian Electrical Code manual to determine wire, fuse and disconnect size requirements.

Full

Page 3

XP25

Unit Dimensions -- Inches (mm)

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.

UNIT SUPPORT

16-7/8

(429)

8-3/4
(222)

3-1/8

(79)

FEET

30-3/4

(781)

26-7/8

(683)

3-3/4 (95)

4-5/8
(117)

BASE WITH ELONGATED LEGS

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 nearby these areas during installation or while
servicing this equipment.

WARNING

Electrical Hazard

High Voltage

Wait 5 Minutes

Electrical components may hold charge. Do
not remove this panel or service this area for
5 minutes after the power has been
removed.

XP25

Page 4

Typical Unit Parts Arrangement

GROUND LUGS

CONTROL PANEL FOR

XP25-024 AND -036

CONTACTOR-SPST

(25FLA/35RES)

INVERTER REACTOR,

GROUND LUGS

230V, 4KW

OUTDOOR

CONTROL

CONTROL PANEL FOR

XP25-048 AND -060

VARIABLE-CAPACITY
INVERTER CONTROL

INVERTER NOISE FILTER FOR
6KW INVERTER (208/240V, 60HZ,
CURRENT RANGE 30A MAXIMUM,
INDUCTANCE 4.3MH

CONTACTOR-SPST

(35FLA/40RES)

OUTDOOR CONTROL

Figure 1. Control Panel Components

Page 5

INVERTER REACTOR,

230V, 6KW

VARIABLE-CAPACITY
INVERTER CONTROL

XP25

VAPOR VALVE

AND GAUGE

PORT

LIQUID VALVE AND

GAUGE PORT

Typical Plumbing Components (-024 and -048)

COMPRESSOR TOP CAP

SWITCH (THERMAL)

MUFFLER

REVERSING

VALV E

VARIABLE-CAPACITY
COMPRESSOR SPEED - HFC-410A,
3-PHASE

CHARGE
C0MPENSATOR
(INTERNAL VOLUME

30.0 CUBIC INCHES)

CHECK EXPANSION
VALVE - (HFC-410A)

HR1 CRANKCASE
HEATER (40W, 240VAC)

TRUE SUCTION LINE

LIQUID LINE SENSOR

LIQUID LINE BI-FLOW

LOW PRESSURE SWITCH - NORMALLY OPEN, SWITCH CLOSES

PORT

FILTER DRIER

(HFC-410A)

WHEN SYSTEM PRESSURES GO ABOVE 40±5 PSIG. OPENS

WHEN SYSTEM PRESSURES GO BELOW 25±5 PSIG

Typical Plumbing Components (-036 and -060)

COMPRESSOR TOP CAP SWITCH (THERMAL)

DISCHARGE LINE

MUFFLER

REVERSING

VALV E

VAPOR VALVE

AND GAUGE

PORT

EXPANSION VALVE SENSING
BULB

CRANKCASE HEATER
THERMOSTAT (S40) OPENS AT
70ºF, CLOSES AT 50ºF

HIGH PRESSURE SWITCH - NORMALLY CLOSED, SWITCH OPENS
WHEN SYSTEM PRESSURES REACH 590+
WHEN PRESSURES DROP BELOW 418+

15 PSIG, CLOSES

15 PSIG

VARIABLE-CAPACITY
COMPRESSOR SPEED - HFC-410A,
60HZ, 3-PHASE

CHECK EXPANSION
VALVE - (HFC-410A)

LIQUID VALVE AND

GAUGE PORT

TRUE SUCTION LINE

LIQUID LINE SENSOR

LIQUID LINE BI-FLOW

LOW PRESSURE SWITCH - NORMALLY OPEN, SWITCH CLOSES

PORT

FILTER DRIER

WHEN SYSTEM PRESSURES GO ABOVE 40±5 PSIG. OPENS

WHEN SYSTEM PRESSURES DROP BELOW 25±5 PSIG

Figure 2. Plumbing (Component Locations and Specifications)

HR1 CRANKCASE HEATER (40W,
240VAC)

CRANKCASE HEATER THERMOSTAT

CHECK EXPANSION VALVE SENSING BLUB

HIGH PRESSURE SWITCH - NORMALLY CLOSED, SWITCH
OPENS WHEN SYSTEM PRESSURES REACH 590+
CLOSES WHEN PRESSURES DROP BELOW 418+

Page 6

15 PSIG,

15 PSIG

XP25

IMPORTANT

IMPORTANT

This unit must be matched with an indoor coil as
specified in Lennox Product Specification bulletin. Coils
previously charged with HCFC-22 must be flushed.

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 nearby these areas during installation or while
servicing this equipment.

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.

WARNING

The State of California has determined that this product
may contain or produce a chemical or chemicals, in very
low doses, which may cause serious illness or death. It
may also cause cancer, birth defects, or reproductive
harm.

General

The XP25 is a high-efficiency residential split-system heat
pump unit, which features a variable-capacity scroll
compressor and HFC-410A refrigerant. Units are available
in 2, 3, 4 and 5-ton sizes. The series is designed for use with
a check expansion valve (approved for use with HFC-410A)
in the indoor unit only.

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 HVAC components, ensure the
fasteners are appropriately tightened. Table 1 lists torque
values for fasteners.

Only use hex 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 a hex
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.

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 SET

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

Manifold gauge sets used with HFC-410A refrigerant
systems must be capable of handling 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 or up to 800 psig of
pressure with a 4000 psig burst rating.

Operating Service Valves

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

Each valve is equipped with a service port which has a
factory-installed valve stem. Figure 3 provides information
on how to access and operate both angle and ball-type
service valves.

Page 7

XP25

SERVICE VALVES

ANGLE AND BALL-TYPE

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.

SERVICE PORT CAP

SERVICE PORT CORE

(VALVE STEM SHOWN
CLOSED) INSERT HEX
WRENCH HERE

TO INDOOR

UNIT

(VALVE STEM SHOWN OPEN)
INSERT HEX WRENCH HERE

STEM CAP

TO OUTDOOR UNIT

ANGLE-TYPE SERVICE VALVE

(BACK-SEATED OPENED)

When service valve is OPEN, the service port is
open to line set, indoor and outdoor unit.

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°.

TO INDOOR UNIT

TO OPEN ROTATE STEM
COUNTERCLOCKWISE 90°.

TO CLOSE ROTATE STEM
CLOCKWISE 90°.

SERVICE PORT

SERVICE PORT

SERVICE PORT

CORE

CAP

TO OUTDOOR

UNIT

BALL (SHOWN
CLOSED)

VALV E
STEM

STEM CAP

ANGLE-TYPE SERVICE VALVE

(FRONT-SEATED CLOSED)

When service valve is CLOSED, the service port is open
to the line set and indoor 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:

11

7

12

6

1/6 TURN

1

2

4

5

1/12 TURN

• 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.

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:

10

9

8

• 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 addi
tional 1/12 turn clockwise.

10

9

12

11

8

1

5

7

6

3

2

3

4

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

Figure 3. Angle- and Ball-Type Service Valves

Page 8

XP25

II. INSTALLATION

Unit Placement

CAUTION

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

See Unit Dimensions on page 3 for sizing mounting slab,
platforms or supports. Refer to figure 4 for mandatory
installation clearance requirements.

POSITIONING CONSIDERATIONS

Consider the following when positioning the unit:

• Some localities are adopting sound ordinances based

on the unit 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 figure 6, detail A.

PLACING UNIT ON SLAB

When installing unit at grade level, the top of the slab should
be high enough above grade so that water from higher
ground will not collect around the unit. The slab should have
a slope tolerance as described in figure 6, detail B.

NOTE - If necessary for stability, anchor unit to slab as
described in figure 6, detail D.

Elevating the Unit

Units are outfitted with elongated support feet as illustrated
in figure 6, detail C.

If additional elevation is necessary, raise the unit by
extending the height of the unit support feet. Use a 2-inch
(50.8mm) Schedule 40 female threaded adapter to raise the
height of the unit.

The specified coupling fits snugly into the recessed portion
of the feet. Use additional 2-inch (50.8mm) Schedule 40
male threaded adaptors, which can be threaded into the
female threaded adaptors, to make additional adjustments
to the level of the unit.

NOTE - Keep the height of extenders short enough to
ensure a sturdy installation. If it is necessary to extend the
height further than what is stable, consider a different type
of field-fabricated framework that is sturdy enough for
greater heights.

CLEARANCE ON ALL SIDES — INCHES (MILLIMETERS)

6 (152)

12 (305)

36 (914)

ACCESS PANEL

CONTROL PANEL

ACCESS

LOCATION

30 (762)

LINE SET
CONNECTIONS

Note - Dimensions are not to scale.

NOTES:

• CLEARANCE TO ONE OF THE THREE

SIDES MUST BE 36 INCHES (914MM).

• CLEARANCE TO ONE OF THE

REMAINING TWO SIDES MAY BE 12
INCHES (305MM) AND THE FINAL
SIDE MAY BE 6 INCHES (152MM).

MINIMUM CLEARANCE BETWEEN

TWO UNITS

24 (610)

ACCESS PANEL

LINE SET

CONNECTIONS

MINIMUM CLEARANCE

ABOVE UNIT

48 (1219)

REAR VIEW OF UNIT

Figure 4. Installation Clearances

Page 9

XP25

STABILIZING UNIT ON UNEVEN SURFACES

IMPORTANT

unit above a load-bearing wall or area of the roof that can
adequately support the unit. Consult local codes for rooftop
applications.

Unit Stabilizer Bracket Use (field-provided):

Always use stabilizers when unit is raised above the
factory height. (Elevated units could become unstable in
gusty wind conditions.)

Stabilizers may be used on factory height units when
mounted on unstable an uneven surface.

1. Remove the louvered panel from each side to expose
the unit base.

2. Install the brackets as illustrated in figure 6, detail D
using conventional practices.

3. Replace the panels after installation is complete.

ROOF MOUNTING

NOTICE

Roof Damage!
This system contains both refrigerant and oil. Some

rubber roofing material may absorb oil and cause the
rubber to swell when it comes into contact with oil. The
rubber will then bubble and could cause leaks. Protect the
roof surface to avoid exposure to refrigerant and oil
during service and installation. Failure to follow this
notice could result in damage to roof surface.

If unit coil cannot be mounted away from prevailing
winter winds, a wind barrier should be constructed. Size
barrier at least the same height and width as outdoor
unit. Mount barrier 24 inches (610 mm) from the sides of
the unit in the direction of prevailing winds.

PREVAILING WINTER

WINDS

WIND BARRIER

INLET AIR

INLET AIR

INLET AIR

24”

(610)

Install the unit a minimum of six inches (152 mm) above the
roof surface to avoid ice build-up around the unit. Locate the

Figure 5. Wind Barrier

(Rooftop or Ground Application)

Page 10

XP25

DETAIL A DETAIL B

INSTALL UNIT AWAY FROM WINDOWS

TWO 90° ELBOWS INSTALLED IN LINE SET

REDUCES LINE SET VIBRATION.

Outside Unit Placement

INSTALL UNIT LEVEL OR, IF ON A SLOPE, MAINTAIN SLOPE
TOLERANCE OF 2 DEGREES (OR 2 INCHES PER 5 FEET [50 MM PER 1.5
M]) AWAY FROM BUILDING STRUCTURE.

GROUND LEVEL

Slab Mounting at Ground Level

BUILDING

STRUCTURE

MOUNTING
SLAB

DETAIL C

BASE

LEG DETAIL

2” (50.8MM) SCH 40

FEMALE THREADED

USE ADDITIONAL 2” SCH 40 MALE THREADED ADAPT
ERS WHICH CAN BE THREADED INTO THE FEMALE
THREADED ADAPTERS TO MAKE ADDITIONAL AD
JUSTMENTS TO THE LEVEL OF THE UNIT.

Elevated Slab Mounting using Feet

ADAPTER

2” (50.8MM) SCH 40

MALE THREADED

ADAPTER

Extenders

DETAIL D

Slab Side Mounting

#10 1/2” LONG SELF-DRILLING

SHEET METAL SCREWS

STABILIZING BRACKET (18 GAUGE

METAL — 2” WIDTH; HEIGHT AS

#10 1-1/4” LONG HEX HEAD

SCREW AND FLAT WASHER

CONCRETE SLAB — USE TWO PLASTIC
ANCHORS (HOLE DRILL 1/4”)

WOOD OR PLASTIC SLAB — NO PLASTIC ANCHOR
(HOLE DRILL 1/8”)

REQUIRED)

CORNER POST

MINIMUM ONE

Deck Top Mounting

STABILIZING BRACKET (18 GAUGE METAL
— 2” (50.8MM) WIDTH; HEIGHT AS
REQUIRED); BEND TO FORM RIGHT ANGLE

SAME FASTENERS AS
SLAB SIDE MOUNTING.

ONE BRACKET PER SIDE (MIN.); FOR EXTRA STABILITY, TWO
BRACKETS PER SIDE, 2” (50.8MM) FROM EACH CORNER.

PER SIDE

FOR EXTRA

STABILITY

Stabilizing Unit on Uneven Surfaces

IMPORTANT - To help stabilize an outdoor unit, some installations may require strap

ping the unit to the pad using brackets and anchors commonly available in the
marketplace.

COIL

BASE PAN

Figure 6. Placement and Slab Mounting

Page 11

XP25

Removing and Installing Panels

ACCESS PANEL REMOVAL

PANELS

ACCESS AND LOUVERED

REMOVE AND INSTALL THE ACCESS PANEL
AS ILLUSTRATED.

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.

IMPORTANT - Do not allow panels to hang on unit by top tab. Tab
is for alignment and not designed to support weight of panel.

PANEL SHOWN SLIGHTLY ROTATED TO ALLOW TOP TAB TO EXIT (OR ENTER) TOP SLOT FOR
REMOVING (OR INSTALLING) PANEL.

LOUVERED PANEL REMOVAL

Remove the louvered panels as follows:

1. REMOVE TWO SCREWS, ALLOWING THE PANEL TO SWING OPEN SLIGHTLY.

2. HOLD THE PANEL FIRMLY THROUGHOUT THIS PROCEDURE ROTATE BOTTOM

CORNER OF PANEL AWAY FROM HINGED CORNER POST UNTIL LOWER THREE TABS
CLEAR THE SLOTS AS ILLUSTRATED IN DETAIL B.

3. MOVE PANEL DOWN UNTIL LIP OF UPPER TAB CLEARS THE TOP SLOT IN CORNER

POST AS ILLUSTRATED IN DETAIL A.

LOUVERED PANEL INSTALLATION

Position the panel almost parallel with the unit as illustrated in detail D with the screw side
as close to the unit as possible. Then, in a continuous motion:

1. SLIGHTLY ROTATE AND GUIDE THE LIP OF TOP TAB INWARD AS ILLUSTRATED IN DETAIL
A AND C; THEN UPWARD INTO THE TOP SLOT OF THE HINGE CORNER POST.

2. ROTATE PANEL TO VERTICAL TO FULLY ENGAGE ALL TABS.

3. HOLDING THE PANEL'S HINGED SIDE FIRMLY IN PLACE, CLOSE THE RIGHT-HAND SIDE
OF THE PANEL, ALIGNING THE SCREW HOLES.

4. WHEN PANEL IS CORRECTLY POSITIONED AND ALIGNED, INSERT THE SCREWS AND
TIGHTEN.

Detail C

MAINTAIN MINIMUM PANEL ANGLE (AS CLOSE TO PARALLEL WITH THE UNIT AS
POSSIBLE) WHILE INSTALLING PANEL.

Detail D

Detail A

LIP

SCREW

HOLES

Detail B

REMOVE 4 SCREWS TO
REMOVE PANEL FOR
ACCESSING COMPRESSOR
AND CONTROLS.

ALIGN PANEL WITH SCREW
HOLES. INSTALL SCREWS
AND TIGHTEN.

ROTATE IN THIS DIRECTION; THEN

DOWN TO REMOVE PANEL

ANGLE MAY BE TOO EXTREME

PREFERRED ANGLE FOR INSTALLATION

Figure 7. Removing and Installing Panels

Page 12

HOLD DOOR FIRMLY ALONG

THE HINGED SIDE TO MAINTAIN

FULLY-ENGAGED TABS

XP25

New or Replacement Line Set

REFRIGERANT LINE SET

This section provides information on installation or
replacement of existing line set. If new or replacement line
set is not being installed, then proceed to Brazing
Connections on page 16.

IMPORTANT

Lennox highly recommends changing line set when
converting the existing system from HCFC-22 to
HFC-410A. If that is not possible and the line set is the
proper size as reference in table 2, use the procedure
outlined under Flushing the System on page 19.

IMPORTANT

If this unit is being matched with an approved line set or
indoor unit coil that 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
system performance and capacity.
Failure to properly flush the system per the XP25
Installation and Service Procedures will void the warranty.

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.
See figure 8 for recommended installation practices. Also,
consider the following when placing and installing a
high-efficiency outdoor unit.

Liquid lines that meter the refrigerant, such as RFC1 liquid
lines, must not be used in this application. Existing line set of
proper size (as listed in table 3) may be reused. If system
was previously charged with HCFC-22 refrigerant, the
existing line set must be flushed (see Flushing the System
on page 19).

IMPORTANT

Mineral oils are not compatible with HFC-410A. If oil must

be added, it must be a Polyol ester oil.

Recommended topping-off POE oils are Mobil EAL ARCTIC
22 CC or ICI EMKARATEt RL32CF.

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
unbrazing.

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.

WARNING

Fire, Explosion and Personal Safety Haz
ard. Failure to follow this warning could re
sult 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 fire
and/or an explosion, that could result in
property damage, personal injury or death.

WARNING

When using a high pressure gas such as
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).

IMPORTANT

Some scroll compressors have an internal vacuum
protector that will unload scrolls when suction pressure
goes below 20 psig. A hissing sound will be heard when
the compressor is running unloaded. Protector will reset
when low pressure in system is raised above 40 psig. DO
NOT REPLACE COMPRESSOR.

The XP25 is a variable-capacity cooling and heat pump
system utilizing variable-speed compressor technology.
With the variable-speed compressor and variable pumping
capacity, additional consideration must be given to
refrigerant piping sizing and application. The following
guidelines are to be used exclusively for the XP25 systems.

Page 13

XP25

COOLING SYSTEM (HFC-410A)

• Total equivalent length equals 180 feet (piping and all

fittings included).

NOTE - This is a general guide. Lengths may be more or
less, depending on remaining system design factors.

• Maximum linear (actual) length = 150 feet.

• Maximum linear liquid lift = 60 feet.

NOTE - Maximum lifts are dependent on total length,
number of elbows, and other factors that contribute to total
pressure drop.

• Maximum linear length of vapor riser = 60 feet.

• Size vertical vapor riser per table 3.

• Line set lengths up to 50 linear feet: Use rated line

sizes listed in table 2.

• Line set lengths between 51  150 linear feet:

Crankcase heater and nonbleed port TXV
factory-installed. No additional components required.

Table 2. Standard Refrigerant Line Set — Up to 50 Linear Feet

Inches (mm)

Valve Size Connections Recommended Line Sets

Model Number (-xx*)

XP25-024-230-XX
XP25-036-230-XX
XP25-048-230-XX

XP25-060-230-XX 3/8” (10 mm) 1-1/8” (29 mm) ** Field-fabricated

* Applicable to all minor revision numbers unless otherwise specified.
** Some applications may require a field-provided 1-1/8” to 7/8” adapter.

Liquid Line Suction Line

3/8” (10 mm) 7/8” (22 mm)

L15 Line Set
Model

L15-65-30 30 feet (9.1 m) 89J60

L15-65-40 40 feet (12.2 m) 89J61

L15-65-50 50 feet (15.2 m) 89J62

Vertical vapor riser must be sized per table 3 on systems
with line sets longer than 51 feet. Use tables 3 and 4 to
determine the correct liquid and vapor line sizes.

NOTE - See figure 65 on page 87 to calculate required
refrigerant charge.

• Line set lengths over 150 linear feet: Not

recommended.

• Additional oil is not required for systems with line lengths

up to 150 feet except for the XP25-048 and XP25-060.
These units require 2 ounces of oil for every 10 feet
beyond 100 feet.

NOTE - Recommended POE oils are Mobil EAL ARCTIC 22
CC or ICI EMKARATE

SUCTION TRAPS

In systems with the outdoor unit 5 to 60 feet above the
indoor unit, one trap must be installed at the bottom of the
suction riser.

®

RL32CF.

Line Set Length

Catalog
Number

Table 3. XP25 Piping Guidelines

Model

024 180 150 60 60 7/8” 5/8”

036 180 150 60 60 7/8” 3/4”

048 180 150 60 60 7/8” 7/8”

060 180 150 60 60 7/8” 7/8”

Maximum Total
Equivalent Length (ft)

Maximum Linear
(actual) Length (ft)

Maximum Vapor
Riser (ft)

Maximum
Linear Liquid
Lift (ft)

Preferred Vapor Line
Sizes for Horizontal
Runs

Required Vapor
Riser Size

Table 4. Liquid Line Diameter Selection Table

Total Linear Length (feet)

Unit

024

036

048

060

Note  Shaded rows indicate rated liquid line size.

1. Find your unit on the left side of the table.

2. Start with the rated liquid line size (shaded row) for the outdoor unit.

3. Select the actual total linear length of your system shown at the top of
the table.

Line Size

5/16”
3/8” 25 50 60 60 60 60

3/8” 25 50 60 56 51 45

1/2” 25 50 60 60 60 60

3/8” 25 50 50 41 31 22

1/2” 25 50 60 60 60 60

3/8” 25 50 36 22 8 NR

1/2”

25 50 75 100 125 150

25

25

50 55 48 40 33

50 60 60 60 59

4. The elevation listed in the table is the maximum allowed for the liquid
line listed.

5. Consider the larger liquid line size shown in the table if the elevation
does not meet your requirements.

Max. Elevation

(ft)

XP25

Page 14

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)

FLOOR JOIST OR

ROOF RAFTER

NON-CORROSIVE
METAL SLEEVE

TAPE OR
WIRE TIE

8 FEET (2.43 METERS)

WOOD BLOCK

BETWEEN

STUDS

SLEEVE

VAPOR LINE WRAPPED

WITH ARMAFLEX

OUTSIDE

WALL

PVC

PIPE

FIBERGLASS

INSULATION

CAULK

WIRE TIE

INSIDE WALL

STRAP

NON-CORROSIVE
METAL SLEEVE

WIRE TIE

WOOD BLOCK

WIRE TIE

STRAP

LIQUID
LINE

TAPE OR
WIRE TIE

FLOOR JOIST OR

ROOF RAFTER

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.

Figure 8. Line Set Installation

NOTE - SIMILAR INSTALLATION PRACTICES SHOULD BE USED IF

LINE SET IS TO BE INSTALLED ON EXTERIOR OF OUTSIDE WALL.

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.

Page 15

XP25

Brazing Connections

Use the procedures outlined in figures 9 and 10 for brazing
line set connections to service valves.

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).

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.

WARNING

Fire, Explosion and Personal Safety Haz
ard.

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 a fire
and/or an explosion, that could result in
property damage, personal injury or death.

Page 16

XP25

PIPING PANEL REMOVAL AND LINE SET
PREPARATION

1

Remove piping panel for easier access to service valves.
Cut ends of the refrigerant lines square (free from nicks or
dents) and debur the ends. The pipe must remain round. Do
not crimp end of the line.

CUT AND DEBUR

LINE SET SIZE MATCHES

SERVICE VALVE CONNECTION

SERVICE VALVE

COPPER TUBE

REDUCER

STUB

CONNECTION

LINE SET SIZE IS SMALLER

THAN CONNECTION

CAP AND CORE REMOVAL

Remove service cap and core from both the suction and

2

liquid line service ports.

SERVICE PORT CAP

SERVICE
PORT CORE

LIQUID LINE SERVICE VALVE

REFRIGERANT LINE

DO NOT CRIMP SERVICE

VALVE CONNECTOR WHEN

PIPE IS SMALLER THAN

CONNECTION

ATTACH THE MANIFOLD GAUGE SET FOR BRAZING
LIQUID AND SUCTION LINE SERVICE VALVES

3

A Connect gauge set low pressure side to liquid

line service valve (service port).

B Connect gauge set center port to bottle of

nitrogen with regulator.

C Remove the valve core from the suction line to

provide an exit point for the nitrogen flow.

SUCTION SERVICE PORT MUST BE OPEN AND

SERVICE PORT CORE REMOVED TO ALLOW

EXIT POINT FOR NITROGEN FLOW

SUCTION LINE

INDOOR

UNIT

C

SERVICE VALVE

SUCTION LINE SERVICE

LOW

ATTACH

GAUGES

SUCTION LINE

VALV E

B

HIGH

OUTDOOR

UNIT

SERVICE
PORT CORE

SERVICE
PORT CAP

LIQUID LINE

LIQUID LINE SERVICE

VALV E

A

Figure 9. Brazing Procedures

Page 17

NITROGEN

XP25

WRAP SERVICE VALVES

To help protect service valve seals during brazing, wrap water-saturated cloths around service valve bodies and copper tube
stubs. Use additional water-saturated cloths underneath the valve body to protect the base paint.

4

FLOW NITROGEN

Flow regulated nitrogen (at 1 to 2 psig) through the

5

refrigeration gauge set into the valve stem port connection
on the liquid service valve and out of the suction / vapor
valve stem port. See steps 3A, 3B and 3C on previous page
and below for manifold gauge setup.

BRAZE LINE SET

Cloths must remain water-saturated throughout the

6

brazing and cool-down process.

A Braze liquid line to liquid line service valve.

B Braze suction / vapor line to suction / vapor

service valve.

IMPORTANT !

Use silver alloy brazing rods with 5%
minimum silver alloy for copper-to-copper
brazing and 45% alloy for copper-to-brass
or copper-to-steel brazing.

6B

1. FIRE, PERSONAL INJURY, OR PROPERTY
DAMAGE will result if you do not wrap a water-

saturated cloth around both liquid and suction
line service valve bodies and copper tube stub
while brazing in the line set! The braze, when
complete, must be quenched with water to
absorb any residual heat.

2. Do not open service valves until refrigerant lines
and indoor coil have been leak-tested and
evacuated. Refer to procedures provided in this
supplement.

WHEN BRAZING LINE SET TO

SERVICE VALVES, POINT FLAME

AWAY FROM SERVICE VALVE.

WARNING

SUCTION / VAPOR LINE

WATER SATURATED CLOTHS

SUCTION / VAPOR SERVICE PORT

MUST BE OPEN AND SERVICE PORT

CORE REMOVED TO ALLOW EXIT

POINT FOR NITROGEN FLOW

IMPORTANT !

Allow braze joint to cool. Apply additional
water-saturated cloths to help cool brazed
joints. Do not remove water-saturated cloths
until piping has cooled. Temperatures above
250ºF will damage valve seals.

6A

LIQUID LINE

WATER SATURATED

PREPARATION FOR NEXT STEP

After all connections have been brazed, disconnect manifold gauge set from service ports. Apply additional water-saturated

7

cloths to both services valves to cool piping. Once piping is cool, remove all water-saturated cloths. Refer to the unit installation
instructions for the next step in preparing the unit.

CLOTHS

Figure 10. Brazing Procedures (Continued)

Page 18

XP25

Flushing the System

LINE SET AND INDOOR COIL (1 OF 2)

1B

TWO PIECE PATCH PLATE

TYPICAL EXISTING FIXED ORIFICE

1A

DISTRIBUTOR

ASSEMBLY

A ON FULLY CASED COILS, REMOVE THE COIL ACCESS AND PLUMBING

PANELS.

B REMOVE ANY SHIPPING CLAMPS HOLDING THE LIQUID LINE AND DIS

TRIBUTOR ASSEMBLY.

C USING TWO WRENCHES, DISCONNECT LIQUID LINE FROM LIQUID LINE

ORIFICE HOUSING. TAKE CARE NOT TO TWIST OR DAMAGE DISTRIBU
TOR TUBES DURING THIS PROCESS.

D REMOVE AND DISCARD FIXED ORIFICE, VALVE STEM ASSEMBLY (IF

PRESENT) AND TEFLON

E USE A FIELD-PROVIDED FITTING TO TEMPORARILY RECONNECT THE

LIQUID LINE TO THE INDOOR UNIT'S LIQUID LINE ORIFICE HOUSING.

CONNECT GAUGES AND EQUIPMENT FOR
FLUSHING PROCEDURE

2

VAPOR LINE

SERVICE VALVE

EXISTING

INDOOR

LIQUID LINE SERVICE

RECOVERY

CYLINDER

A INVERTED HCFC-22 CYLINDER WITH CLEAN REFRIGERANT TO THE

VAPOR SERVICE VALVE.

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 AN EMPTY RECOVERY TANK TO THE GAUGE SET.

D CONNECT RECOVERY TANK TO RECOVERY MACHINES PER MACHINE

INSTRUCTIONS.

REMOVAL PROCEDURE
(UNCASED COIL SHOWN)

DISTRIBUTOR TUBES

LIQUID LINE ORIFICE HOUSING

REMOVE AND DISCARD

WHITE TEFLON

(IF PRESENT)

®

WASHER AS ILLUSTRATED ABOVE.

INV ERT ED HCFC-22
CYLINDER CONTAINS
CLE AN HCFC-22 TO B E
USED FOR FLUSHING.

A

1

UNIT

VALV E

VAPOR

LIQUID

B

D

TEFLON® RING

FIXED ORIFICE

®

SEAL

NEW

OUTDOOR

UNIT

C

BRASS NUT

LIQUID LINE ASSEMBLY

(INCLUDES STRAINER)

GAUGE

MANIFOLD

LOW

OPENED

TANK
RETURN

INLET

DISCHARGE

RECOVERY MACHINE

CLOSED

HIGH

TYPICAL EXISTING EXPANSION VALVE
REMOVAL PROCEDURE (UNCASED COIL
SHOWN)

(UNCASED COIL ONLY)

DISTRIBUTOR

TUBES

OR

A ON FULLY CASED COILS, REMOVE THE COIL ACCESS AND PLUMBING

B REMOVE ANY SHIPPING CLAMPS HOLDING THE LIQUID LINE AND DIS

C DISCONNECT THE EQUALIZER LINE FROM THE CHECK EXPANSION

D REMOVE THE VAPOR LINE SENSING BULB.

E DISCONNECT THE LIQUID LINE FROM THE CHECK EXPANSION VALVE

F DISCONNECT THE CHECK EXPANSION VALVE FROM THE LIQUID LINE

G REMOVE AND DISCARD CHECK EXPANSION VALVE AND THE TWO TEF

H USE A FIELD-PROVIDED FITTING TO TEMPORARILY RECONNECT THE

DISTRIBUTOR

ASSEMBLY

MALE EQUALIZER

LINE FITTING

PANELS.

TRIBUTOR ASSEMBLY.

VALVE EQUALIZER LINE FITTING ON THE VAPOR LINE.

AT THE LIQUID LINE ASSEMBLY.

ORIFICE HOUSING. TAKE CARE NOT TO TWIST OR DAMAGE DISTRIBU
TOR TUBES DURING THIS PROCESS.

®

RINGS.

LON

LIQUID LINE TO THE INDOOR UNIT'S LIQUID LINE ORIFICE HOUSING.

LIQUID LINE

SENSING BULB

ORIFICE

HOUSING

EQUALIZER
LINE

STUB END

TEFLON
RING

VAPOR

CHECK

EXPANSION

VALV E

®

LIQUID LINE

ASSEMBLY WITH

BRASS NUT

LINE

TEFLON

RING

SENSING

FLUSHING LINE SET

3

CAUTION - This procedure should not be performed on sys

tems which contain contaminants (Example, compressor burn
out).

THE LINE SET AND INDOOR UNIT COIL MUST BE FLUSHED WITH AT
LEAST THE SAME AMOUNT OF CLEAN REFRIGERANT THAT PRE
VIOUSLY CHARGED THE SYSTEM. CHECK THE CHARGE IN THE

B

FLUSHING CYLINDER BEFORE PROCEEDING.

A 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 VACU
UM 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 RECOV

ERED, SWITCH THE RECOVERY MACHINE TO VAPOR RECOVERY
SO THAT ALL OF THE HCFC-22 VAPOR IS RECOVERED. ALLOW
THE RECOVERY MACHINE TO PULL SYSTEM DOWN TO 0.

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 OFF THE MACHINE.

®

LINE

LIQUID

LINE

Page 19

XP25

FLUSHING LINE SET AND INDOOR COIL (2 OF 2)

TYPICAL NEW CHECK EXPANSION VALVE INSTALLATION PROCEDURE

THIS OUTDOOR UNIT IS DESIGNED FOR USE IN SYSTEMS THAT USE A CHECK EXPANSION VALVE METERING DEVICE. SEE THE LENNOX XP25
PRODUCT SPECIFICATION FOR APPROVED EXPANSION VALVE KIT MATCH-UPS AND APPLICATION INFORMATION.

4

THE EXPANSION VALVE UNIT CAN BE INSTALLED INTERNAL OR
EXTERNAL TO THE INDOOR COIL. IN APPLICATIONS WHERE AN

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. SEE SENSING BULB
INSTALLATION FOR BULB POSITIONING.

(Uncased Coil Shown)

LIQUID LINE

ORIFICE

HOUSING

STUB

END

TEFLON
RING

EQUALIZER
LINE

EXPANSION

VALV E

®

LIQUID LINE

ASSEMBLY WITH

BRASS NUT

VAPOR

LINE

UNCASED COIL IS BEING INSTALLED IN A FIELD-PROVIDED
PLENUM, INSTALL THE CHECK EXPANSION VALVE IN A MANNER
WHICH PROVIDES ACCESS FOR FIELD SERVICING OF THE
EXPANSION VALVE. REFER TO BELOW ILLUSTRATION FOR
REFERENCE DURING INSTALLATION OF EXPANSION VALVE
UNIT.

®

TEFLON

RING

A REMOVE THE FIELD-PROVIDED FITTING THAT TEMPORARILY RECON

NECTED THE LIQUID LINE TO THE INDOOR UNIT'S DISTRIBUTOR AS

SENSING

LINE

LIQUID LINE

SEMBLY.

B INSTALL ONE OF THE PROVIDED TEFLON

STUBBED END OF THE 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 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 IL
LUSTRATED IN THE FIGURE ABOVE, OR 20 FT-LB.

D PLACE THE REMAINING TEFLON

OF THE EXPANSION VALVE. LIGHTLY LUBRICATE CONNECTOR
THREADS AND EXPOSE SURFACE OF THE TEFLON
FRIGERANT OIL.

E ATTACH THE LIQUID LINE ASSEMBLY TO THE EXPANSION VALVE. FIN

GER 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.

9 O'CLOCK TO

3 O'CLOCK

BULB

12

®

BULB

9

WASHER AROUND THE OTHER END

12

11

10

8

7

6

®

RINGS AROUND THE

®

ON LINES SMALLER THAN
7/8”, MOUNT SENSING
BULB BETWEEN THE 9
AND 3 O'CLOCK
POSITIONS.

SENSING BULB INSTALLATION

VAPOR LINE

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 VA
POR LINE AND CHECK EXPANSION BULB BEFORE INSULATING
THE SENSING BULB ONCE INSTALLED.

B CONNECT THE EQUALIZER LINE

FROM THE EXPANSION VALVE TO
THE EQUALIZER VAPOR PORT ON
THE VAPOR LINE. FINGER
TIGHTEN THE FLARE NUT PLUS
1/8 TURN (7 FT-LBS) AS ILLUS
TRATED BELOW.

9

10

11

12

1

8

7

5

6

1/8 TURN

2

3

4

VAPOR LINE

BULB

FLARE SEAL CAP

ON 7/8” AND LARGER LINES,
MOUNT SENSING BULB AT
EITHER THE 4 OR 8 O'CLOCK
POSITION. NEVER MOUNT

12

BULB

NOTE - NEVER MOUNT THE SENSING BULB ON

BOTTOM OF LINE.

THE SENSING BULB ON
BOTTOM OF LINE.

FLARE NUT

1/2 TURN

1

2

3

4

5

®

RING WITH RE

EQUALIZER LINE INSTALLATION

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.

Page 20

OR

COPPER FLARE
SEAL BONNET

MALE BRASS EQUALIZER
LINE FITTING

VAPOR LINE

XP25

INSTALLING ISOLATION GROMMETS

Locate the isolation grommets (provided). Slide grommets
onto vapor and liquid lines. Insert grommets into piping
panel to isolate refrigerant lines from sheet metal edges.

PIPING PANEL

SUCTION LINE

Leak Testing the System

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).

LIQUID LINE

TWO ISOLATION GROMMETS
ARE PROVIDED FOR THE
LIQUID AND SUCTION LINE PIPE
PANEL PASS THROUGH.

REAR VIEW OF UNIT EXTERIOR

Figure 11. Isolation Grommets

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

Leak detector must be capable of sensing HFC
refrigerant.

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.

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.

Page 21

XP25

LEAK TEST

LINE SET AND INDOOR COIL

CONNECT GAUGE SET

1

A CONNECT AN HFC-410A MANIFOLD GAUGE SET

HIGH 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 IS 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.

LOW

HIGH

MANIFOLD GAUGE SET

OUTDOOR UNIT

A

NITROGEN

HFC-410A

B

TO VAPOR

SERVICE VALVE

TEST FOR LEAKS

AFTER THE LINE SET HAS BEEN CONNECTED TO THE INDOOR AND OUTDOOR UNITS, CHECK THE LINE SET CON

2

NECTIONS AND 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.

Figure 12. System Leak Test

Page 22

XP25

Evacuating the System

LINE SET AND INDOOR COIL

CONNECT GAUGE SET

1

NOTE - REMOVE CORES FROM SERVICE VALVES (IF

NOT ALREADY DONE).

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 TO AN

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 IS USED LATER
FOR BOTH THE HFC-410A AND
NITROGEN CONTAINERS.

OUTDOOR

UNIT

A

A34000 1/4 SAE TEE WITH
SWIVEL COUPLER

500

C

MICRON

GAUGE

LOW

TO VAPOR

SERVICE VALVE

MANIFOLD

GAUGE SET

HIGH

HFC-410A

B

TO LIQUID LINE
SERVICE VALVE

VACUUM PUMP

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 REFERS TO THE TOTAL ACTUAL PRESSURE (ABOVE ABSOLUTE ZERO) WITHIN A GIVEN VOLUME OR

SYSTEM. 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 IN

DOOR 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:

D

RECOMMEND

MINIMUM 3/8” HOSE

1/6 TURN

1. Close manifold gauge valves.

2. Shut off HFC-410A cylinder.

3. Reinstall service valve cores by removing manifold hose from service valve. Quickly install cores with
core tool while maintaining a positive system pressure.

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

Figure 13. System Evacuation

Page 23

9

10

8

11

12

1

2

3

4

7

5

6

XP25

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 combined 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. See unit nameplate

for minimum circuit ampacity and maximum over-current
protection size.

24VAC TRANSFORMER

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

LOAD SHEDDING
Utility Load Shedding Mode ACTIVATED – The normally

closed set of contacts in the utility load shedding control
receiver OPEN. This removes 24VAC from the coil of the
field-provided relay (catalog # 69J79). The relay contacts
close (terminal 7 to terminal 2), completing the circuit
between terminals R and L on the outdoor control. The
24VAC input to terminal L activates the load shedding mode
in the outdoor control, cycling the outdoor unit OFF. The
7-Segment display on the outdoor control displays a load
shedding alert code (E600) and an alert appears on the
display of the iComfort Wi-Fi
receives email notifications when the alert occurs, if the
option to receive notifications is selected.

Utility Load Shedding Mode DEACTIVATED
(Normal Equipment Operation) – When load shedding is

not required, the contacts in the utility load control receiver
are closed. This provides 24VAC to the coil of the
field-provided relay (catalog # 69J79).The relay contacts
OPEN (terminal 7 to terminal 2) removing 24VAC from the L
terminal on the outdoor control. This deactivates the load
shedding mode in the outdoor control. The outdoor unit
returns to normal operation and alert code clears once load
shedding mode is deactivated.

For more information, see the Load Shedding Feature
Wiring Diagram on page 48.

®

thermostat. The customer

SIZE CIRCUIT AND INSTALL DISCONNECT
SWITCH

1

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.

SERVICE

DISCONNECT

SWITCH

NOTE - UNITS ARE APPROVED FOR USE ONLY WITH COPPER
CONDUCTORS. GROUND UNIT AT DISCONNECT SWITCH OR TO AN
EARTH GROUND.

Figure 14. Electrical

INSTALL THERMOSTAT

INSTALL ROOM THERMOSTAT (ORDERED SEPARATELY) ON AN
INSIDE WALL APPROXIMATELY IN THE CENTER OF THE

2

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 CON
TROL BOX.

Page 24

XP25

ROUTE CONTROL WIRES

Maximum length of wiring (18 gauge) for all connections on

3

the RSBus is 1500 feet (457 meters). Wires should be col
or-coded, with a temperature rating of 95
mum, and solid-core (Class II Rated Wiring). All low volt
age wiring must enter unit through the provided field­installed busing installed in the electrical inlet.

The iComfort Wi-Fi
wires between the thermostat and the furnace / air handler
iComfort
and the furnace/air handler iComfort® control. When a
thermostat cable with more than four wires is used, the ex
tra wires must be properly connected to avoid electrical
noise (see below).

Use a wire nut to bundle the four unused wires at each end
of the cable. Each bundle should also include an additional
wire that should be connected on each end to the C termi
nal as shown in the figure below.

Provided Rast

6-PIN Connector

®

control and four wires between the outdoor unit

®

thermostat requires four thermostat

Outdoor Control

º

F (35ºC) mini

ELECTRICAL (CONTROL WIRING)

AND LINE SET INLETS USE
BUSHING AND GROMMETS

PROVIDED IN BAG

BUSHING

GROMMETS

Indoor Control

TYPICAL CONTROL BOX

CONTROL WIRING
ROUTE (LOW VOLTAGE)

OUTDOOR CONTROL

iComfort Wi-Fi

thermostat

®

Single Wire To

C Terminal

Unused Wires

ROUTE HIGH VOLTAGE AND GROUND WIRES

4

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 side panel of
the control box. Connect conduit to the control box using a proper conduit fitting.

ELECTRICAL INLET

(HIGH VOLTAGE)

WATERTIGHT

FLEXIBLE CONDUIT

Single Wire To C Terminal

Unused Wires

GROUND LUGS

CONTACTOR

TO SERVICE

DISCONNECT BOX

Figure 15. Electrical (Continued)

XP25

Page 25

ELECTRICAL (Continued) -- Outdoor Unit Control

CAUTION

Electrostatic discharge can affect electronic components. Take precautions

ELECTROSTATIC DISCHARGE

(ESD)

Precautions and Procedures

during unit installation and service to protect the unit's electronic controls.
Precautions will help to avoid control exposure to electrostatic discharge by
putting the unit, the control and the technician at the same electrostatic potential.
Neutralize electrostatic charge by touching hand and all tools on an unpainted
unit surface before performing any service procedure

NOTE - The green LED located on the outdoor control
flashes when communication occurs between the outdoor
control and either the thermostat or the inverter.

Figure 16. Outdoor Unit Control

Page 26

7-SEGMENT

DISPLAY

PUSH

BUTTON

PUMP DOWN - WHEN UNIT IS IN PUMP DOWN MODE,  IS

SHOWN ON THE 7-SEGMENT DISPLAY.

TO ACTIVATE MODE, REFER TO PUMP DOWN CYCLE

SEQUENCE ON PAGE 39.

XP25

TABLE 5

Outdoor Control Terminal Designations and Input /Outputs (see figure 16 for terminal locations)
Designator Description Input Output Common

O OUT Reversing valve switched output N/A

O Reversing valve return N/A N/A 24VAC common

LO PS Low Pressure switch N/A 5ma @18VAC N/A

LO PS

Hi PS High Pressure switch N/A 24VAC nominal N/A

Hi PS

TP

TP

Cntctr

Cntctr Contactor common N/A 24VAC common

Fan PWM PWM fan output N/A

COM PWM Fan common connection N/A N/A Fan PWM common

Fan Park

P2 Terminals

O O (reversing valve) emergency input

Y1 Y1 emergency input

C 24VAC nominal power return. N/A N/A 24VAC common

i Low data line. Data Data N/A

i+ High data line. Data Data N/A

R 24VAC nominal power input.

DF Factory test N/A N/A N/A

TOUT

TST

Low Pressure switch sensing con
nection

High pressure switch sensing con
nection

Top cap thermostat switch (in series
with the HI PS)

Top Cap thermostat switch sensing
connection

Control (Inverter power) contactor
switched output (in series with the HI
PS and TC)

PWM Fan Parking spot for unused
terminal, not connected.

26Vdc transistor output to Lennox
factory OEM tester

Factory test pin.
In each terminal box:

P2  Terminal 1  TEST
P2  Terminal 2  TOUT
P2  Terminal 3  DF
P2  Terminal 4  R

5ma @18VAC N/A N/A

24VAC nominal N/A N/A

N/A 24VAC nominal N/A

24VAC nominal N/A N/A

N/A

N/A N/A N/A

24VAC nominal from
thermostat and loaded to
draw 17ma at 30VAC

24VAC nominal from
thermostat and loaded to
draw 17ma at 30VAC

24VAC nominal board
main power input.

N/A N/A N/A

24VAC nominal 17ma @
30VAC

Switched 24VAC
nominal

Switched 24VAC
Nominal

1097% duty cycle,
1923 VDC peak

N/A N/A

N/A N/A

N/A N/A

N/A N/A

N/A

N/A

N/A

Page 27

XP25

Table 5 continued.

Outdoor Control Terminal Designations and Input /Outputs

WARNING - Electric Shock Hazard. Can cause injury or death. Unit must be grounded in accordance with national and local codes. The 4 pins in

P6 have the potential of transferring up to 250 volts to the unit cabinet ground.

Designator Description Input Output Common

P6 - Pin 1 Tx

Inverter

P6 - Pin 2

P6 - Pin 3 Rx

P6 - Pin 4 Inv 5V Inverter 5VDC volts. Inverter 5VDC volts

LIQ Liquid line temperature sensor supply. N/A N/A N/A

LIQ Liquid line temperature sensor return. N/A N/A N/A

AMB Outdoor ambient temperature sensor supply. N/A N/A N/A

AMB Outdoor ambient temperature sensor return. N/A N/A N/A

COIL Outdoor coil temperature sensor supply. N/A N/A N/A

COIL Outdoor coil temperature sensor return. N/A N/A N/A

Pump Down

L Load shedding input.

C

Com
mon

Transmit data to inverter, connects to Rx of
inverter.

Inverter common

NOTE - This is a signal reference point and not

an earth ground

Receive data from the inverter. Connects to
Tx of inverter.

To initiate pump down function, place jumper
in the ON position. (See Pump Down Mode
Operation on Page 39.)

1. Place the jumper in the ON position to

activate pump down mode.

2. Place the jumper in the OFF position to

deactivate pump down mode.

NOTE - If the pump down jumper is in the ON
position during power-up, it is ignored.

NOTE - The outdoor control stays in pump
down mode for five minutes
outdoor control initiates a compressor
shutdown sequence.

Load shedding input reference. Refer to wir
ing of load shedding terminals in the Unit Wir
ing Diagram section of this manual on page

46.

.

, after which the

Outdoor control
communication transmit
pin.

Inverter common.

Outdoor control
communication receive
pin.

PUMP

DOWN

24VAC input to L ener
gizes load shedding fea
ture.

N/A N/A

• Pin 1 to pin 2 should read 4.5 to 5.5
VDC when not communicating.

• Pin 3 to pin 2 should read 4.5 to 5.5
VDC when not communicating.

• Pin 4 to pin 2 should read 4.5 to 5.5
VDC.

NOTE - Communication signals switch
off and on rapidly. This may cause volt
meter readings to fluctuate. This is nor
mal. Communication signals will switch
between this 5V and common (Pin 2).

ON

OFF

PUMP
DOWN

N/A N/A

ON

OFF

24VAC com
mon

Page 28

XP25

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 21.

2. Evacuate the system using procedure outlined on
page 23.

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 23.

5. Weigh in refrigerant using procedure outlined in
figure 65 on page 87.

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

1. Rotate fan to check for binding.

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

3. After evacuation is complete, open both the liquid and
vapor line service valves to release the refrigerant
charge contained in outdoor unit 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 unit and close the outdoor unit disconnect
switch to start the unit.

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.

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

8. Check system for sufficient refrigerant by using the
procedures listed under System Refrigerant.

Page 29

XP25

III. SYSTEM OPERATION AND SERVICE

7-Segment Alert and System Status Codes

Alert codes are displayed using the 7-segment display
located on the outdoor control.

NOTE - System fault and lockout codes take precedence
over system status codes (cooling, heating operating
percentages or defrost/dehumidification).

The 7-segment display shows an abnormal condition (error
code) when detected in the system. A list of the codes are
shown in table 6.

RESETTING ALERT CODES

Alert codes can be reset manually or automatically:

1. Manual Reset

Use one fo the following methods to manually reset the
system:

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).
Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

Alert

Codes

N/A N/A ON OFF N/A XC/XP 25-024 and -036 only: Indicates inverter is operating normally.

N/A N/A ON ON N/A XC/XP 25-048 and -060 only: Indicates inverter is operating normally.

N/A N/A OFF OFF N/A Indicates inverter is NOT energized.

E 105 N/A N/A N/A Moderate

E 120 N/A N/A N/A Moderate

E 124 N/A N/A N/A Critical

E 125 N/A N/A N/A Critical

E 131 N/A N/A N/A Critical

E 132 N/A N/A N/A Critical Internal software error. Replace outdoor control.

E 180 N/A N/A N/A Critical

Table 6. Outdoor Control 7-Segment Display Alert Codes and Inverter LED Flash Codes

®

thermostat.

Inverter LED Flash

Inverter
Code

Code (number of
flashes)

Red LED Green LED

Priority Alarm Description Possible Causes and Clearing Alarm

The outdoor control has
lost communication with
either the thermostat or in
door unit.

There is a delay in the out
door unit responding to the
system.

The iComfort WiFi® ther
mostat has lost communic
ation with the outdoor unit
for more than 3 minutes.

There is a hardware prob
lem with the outdoor con
trol.

The outdoor unit control
parameters are corrupted.

The outdoor unit ambient
temperature sensor has
malfunctioned. As a result
the outdoor unit control will
not perform low ambient
cooling.

 Disconnecting R wire from the outdoor control R

terminal.

 Turning the indoor unit off and back on again

After power up, all currently displayed codes are
cleared.

2. Automatic Reset

After an alert is detected, the outdoor control continues
to monitor the system and compressor operations.
When/if conditions return to normal, the alert code turns
off automatically.

NOTE - Error codes can be recalled by following information
in tables on page 34.

Equipment is unable to communicate. Indicates nu
merous message errors. In most cases errors are re
lated to electrical noise. Make sure high voltage power
is separated from RSBus. Check for miswired and/or
loose connections between the stat, indoor unit and
outdoor unit. Check for a high voltage source of noise
close to the system. Fault clears after communication
is restored.

Typically, this alarm/code does not cause any issues
and clears on its own. The alarm/code is usually
caused by a delay in the outdoor unit responding to the
thermostat. Check all wiring connections. Cleared
after unresponsive device responds to any inquiry.

Equipment lost communication with the thermostat.
Check the wiring connections and resistance, then
cycle the system power. This alarm stops all associ
ated HVAC operations and waits for a signal from the
non-communicating unit. The alarm / fault clears after
communication is reestablished.

There is a control hardware problem. Replace the out
door control if the problem prevents operation and is
persistent. The alarm / fault is cleared 300 seconds after
the fault recovers.

Reconfigure the system. Replace the control if heating or
cooling is not available.

Valid temperature reading is lost during normal opera
tion and after outdoor control recognized sensors.
Compare outdoor sensor resistance to temperature/
resistance charts in unit installation instructions. Re
place sensor pack if necessary. At the beginning of
(any) configuration, furnace or airhandler control de
tects the presence of the sensor(s). If detected (reading
in range), appropriate feature is shown in the iComfort

®

WiFi

thermostat About screen. The alarm / fault clears

upon configuration, or when normal values are sensed.

XP25

Page 30

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).

Table 6. Outdoor Control 7-Segment Display Alert Codes and Inverter LED Flash Codes

Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

Inverter LED Flash

Alert

Codes

Inverter
Code

Code (number of
flashes)

Red LED Green LED

E 345 N/A N/A N/A Critical

E 409 N/A N/A N/A Moderate

E 410 N/A N/A N/A Moderate

E 411 N/A N/A N/A Critical

E 412 N/A N/A N/A Moderate

E 413 N/A N/A N/A Critical

®

thermostat.

Priority Alarm Description Possible Causes and Clearing Alarm

Issue: Broken R50 will make the control board think

reversing valve output is always off regardless of state
of relay. (Supplier issue - We have found our functional

Heat Pump or Air Condition
er Alert Code - The "O" re
lay on the outdoor board
has failed. Either the pilot
relay contacts did not close,
the relay coil did not ener
gize or the circuit that con
firms this operational se
quence is not sensing prop
erly.

test fixture can bend over MOV2 and crush it into
R50.There are cut-outs in the plate of the fixture to let
the two relays pass through as the plate with pogo pins
is moved to the board to make contact with the termin
als. There is a pocket milled out in the plate to let
MOV2 pass, but if MOV2 is not straight up, it could
catch the plate outside the pocket and be bent down to
the board. Lennox is enlarging the cut-outs in the plate
so MOV2 will clear the fixture. Corrective action com
pleted on August 29,2013.

Corrective Actions: Short term fix: Converted the sys
tem back to a 24 volt system to get unit operating. Long
term: Replace outdoor control.

Secondary voltage is below 18VAC. After 10 minutes,

Outdoor control secondary
voltage is 18VAC or less.

operation is discontinued. Check the indoor line voltage
and transformer output voltage. The alarm clears after
the voltage is higher than 20VAC for 2 seconds or after
a power reset.

Unit pressure is below the lower limit. The system is
shutdown. The low pressure switch opens at 25PSIG

and closes at 40PSIG. Confirm that the system is prop
The outdoor unit low pres
sure switch has closed.

erly charged with refrigerant. Check TXV, indoor unit

blower motor, dirty filters or clogged refrigerant filter.

Confirm that the evaporator coil is clean. The alarm

clears after the pressure switch opens or after a power

reset.

Low pressure switch error count reached 5 strikes. The

The low pressure switch has
opened 5 times within one
hour. As a result, the out
door unit is locked out

.

low pressure switch opens at 40PSIG and resets at

90PSIG. Confirm that the system is properly charged

with refrigerant. Check for clogged TXV, blockage to

indoor unit blower motor, dirty filters or clogged refriger

ant filter. Confirm that the evaporator coil is clean. The

alarm clears after a power reset.

Unit pressure is above the upper limit. System is shut

down. The high pressure switch opens at 590PSIG

and closes at 418PSIG. Confirm that the system is

properly charged with refrigerant. Check for clogged
The outdoor unit high pres

sure switch has opened.

TXV, blockage to indoor unit blower motor, clogged

refrigerant filter. Confirm that the outdoor unit is clean.

The alarm clears after the pressure switch closes or a

power reset.

For heating, indoor CFM may be set too low. For zon

ing system, zone CFM may be set too low.

Open high pressure switch error count reached 5

strikes. System is shut down. The high pressure switch

for HFC410A opens at 590PSIG and closes at

The high pressure switch
has opened 5 times within
one hour. As a result, the
outdoor unit is locked out

418PSIG. Confirm that the system is properly charged

with refrigerant. Check condenser fan motor, for

clogged TXV, for blockage to indoor unit blower motor,

for stuck reversing valve or clogged refrigerant filter.

.

Confirm that the outdoor unit is clean. The alarm clears

after a power reset.

For heating, indoor CFM may be set too low. For zon

ing system, zone CFM may be set too low.

Page 31

XP25

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).

Table 6. Outdoor Control 7-Segment Display Alert Codes and Inverter LED Flash Codes

Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

Inverter LED Flash

Alert

Codes

Inverter
Code

Code (number of
flashes)

Red LED Green LED

E 416 N/A N/A N/A

E 422 N/A N/A N/A Moderate

E 423 40 4 flashes OFF

E 424 N/A N/A N/A Moderate

E 425 N/A N/A N/A Minor

E 426 N/A N/A N/A Critical Excessive inverter alarms

E 427 21 2 flashes 1 flash

E 428 22 2 flashes 2 flashes

®

thermostat.

Priority Alarm Description Possible Causes and Clearing Alarm

Coil sensor being detected open or shorted, or temper

ature is out of coil sensor range. Outdoor unit control

Moderate
/ Critical

The outdoor coil sensor has
malfunctioned. As a result
the outdoor unit control will
not perform defrost.

will not perform demand or time/temperature defrost

operation. System is still able heat and cool. Check the

resistance of the coil sensor and compare to temperat

ure resistance chart. Replace coil sensor if needed.

The alarm clears when outdoor unit control detects

proper coil sensor readings or after a power reset.

Issue: One of the wires from the top cap switch had

Compressor top cap switch
exceeding thermal limit.

pulled off one of the TP terminals on the outdoor con

trol board.

Corrective Action: Reconnected wire onto top cap

terminal.

Moderate
/ Critical

The inverter has detected a
circuit problem.

Control locks out after 10 strikes within an hour. To

clear, disconnect power to outdoor unit and restart.

In normal operation, after outdoor control recognizes

sensors, the alarm is sent if valid temperature reading

is lost. Compare liquid line sensor resistance to tem

perature/resistance charts in unit installation instruc

The liquid line temperature
sensor has malfunctioned.

tions. Replace sensor pack if necessary. At the begin

ning of (any) configuration, furnace or airhandler con

trol detects the presence of the sensor(s). If detected

(reading in range), appropriate feature is shown in the

iComfort WiFi

®

thermostat About screen. The alarm /
fault clears upon configuration, or when normal values
are sensed.

Outdoor control has in
creased minimum com
pressor speed to allow for
proper oil return due to low
ambient temperature. NOTE -
Minimum speed adjustments
begin at 45°F and increase to

Outdoor ambient temperature is below system limit.
Control attempts to run at lowest allowed compressor
speed to allow for proper oil return. Automatically
clears when outdoor ambient temperature rises above
limit for more than 5 minutes.

100% minimum at 17°F.

After ten faults within one hour, control is locked out,
indicating poor system operation. Review history of
alarms to resolve system setup. Check condenser fan
motor, TXV, indoor unit blower motor, over-charge, un
dercharge, or clogged refrigerant filter.

To clear error, disconnect power to outdoor unit and
restart. Inverter alarms 12 to 14 and 53 do not count
toward this lock out condition.

The inverter has detected a DC peak fault condition. If condition (55A or higher) is

Moderate
/ Critical

detected, outdoor unit compressor and fan stop. Anti-short cycle is initiated. If peak
current (55A or higher) occurs 10 times within an hour, system is locked out. Indicates
high pressure, condenser fan failure, locked compressor rotor or overcharge. To clear,
disconnect power to outdoor unit and restart.

If condition is detected, is detected, outdoor unit com
pressor and fan stop. Antishort cycle is initiated. If

Moderate
/ Critical

The inverter has detected a
high main input current con

.

dition

condition occurs 5 times within an hour, system is
locked out.
Indicates high pressure, condenser fan failure or over
charge.

To clear, disconnect power to outdoor unit and restart.

Page 32

XP25

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).

Table 6. Outdoor Control 7-Segment Display Alert Codes and Inverter LED Flash Codes

Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

Inverter LED Flash

Alert

Codes

E 429 23 2 flashes 3 flashes

E 430 26 2 flashes 6 flashes

E 431 27 2 flashes 7 flashes

E 432 28 2 flashes 8 flashes

E 433 29 2 flashes 9 flashes

Inverter
Code

Code (number of
flashes)

Red LED Green LED

®

thermostat.

Priority Alarm Description Possible Causes and Clearing Alarm

Issues:

(1) If DC link power in inverter does not rise above 180
VDC for 2- and 3-ton models, 250 VDC for 4- and 5-ton
models, within 30 seconds, the outdoor control will dis
play a moderate code.

(2) Capacitors on inverter do not properly charge.

Corrective Actions:

(1) check for proper main power to outdoor unit and for
any loose electrical connections.

(2) Outdoor control boards with part # 103686-03 have
software update to delay the de-energizing of the re
versing valve by four seconds when coming out of de
frost.

If condition is detected, outdoor unit compressor and
fan stop. Antishort cycle is initiated. If condition occurs
10 times within an hour, system is locked out.

Indicates poor connection at compressor harness, im
proper winding resistance, locked compressor rotor, or
flooded compressor.

To clear, disconnect power to outdoor unit and restart.

Issues:

(1) Indicates power interruption, brownout, poor elec
trical connection or loose inverter input wire.

(2) System testing was set up and code was gener
ated when the reversing valve is de-energized coming
out of defrost (code appears with or without 30 com
pressor delay).

Corrective Actions:

(1) Check for proper main power to outdoor unit and
for any loose electrical connections.

(2) Outdoor control boards with part # 103686-03 have
software update to delay the de-energizing of the re
versing valve by four seconds when coming out of de
frost.

Error occurs when the DC link capacitor voltage is greater
than 480VDC. If condition is detected, outdoor unit com
pressor and fan stop. Antishort cycle is initiated. If condi
tion occurs 10 times within an hour, system is locked out.
System stops. To clear, disconnect power to outdoor unit
and restart.

Error occurs when compressor peak phase current is
greater than 28A. Inverter issues code 14 first and slows
down to try to reduce the current. If the current remains
high, outdoor unit compressor and fan stop. Antishort
cycle is initiated. If condition occurs five times within an
hour, system is locked out. To clear disconnect power to
outdoor unit and restart.

Moderate
/ Critical

Moderate
/ Critical

Moderate
/ Critical

Moderate

/ Critical

Moderate

/ Critical

On a call for compressor op
eration, if DC link power in
inverter does not rise above
180 VDC for 2 and 3 ton
models, 250 VDC for 4 and
5 ton models, within 30
seconds, the control will dis
play a moderate code. If
condition is detected, out
door unit will stop (Com
pressor and fan). Anti-short
cycles is initiated. If condi
tion occurs 10 times within a
60 minute rolling time peri
od, system will lock out and
display a critical code.

Compressor start failure.

Error occurs when PFC de
tects an over-current condi
tion of 100A, the control will
display a moderate code. If
condition is detected, out
door unit will stop (Com
pressor and fan). Anti-short
cycle is initiated. Inverter is
unavailable to communicate
with the outdoor control for
3 minutes. If condition oc
curs 10 times within a 60
minute rolling time period,
system will lock out and dis
play a critical code.

The inverter has detected a
DC link high voltage condi
tion.

The inverter has detected a
compressor over-current
condition

.

Page 33

XP25

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).

Table 6. Outdoor Control 7-Segment Display Alert Codes and Inverter LED Flash Codes

Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

Inverter LED Flash

Alert

Codes

Inverter
Code

Code (number of
flashes)

Red LED Green LED

E 434 53 5 flashes 3 flashes

E 435 60 6 flashes OFF

E 436 62 6 flashes 2 flashes

E 437 65 6 flashes 5 flashes

E 438 73 7 flashes 3 flashes

E 439 12 1 flash 2 flashes Moderate

®

thermostat.

Priority Alarm Description Possible Causes and Clearing Alarm

Outdoor control has lost
communications with the

Issues:

(1) Loose electrical connections.

(2) Interruption of main power to inverter.

Corrective Actions:

(1) Check all electrical connections.

(2) Check for proper main power to inverter.

Moderate /
Critical

inverter for greater than 3
minutes. Outdoor control
will stop all compressor de
mands, recycle power to
the inverter by de-energiz
ing the contactor for 2
minutes. If this occurs 3
time in one thermostat call,
the outdoor unit will locked
out and display a critical
code.

When this error occurs, the outdoor control cycles

Moderate /
Critical

Inverter internal error.

power to the inverter by opening the contactor for two
minutes. Check that the EEPROM is properly seated.
After power is cycled to the inverter 3 times, the out
door unit is locked out

.

Inverter heat sink temperat
ure exceeded limit. Occurs

Moderate /
Critical

when the heat sink temper
ature exceeds the inverter
limit. Inverter issues code
13 first, then slows down to
allow the heat sink to cool. If
temperature remains high,
outdoor unit stops (com
pressor and fan). Anti-short
cycle is initiated. If condition
occurs 5 times within an
hour, system is locked out.

Issue: Feedback from supplier tear down of inverter in
dicates that the screws that hold the inverter to the invert
er board were loose causing poor contact between these
two components.

Corrective Action: Tighten screws that hold the heat
sink to the inverter control board.

NOTE: Wait five minutes to all capacitor to discharge be
fore checking screws.

To clear, disconnect power
to outdoor unit and restart.

Occurs when the temperature sensor detects a temperat

Moderate /
Critical

Heat sink temperature
sensor fault has occurred
(temperature less than 4ºF
or greater than 264ºF after
10 minutes of operation)

ure less than 0.4ºF or greater than 264ºF after 10 minutes
of operation. If condition is detected, outdoor unit will stop
(compressor and fan). Antishort cycle is initiated. If con
dition occurs 5 times within an hour, system will lock out.
To clear disconnect power to outdoor unit and restart. If

.

problem persists, replace inverter.

The inverter has detected a
PFC over current condi
tion. This would be caused
by a high load condition,
high pressure, or outdoor
fan failure.Outdoor control
will display the code when

Moderate /
Critical

the inverter has the error.
After 3 minutes, the inverter
will reset and the com

Issue: Possible issue is system running at high pres
sures. Check for high pressure trips or other alert codes in
room thermostat and outdoor control.

pressor will turn on again.
If it happens 10 times with
in a 60 minute rolling time
period, the OD control will
lock out operation of the
outdoor unit and display a
critical code.

Input current is approaching a high limit. Compressor
speed automatically slows. The control continues send

Compressor slowdown due
to high input current.

ing the inverter speed demanded by the thermostat. The
control sets indoor CFM and outdoor RPM to values ac
cording to demand percentage rather than the actual Hz.
Alarm is automatically cleared.

Page 34

XP25

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).

Table 6. Outdoor Control 7-Segment Display Alert Codes and Inverter LED Flash Codes

Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

Inverter LED Flash

Alert

Codes

E 440 13 1 flash 3 flashes Moderate

E 441 14 1 flash 4 flashes Moderate

E 442 N/A N/A N/A Critical

E 443 N/A N/A N/A Critical

E 600 N/A N/A N/A Critical

E 601 N/A N/A N/A Critical

Inverter
Code

Code (number of
flashes)

Red LED Green LED

®

thermostat.

Priority Alarm Description Possible Causes and Clearing Alarm

Heat sink temperature is
approaching limit. The
compressor speed auto
matically slows to reduce
heat sink temperature. The
control sets indoor CFM
and outdoor RPM to values
according to demand per
centage rather than the ac
tual Hz. Alarm is automatic
ally cleared.

Compressor slowdown due
to high compressor current.
Compressor current is ap
proaching limit. The com
pressor speed automatic
ally slows. The control sets
indoor CFM and outdoor
RPM to values according to
demand percentage rather
than the actual Hz. Alarm is
automatically cleared..

The top cap switch has
opened five times within
one hour. As a result, the
outdoor unit is locked out

Incorrect appliance unit
size code selected.

Compressor has been
cycled OFF on utility load
shedding.

Outdoor unit has been
cycled OFF on low temper
ature protection.

Issue: Feedback from supplier tear down of inverter in
dicates that the screws that hold the inverter to the invert
er board were loose causing poor contact between these
two components.

Corrective action: Tighten screws that hold the heat sink
to the inverter control board.

NOTE: Wait 5 minutes to all capacitor to discharge before
checking screws.

Issue: Possible issue is system running at high pres
sures. Check for high pressure trips or other alert codes in
room thermostat and outdoor control.

When compressor thermal protection sensor opens five
times within one hour, outdoor stops working. To clear,
disconnect power to outdoor unit and restart.

.

Check for proper configuring of unit size codes for out
door unit in configuration guide or in installation instruc
tions. If replacing inverter, verify inverter model
matches unit size. The alarm/fault clears after the cor
rect match is detected following a reset. Remove the
thermostat from the system while applying power and
reprogramming.

Load shedding function: Provides a method for a local
utility company to limit the maximum power level usage of
the outdoor unit. The feature is activated by applying 24
volts AC power to the L and C terminals on the outdoor
control.

Low temperature protection: Outdoor unit will not operate
when the outdoor temperature is at or below 4°F
(20°C). If the unit is operating and the outdoor temper
ature drops below 4°F (20°C), the unit continues to op
erate until the room thermostat is satisfied or the outdoor
temperature drops to 15°F (26°C). Outdoor unit ambi
ent sensor provides temperature readings.

Page 35

XP25

POWER-UP / RESET:

7-SEGMENT POWER-UP DISPLAY STRING

FIRMWARE VERSION: During initial power-up or reset, the
first item displayed is the outdoor control firmware version.
Example to the right shows firmware version 2.3.

UNIT TYPE: The next item displayed is the self discovery
unit type. AC = air conditioner and HP = heat pump. If the
unit type cannot be determined, three bars appear.

UNIT NOMINAL CAPACITY: The next item to be displayed
is the self-discovery unit nominal capacity. Valid capacities
are 24 for 2-ton, 36 for 3-ton, 48 for 4-ton and 60 for 5-ton
units. If the unit type cannot be determined, three bars ap
pear.

UNIT CODE: The next item to be displayed is the self discov
ery unit code. (may be a single character or two characters).
If the unit code cannot be determined, three bars appear.

UNIT CODE







UNIT TYPE, SIZE AND MODEL

NOT PROGRAMMED

2-TON HEAT PUMP, XP25-024

3-TON HEAT PUMP, XP25-036

4-TON HEAT PUMP, XP25-048

5-TON HEAT PUMP, XP25-060

.



OR



THROUGH



(These are just examples of firmware version, unit type,



FIRMWARE

VERSION

unit nominal capacity and unit codes.)

7-SEGMENT POWER-UP DISPLAY STRING EXAMPLE

.



UNIT

TYPE







OR







UNIT

CAPACITY

OR



UNIT

CODE

OR



.

IDLE MODE









2-TON AIR CONDITIONER, XC25-024

3-TON AIR CONDITIONER, XC25-036



4-TON AIR CONDITIONER, XC25-048



5-TON AIR CONDITIONER, XC25-060



Figure 17. Outdoor Control 7-Segment Unit Status Displays

Page 36

XP25

Table 7. Outdoor Control 7-Segment Unit Status Displays

Description Example of Display

Idle Mode: Decimal point flashes at 1 Hz

Soft Disabled: Top and bottom horizontal line and decimal point

flash at 1 Hz.

Factory Test Mode

Anti-Short Cycle Delay

Cooling Cycle: Shows current percentage of maximum cooling

capacity. Example to the right indicates a cooling demand of 50
percent and a outdoor fan speed of 700 RPM.

Idle Mode: Decimal point flashes at 1 Hz (0.5 second on, 0.5 second off).
Display OFF.

Soft Disabled: Top and bottom horizontal line and decimal point flash at 1
Hz (0.5 second on, 0.5 second off). Note - Control should be replaced.

All segments flashing at 2 Hz (unless error is detected) Note - Control
should be replaced.

The middle line flashes at 1 Hz for 2 seconds, followed by a 2-second dis
play of the number of minutes left on the timer (value is rounded up: 2 min.
1 sec. is displayed as 3). If activated, the anti-short cycle delay time remain
ing is displayed (default is 300 sec./5 min.).

The demand percentage is displayed first, followed by a pause, then the
outdoor fan speed and the ambient temperature.

   pause     pause   

Heating Pump Cycle: Shows current percentage of maximum

heating capacity. Example to the right indicates a heating de
mand of 33 percent and an outdoor fan speed of 600 RPM.

Defrost Mode: Shown only while in an active defrost.

Diagnostic recall: Shows the last 10 stored diagnostic error

codes.

Fault memory clears

Active error in outdoor control Idle mode: Show all active

error(s) codes.

Active error in run mode: Show current status and all active
error(s) codes.

Outdoor Ambient Temperature (OAT): Any time OAT is sensed
in operating range, value is displayed if unit is in diagnostic and
non-diagnostic modes.

Outdoor Coil Temperature (OCT): Any time OCT is sensed in
operating range, value is displayed if unit is in diagnostic mode
or manually enabled for non-diagnostic modes.

Following string is repeated if heat pump is active with outdoor fan speed
set at 600 RPM. Note -  - If available, displays outdoor ambient tempera
ture.

   pause     pause   

Following string is repeated if defrost is active.

  pause

If first error is    , second     pause     pause

   

Next codes (up to 10) are show using same method.

If there are no error codes stored:  pause    . After the fault memory
is cleared, the following is displayed with 0.5 seconds character ON / OFF
time:

    pause

Following display string is repeated if Error E 125 and E 201 are present:

    pause    

Following display string is repeated if Error E 440 is present while outdoor
fan speed at 700RPM:

    pause    

Following display string is repeated if cooling is active with outdoor fan
speed set at 650 RPM and OAT is 104

º

F:

   pause     pause     pause

Following display string is repeated if heat is active with outdoor fan speed
set at 550 RPM and OCT is 25ºF:

   pause     pause    pause

Liquid Line Temperature (LIQ): Any time LIQ is sensed in oper
ating range, value is displayed if unit is in diagnostic mode or
manually enabled for non-diagnostic modes.

Pump Down Mode: While the unit is in pump down mode,  
is displayed repeatedly. Errors are shown if they exist.

Following display string is repeated if cooling is active with outdoor fan
speed set at 650 RPM and LIQ is 105ºF:

   pause     pause     pause

Following display string is repeated:

  pause  

 

pause     pause   pause    

Page 37

XP25

PUSH-BUTTON OPERATION

Allows field access to Diagnostic, Fan, Defrost and Error Code Re
call modes.

Outdoor control must be in
IDLE mode (no heating or
cooling operation)

NOTE - See table 6 for explanation of codes.

To enter mode options, push and hold button next to 7seg
ment display until DASH symbol appears. Immediately re
lease the button. Once dash starts flashing, proceed to
next step.

Push and hold button until the selection stops flashing, then release button. The 7 seg
ment display shows the selected mode and the control performs the selected function.

Push and hold button until mode
selection displays on the 7seg

_

ment display (, ,    ,  or
). Immediately release the button,

proceed to next step.

_





Figure 18. Push-Button Operation

Unit Selection Code for Outdoor Control

If the single-character display shows three (3) horizontal lines, the unit selection code needs to be programmed. Press and hold the button until the  
menu option is displayed, release button. The singlecharacter display displays the selected mode per example in figure 17 on page 36. When the de
sired unit selection code appears, press and hold the button until it stops flashing, then release.

Unit Code Unit Type Unit Model







7









2-ton heat pump XP25-024

3-ton heat pump XP25-036

4-ton heat pump XP25-048

5-ton heat pump XP25-060

2-ton air conditioner XC25-024

3-ton air conditioner XC25-036

4-ton air conditioner XC25-048

5-ton air conditioner XC25-060

Idle mode — decimal flashes at 1 Hertz > 0.5 second ON, 0.5 second OFF. Idle mode is when the system is energized but no demand.

Display
Symbol or
Character

Displayed
during start-up
or power
recycling.

.

Display Fan Test and Display String Option

Display string shows outdoor control firmware version    > pause>   or   unit >pause>unit capacity in BTUs>pause >unit code.
If 3 horizontal bars are displayed during any sequence of this display string, it indicates that the specific parameter is not configured.

Idle mode — decimal flashes at 1 Hertz > 0.5 second ON, 0.5 second OFF.

 or  Indicates either cooling () or heating () mode and demand percentage.

 





Code displays when system is in defrost mode. To enter defrost mode, unit must be running in heating mode, outdoor ambient
must be below 65F and outdoor coil temperature must be below defrost termination temperature.

Control must be in Idle mode: To enter fan test option -  mode, push and hold button
until solid – appears, release button. Display begins flashing. Within 10 seconds, push

Indicates outdoor fan RPM speed.

 indicates that the display is show

ing the ambient temperature in F
(at the outdoor unit sensor).

 displayed during configuration

mode, indicates the option to display
coil and liquid line temperatures is
enabled.

and hold button until required symbol  displays, release button. Display begins flashing.
Within 10 seconds, push and hold button until display stops flashing, release button.
Control outputs DC voltage on PWM and COM terminals. Outdoor fan cycles ON for 10
minutes at 490 RPM. To exit test – Push and hold button until three horizontal bars dis
play. Release button, outdoor fan cycles OFF.

Control can be in Idle or demand mode: To enter display configuration option -  mode,
push and hold button until solid – appears, release button. Display begins flashing. Within 10

seconds, push and hold button until required symbol
gins flashing. Within 10 seconds, push and hold button until display stops flashing, release
button. Display shows error () code(s), ambient (), outdoor coil () and liquid () tempera
tures in Fahrenheit.

NOTE - If button is not pushed in the 10-second time period, the control exits the test mode. If
this occurs, test mode must be repeated.

 displays, release button. Display be

XP25

Page 38

Error Code Recall Mode (Note - control must be in idle mode)

To enter error code recall mode, push and hold button until solid  appears, then release button. Control displays up to 10 error codes
stored in memory. If     is displayed, there are no stored error codes.

To exit error code recall mode, push and hold button until solid three horizontal bars appear, then release button. Note - Error codes

are not cleared.

To clear error codes stored in memory, continue to push button while the 3 horizontal bars are displayed. Release button when solid 
is displayed.

Push and hold for one (1) second, release button. 7-Segment displays
    and exits error recall mode.

—

—

—







FIELD TEST MODE OPERATION

The field test mode allows the unit to be put into diagnostic
mode and allows the installer to perform multiple tests on the
control / unit.

Forced Defrost Mode

This mode is available for heat pump units only. This mode
can only be selected when the unit is in heating mode and
the ambient sensor is reading a temperature below 65ºF.

• When in this mode, the coil and ambient sensor

readings are shown on the 7-segment display.

• The control indicates an active defrost state.

• The menu mode automatically exits when forced defrost

is selected. The appropriate values are shown on the
7-segment display.

• The 7-segment display indicates defrost mode as

described in table 7.

• Forced defrost mode exits under the following

conditions:

A Defrost period expired
B Defrost termination temperature reached
C Heating demand satisfied
D Push button is pressed and released without

entering the menus

Diagnostic Mode

Diagnostic mode is only available when the system is idle or
during an active / suspended call for heating or cooling.
Diagnostic mode is terminated when the exit command is
given, the push button is pressed and released without
entering the diagnostic menu, or 10 minutes has passed,
whichever comes first.

When this mode is selected, all installed temperature sensor
valves (non-open and non-short) is shown on the 7-segment
display. The following system status codes are displayed:

• Heating / Cooling

• Defrost Status

• Percentage demand operation

• Outdoor fan RPM

• Active error codes

Outdoor Fan Mode

This mode is only available while the system is in idle mode.
This mode can be exited with the proper command or after
10 minutes has passed.

In this mode, the control energizes the outdoor fan at the
highest speed. The control continuously displays the fan
RPM on the 7-segment display.

PUMP DOWN MODE OPERATION

1. Turn room thermostat OFF.

2. Install a set of refrigerant gauges on the system to
monitor the pressure.

NOTE - All operation monitoring devices: high pressure
switch, low pressure switch and compressor internal
vacuum protection remain active in the system. This
prevents the compressor from recovering all the system
refrigerant into the outdoor unit.

NOTE - If the pump down jumper is in the ON position during
power-up, it is ignored.

3. Move the Pump Down jumper (see page Page 75 for
location) from the OFF position to the ON position.

PUMP DOWN

ON

OFF

PUMP DOWN

ON

OFF

Figure 19. Pump Down Jumper

4. Shut off the liquid line service valve to stop the flow of
refrigerant into the indoor coil.

5. After a three-second delay, the compressor and outdoor
fan increases speed up to 100% capacity. (Indoor fan
remains OFF.)

6. Monitor the low-side pressure at the outdoor unit. The
internal vacuum protection in the compressor and/or
one of the pressure switches prevent full recovery of all
of the refrigerant into the outdoor unit. When the system
reaches this condition,close the suction line service
valve and move the Pump Down Jumper to the OFF
position.

NOTE - The outdoor control stays in pump down mode for
five minutes, after which the outdoor control initiates a
compressor shutdown sequence.

7. Use a refrigerant recovery machine to recover the
remaining refrigerant on the indoor side of the system.

Page 39

XP25

Table 8. Field Test, Diagnostic Recall and Program Menu Options

Display

No Change - idle
(*)

Solid . Enter or exit field test and program mode.

Solid  Puts unit in diagnostic mode. (Displays ambient, coil, liquid sensor temperatures and any active error codes.)

Solid  Clears error history (**)

Solid  Enter diagnostic recall mode. Displays up to 10 error codes in memory.

Solid  Start forced defrost test

Solid  Starts outdoor fan.

String   Enter unit code programming.

*No change indicates the display continues to show whatever is currently being displayed for normal operations.

**Note - Once the error history is deleted, it cannot be recovered. After the history is deleted, the unit resets itself.

Display and action (normal operation)

No Change - idle (*)

Table 9. Normal Operation Character Display String

Display

.




Display and action (normal operation) Display and action (configuration and test mode)

Idle mode — decimal flashes at 1 Hertz > 0.5 second ON, 0.5 second OFF

Cooling operation. Shows  and the cooling demand percentage. Example:    pause     pause   

Fan RPM. Shows  and the current fan RPM. Example:    pause     pause   

  in the display string represents the active error code or codes in the outdoor unit.

Example:    pause     pause     pause     pause    pause

  in the display string represents the outdoor ambient temperature in F at the outdoor sensor on the outdoor unit.

Example:    pause     pause   

 If enabled,  in the display string represents the outdoor coil temperature in F at the sensor on the outdoor unit.

Example:    pause     pause    pause    pause. Air conditioning units do not require an outdoor coil sensor.
A 10K resistor, across pins 5 and 6 on the outdoor control sensor harness, prevents false outdoor coil sensor codes. The 10K
resistor causes the 7-segment display to show a constant 77ºF coil (c) temperature value.

 If enabled,  in the display string represents the outdoor liquid line temperature in F at the sensor on the outdoor unit.

Example:    pause     pause    pause    pause pause     pause

 

  displays when system is in pump down mode.

TYPICAL 7-SEGMENT ACTIVE COOLING OR HEATING DEMAND DISPLAY STRING

 

COOLING AT

50% DEMAND

BY DEFAULT, COOLING OR HEATING, DEMAND, OUTDOOR FAN RPM, ACTIVE ERROR CODES

* Air conditioning units do not require an outdoor coil sensor. A 10K resistor, across pins 5 and 6 on the outdoor control sensor harness, prevents
false outdoor coil sensor codes. The 10K resistor causes the 7-segment display to show a constant 77ºF coil (c) temperature value.

OUTDOOR

FAN RPM

AND OUTDOOR AMBIENT TEMPERATURE ARE DISPLAYED.





CODE (IF PRESENT)



ACTIVE ERROR

 

OUTDOOR

AMBIENT AIR

TEMP

MANUALLY ENABLED. IF SYSTEM POWER IS RECYCLED, DISPLAY

STRING REVERTS BACK TO DEFAULT (SEE FIGURE 21 TO ENABLE)





OUTDOOR

COIL TEMP(*)

OUTDOOR COIL AND LIQUID LINE TEMPERATURES CAN BE





OUTDOOR LIQUID

LINE TEMP





Figure 20. Typical 7-Segment Demand Display String

Page 40

XP25

How to enable liquid line temperature information on a 7-segment display

Both coil and liquid line temperatures can be enabled for display
either during normal demand operation or while in idle mode.

NOTE - IF SYSTEM POWER IS RECYCLED, DISPLAY STRING

REVERTS BACK TO DEFAULT. THE ABOVE PROCEDURE

NEEDS TO BE REPEATED TO ENABLE OUTDOOR COIL AND

LIQUID LINE TEMPERATURE INFORMATION. ALL TEMPER

ATURES ARE DISPLAYED IN FAHRENHEIT.

Yes

To enable temperature display, push
and hold button next to 7-segment
display until dash symbol appears
and immediately release button.
Once dash starts flashing, proceed
to next step.

Push and hold the button until the solid

 appears on the 7-segment display.

Then, immediately release the button.

During thermostat demand of the outdoor control, the 7-segment display shows the cooling or heating (percent demand), fan RPM, error codes if present, and
outdoor ambient, Coil and liquid line temperatures need to be manually enabled to be displayed.





PERCENTAGE OF

MAXIMUM CAPACITY

NOTE - The coil and liquid line temperature readings are temporarily shown on the outdoor 7-segment display when the iComfort Wi-Fi® diagnostic screen is
accessed.



FAN RPM



_



 

ACTIVE ERRORS

Outdoor control is either in IDLE

mode or heating / cooling

demand)

_



OUTDOOR

ONLY

AMBIENT

Push and hold button until the
flashing
release button. The display shows
the coil and liquid line temperature if
there is an active demand running.

 stops flashing then









OUTDOOR COIL

TEMP (*)

Wait until unit returns
to a active demand or

idle mode.





 

OUTDOOR LIQUID

LINE TEMP



Figure 21. Enabling Liquid Line Temperature Information

Page 41

XP25

Configuring Unit

When installing a new or replacement outdoor control, the unit selection code may have to be manually assigned using the
7-segment display and push button on the control. The unit code sets unit type, capacity and outdoor fan RPM.

Configuring Unit Selection Code

Power-up - Unit selection code (two-digit number) displayed

represents unit size code (outdoor unit capacity).
During initial power-up, firmware version, unit type, unit capacity
and unit selection code appears on the 7-segment display.

If three horizontal bars are shown in the 7-segment display
during power-up, the outdoor control did not store the last
configuration setting. If this happens, the configuration se
quence for that setting must be repeated.

−

−

−

To enter unit selection code,
push and hold button next
7-segment display until dash
symbol appears and
immediately release button.
Once dash starts flashing,
proceed to next step.

Push and hold button until the solid
 sequence is displayed on the
7-segment display, then
immediately release the button. This
configuration sequence allows the
installer to choose the unit selection
code (number combination) that
matches the outdoor unit type and
inverter.

Press and hold the button during
the  cycling display.

NOTE: The  sequence repeats
5 times. If a selection is not made,
the control returns to idle mode.

Yes

_

_

UNIT SELECTION

CODE



NOT

SELECTED

Outdoor control is in IDLE mode

(No heating or cooling demand)



No

Turn room thermostat

to OFF

1. When the correct unit section code is displayed, release but
ton immediately. [Display begins flashing]

2. Push and hold button until selection stops flashing during
one of the three cycles. [Release push button]

3. If selection is not made during those three cycles the control
returns to idle mode.

UNIT SELECTION

CODES

2

2-TON HEAT PUMP (XP25-024)

4

3-TON HEAT PUMP (XP25-036)

6

4-TON HEAT PUMP (XP25-048)

7

5-TON HEAT PUMP (XP25-060)

9

2-TON AIR CONDITIONER (XC25-024)

11

3-TON AIR CONDITIONER (XC25-036)

13

4-TON AIR CONDITIONER (XC25-048)

14

5-TON AIR CONDITIONER (XC25-060)

UNIT

SELECTED

NOT

SELECTED

SELECTED

If three horizontal bars display in any
part of the 7-segment display string
during power-up, the outdoor
control did not store the unit
selection code. If this occurs, the
configuration sequence for that
section of the display string must be
repeated.

The outdoor control stores the unit type, automatically exits the con
figuration mode and resets.

EXAMPLE 7-SEGMENT DISPLAY STRING

−



−

−

.

FIRMWARE

VERSION





UNIT

TYPE





UNIT

CAPACITY



UNIT

CODE



(NO DEMAND)

.

IDLE MODE

Figure 22. Configuring Unit Selection Code

XP25

Page 42

Reconfiguring Outdoor Control using
iComfort Wi-Fi

If any component of the HVAC system is changed, ( e.g. an
outdoor sensor is replaced), reconfigure the system. To
begin reconfiguring a system, select the Setup tab.

®

Thermostat

System Overview

Refer to the iComfort Wi-Fi® Thermostat Installer Guide for
configuration procedures.

IMPORTANT

Some scroll compressors have internal an vacuum
protector that unloads the scrolls when suction pressure
drops below 20 psig. A hissing sound is heard when the
compressor is running unloaded. Protector resets when
low pressure in system is raised above 40 psig. DO NOT
REPLACE COMPRESSOR.

• Low pressure switch status

• Compressor top cap switch status

• Liquid line temperature

• Outdoor ambient temperature

• Coil temperature

• Time since last defrost

• Calibration delta T

• Current delta T

• Outdoor fan RPM

• Compressor active alarm

• Compressor Hz

• Inverter compressor short cycle

• Heat sink temperature

Installer Test

The outdoor control provides the following functions:

• Demand defrost algorithm

• Field-selectable defrost termination temperatures

through the thermostat interface

• Internal switching of outputs

• Anti-short-cycle delay (adjustable through the

thermostat interface

• Five-strike lockout function

• Ambient (RT13), coil (RT21) and liquid line (RT36)

temperatures monitoring and protection

COMPRESSOR PROTECTION — FIVE-STRIKE
LOCKOUT FUNCTION

The five-strike lockout function is designed to protect the
unit's compressor from damage. The five-strike feature is
used for high (S4) and low (S87) pressure switch trips.

Resetting Five-Strike Lockout

Once the condition has been resolved, power to the outdoor
control R terminal must be cycled OFF.

Diagnostic Information

The following diagnostic information is available through the
thermostat user interface. Refer to the Wi-Fi
System Setup Guide.

®

Installer

• Compressor anti-short cycle delay timer status

• Cooling rate

• Heating rate

• Compressor shift delay timer status

• Defrost status

• High pressure switch status

Verify the proper operation of the system by running the
Installer Test feature through the thermostat interface. Refer
to the iComfort Wi-Fi

®

Installer's System Setup Guide.

Defrost Function

The outdoor unit control measures differential temperatures
to detect when the system is performing poorly because of
ice build-up on the outdoor coil. The controller self-calibrates
(see figure 33) when the defrost system starts and after each
system defrost cycle. The outdoor unit control monitors
ambient temperature, outdoor coil temperature, and total
run-time to determine when a defrost cycle is required. The
coil temperature sensor is designed with a spring clip to
secure the sensor to the outside coil tubing. The location of
the coil sensor is important for proper defrost operation (see
figure 59 on page 77 for location of coil sensor).

NOTE - The outdoor unit control accurately measures the
performance of the system as frost accumulates on the
outdoor coil. This typically translates into longer running time
between defrost cycles as more frost accumulates on the
outdoor coil before the outdoor control initiates defrost
cycles.

DEFROST OPERATING MODES

The outdoor control has three operational modes:

• Defrost calibration (see figure 33)

• Operation

• Defrost test

DEFROST TERMINATION TEMPERATURES

The defrost termination temperature setting selections (50,
70, 80, 90, and 100°F) are available through the thermostat
interface. The factory default setting is 50°F (10°C).

NOTE - Colder climates may require a higher discharge
termination temperature setting to maintain a clear coil.

Page 43

XP25

COMPRESSOR SHORT-CYCLING DELAY

The outdoor control protects the compressor from:

reduces sounds that occur while the unit is cycling in and out
of the defrost mode.

• Short-cycling (five minutes) when there is initial power

up

• Interruption in power to the unit

• Pressure or sensor trips

• Delay after demand is removed.

The delay is set by default for 300 seconds (five minutes) but
can be changed through the thermostat interface.

Available settings are 60, 120, 180, 240 and 300 seconds.

COMPRESSOR SHIFT DELAY
The outdoor control has a field-selectable option (ON or

OFF), selected through the thermostat interface, which

Table 10. Heat Pump Cooling Operational Range

Temperature

C° F°

Room thermostat controls operation of outdoor unit.

Above

(-) 20°C

At or Below

(-) 20°C

Temperature

C° F°

Above

(-) 4°F

At or Below

(-) 4°F

NOTE - Below 65°F (18.3°C) the liquid line temperature sensor controls the outdoor fan speed (RPM)
to maintain a liquid line temperature between 58°F (14.4°C) and 55°F (12.8°C).

NOTE - Minimum fan RPM is 300.
Outdoor unit cooling operation stopped by low ambient temperature protection (Status Code 601).

Table 11. Heat Pump Heating Operational Range

Room thermostat controls operation of outdoor unit.

* When enabled, there is a 30-second compressor shift

delay which de-energizes the contactor output and ECM
fan outputs. After the delay expires, the contactor and
ECM, fan outputs are energized.

* When disabled, the reversing valve is shifted by

de-energizing the outputs.

Outdoor Temperature Operational Range

Use the chart below to determine the operational limits in
reference to outdoor temperatures.

Event

Event

Above

(-) 26°C

At or Below

(-) 26°C

Above

(-) 15°F

At or Below

(-) 15°F

NOTE - If the outdoor unit is operating and the outdoor ambient temperature drops below -4°F
(-20°C), the unit continues to operate until the room thermostat demand is satisfied or the outdoor
temperature drops to -15°F (-26°C). If the outdoor unit stops running while the temperature is below

-4°F (-20°C), the unit remains OFF until outdoor temperature rises above -4°F (-20°C),
Outdoor unit heating operation stopped by low ambient temperature protection (Status Code 601).

NOTE - Room thermostat "Low Balance Point" minimum setting is -15°F (-26°C).

NOTE - If system conditions are outside the specified ranges, the outdoor control may reduce, terminate, or prevent system
operation.

Page 44

XP25

Maintenance

Outdoor Unit

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:

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 factory-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 amp draw on outdoor fan motor.

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.

3. Check condensate line and clean if necessary.

Locations with Possibility of Heavy Snow or

Freezing Rain Accumulation

Heavy snow and/or freezing rain can interfere with the
performance of the outdoor fan assembly. Lennox
recommends use of the optional snow guard (X8782) in
these areas.

Outdoor Coil

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).

• Outdoor Coil — The outdoor coil may be flushed with a

water hose.

• Outdoor Coil (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
determine the 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 factory-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 CFM.
Refer to the unit information service manual for pressure
drop tables and procedure.

4. Check all wiring for loose connections.

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

6. Check amp draw on blower motor.

Indoor Coil

1. Clean coil if necessary.

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

Figure 23. Snow Guard Top Cover — X8782

SunSource® Home Energy System

This Dave Lennox Signature® Collection heat pump is
factory-equipped with components that make it SunSource
Solar-Ready. These units can be matched with solar
modules and other optional equipment so that they can
become part of a SunSource

Units can be upgraded for use with solar equipment at the
time of installation or in the future.

Solar energy is first used to meet cooling/heating demands.
When the outdoor unit is not operating, the system powers
lighting, appliances and other electronic devices in the
home. Any surplus power is sent back to the utility company
for a possible credit. Check with your local utility company for
availability.

®

Home Energy System.

®

Page 45

XP25

Typical Unit Wiring Diagrams

Figure 24. Typical Unit Wiring (XP25-024 and -036)

Page 46

XP25

Figure 25. Typical Unit Wiring (XP25-048 and -060)

Page 47

XP25

NOTE - For more information on Load Shedding, see Electrical on page 24.

Figure 26. Load Shedding Feature Wiring Diagram

Page 48

XP25

Factory Wiring Diagrams

INVERTER

REACTOR

INVERTER

CONTROL

OUTDOOR

Figure 27. Typical Factory Wiring (XP25-024 and -036)

Page 49

XP25

REACTOR

INVERTER

INVERTER

NOISE FILTER

INVERTER

CONTROL

OUTDOOR

Figure 28. Typical Factory Wiring (XP25-048 and -060)

Page 50

XP25

Unit Sequence of Operations

The following figures illustrate the overall unit sequence of operation along with the operation of various pressure switches and
temperature sensors. The figures also illustrate the use of the compressor anti-short-cycle function in relation to unit Status,
unit Fault and lock out LED Codes and unit system operation interactions.

On 24 VAC power-up or outdoor reset, the outdoor control shall perform the follow
ing tasks:

1. Start the anti-short cycle 3-minute delay in the outdoor control.

2. Check status of the temperature sensor and pressure devices.

3. If the outdoor control does not detect any error codes, outdoor control sends 24 volts

out on the CNTCTR terminals to pull in the contactor coil.
(Note - These checks take about 60 seconds.)

4. The contactor contacts pull IN and main power is applied to the compressor inverter.

System

Idle

No

Room

Yes

All

switches

closed and

sensors in

operating

range?

Thermostat

Demand

Heating

Yes

Heating or

Cooling

Emer
gency

Heat Se

lected?

No

Yes

Balance

Region

Above the Low BP

or Not Applicable

Go To Primary

Heat Pump

Heating

Go To

Modulat

ing Heat

Pump

Go To Auxiliary

Below Low

BP

Point

Heat

Heating

No

Check for status or

fault codes in outdoor

control or room ther

mostat (Note - Refer to

low pressure and high

pressure switch flow

charts for sequence of

operation).

No

Cooling

All

switches

closed and

sensors in

operating

range?

Yes

Go To
Modu

lating

Cooling

Figure 29. 24 VAC Power-Up or Outdoor Reset

Page 51

XP25

On 24 VAC power-up or outdoor reset, the outdoor unit control shall perform the following tasks:

1. Start the anti-short cycle 3 minute delay in the outdoor control.

2. Check status of the temperature sensor and pressure devices.

3. If the outdoor unit control does not detect any error codes, it sends 24 volts out on the CNTCTR terminals to pull
in the contactor coil. (Note - These checks take about 60 seconds).

4. The contact(s) of the contactor pull IN and main power is applied to the compressor inverter.

From idle mode

No

Room thermostat is sending a heating percentage of maximum
capacity demand to the main control board in the outdoor unit.

Yes

Yes

All switches closed and

sensors in operating

range.

Yes

Yes

Outdoor Control

1. Sends a demand to the compressor inverter
to start and run the compressor up to the re
quested pumping capacity (Frequency in
Hertz).

2. Outputs a DC voltage on the FAN PWM and
COM terminals to start and run the outdoor
fan motor at the desired RPM.

3. Sends a communication signal to the indoor
unit to start and run the supply fan motor at
the demand air volume(CFM).

4. Energizes the on-board reversing valve re
lay to outputs 24 volts to the reversing valve.

No

No

Check for status or fault
codes in outdoor control
or room thermostat.
(Note - Refer to low
pressure and high pres
sure switch flow charts
for sequence of opera
tion.)

Diagnostics Screen

1. View the Heat PUMP screen for
current compressor frequency in
hertz.

2. View the OUTDOOR CONTROL
7-Segment display to read the
RPM of the outdoor fan motor.

3. View the AIR HANDLER screen
for actual CFM of the indoor
blower motor.

Figure 30. Heat Pump Mode

Page 52

XP25

From modu

lating heat

pump heat.

Heat pump ran for

at least 30 minutes?

Yes

Defrost in the last 30

minutes?

Yes

Auxiliary heat is
used to satisfy all
heat calls during
heat pump lock
out.

No

No

Back to modulating

heat pump heat.

Go to auxiliary

heat.

Figure 31. Transition to Auxiliary Heat

Page 53

XP25

Auxiliary heat (while

demand exists)

Dual Fuel?

Yes

Turn off heat pump.

Heat only using gas

heat.

No

Emergency

heat selected?

No

Balance

point region

All sensors closed

and within operating

range?

Yes

Yes

No

Balance

Balance

point region

point region

Check for status or

fault codes in out

door control

Go to auxiliary

heating.

Above the low balance point

Go to primary heat

pump heating.

Return to

modulating

heat pump

heat.

Figure 32. Auxiliary Heat

XP25

Page 54

Heat pump control monitors mode
of operation through outdoor
ambient temperature, outdoor coil
temperature and compressor
run-time to determine when a
defrost cycle is required.

Note - No system alert codes can
be active during defrost
calibration.

Defrost Calibration

Coil sensor detects temperature below 35°F {2°C} during
either initial power-up, after loss of power or after cooling
mode, a sacrificial defrost is used to ensure there is a clear
coil before attempting calibration.

Coil sensor

below 35°F {2°C}

NO

No attempt
to calibrate.

Notes:

When the HP enters defrost, the thermostat runs
auxiliary heat with the HP, stopping the auxiliary
heat when defrost ends.

Demand Mode

After the initial calibration, the outdoor control
disables the defrost mode for 30-34 minutes in
order to avoid unnecessary defrosts. Beyond
this timing period, both the ambient coil
sensors are continuously monitored. If the coil
temperature is below 35°F (2°C) and the cal
ibration delta is reached or accumulated com
pressor run-time is more than six (6) hours, a
defrost is to be initiated.

YES

Accumulated compressor run-time while outdoor
coil temperature sensor input is below 35°F (2°C)

30-35 minutes

compressor

run-time

YES

Defrost Mode

Initiate a defrost (Turn off outdoor fan, energize reversing
valve and increase compressor to 100% capacity). Monitor
coil temperature sensor input and accumulated defrost time.

How did defrost

terminate?

NO

Continue to
accumulate
run-time.

NO

Coil temperature sensor input
reached specified defrost ter
mination temperature as set
on outdoor control.

YES

Calibration Attempted

(Unit Running in Heat Mode)

Calibration

Defrost for 14 minutes without
the coil temperature sensor in
put reaching defrost termina
tion temperature as set on out
door control.

NO

Figure 33. Defrost Calibration and Defrost Mode Sequence of Operations (All Versions)

Page 55

XP25

Component Testing

Section Table of Contents

High and Low Pressure Switch Operation, Checkout and

Status / Error Codes 56...........................

Reversing Valve Operation, Checkout and Status / Error

Codes 60.......................................

Compressor Operation, Checkout and Status / Error

Codes 62.......................................

Compressor Sound Cover 65......................

Charge Compensator (XP25-024-230-XX and

XP25-048-230-XX only) 66........................

Discharge Muffler (Heat Pumps only) 66............

Liquid Line Bi-Flow Filter Drier (Heat Pumps only) 67.

Check Expansion Valve (Heat Pumps only) 68.......

Top Cap Switch Operation, Checkout and Status / Error

Codes 70.......................................

Reactor Operations, Checkout and Status /

Error Codes 71..................................

Line Filter (Electromagnetic Compatibility Circuit - EMC)
Operations, Checkout and Status / Error Codes 71...

Outdoor Fan Operation and Checkout 72...........

Ferrites 74......................................

Outdoor Control Operation, Checkout and Status / Error

Codes 75.......................................

Unit Sensor Operations, Checkout and Status / Error

Codes 76.......................................

Variable-Capacity Inverter Control Operation, Checkout

and Status / Error Codes 79.......................

Emergency 24VAC Operation 84...................

High and Low Pressure Switch Operation, Checkout and Status / Error Codes

OPERATION :

The unit's pressure switches (LO PS - S87 and HI PS - S4) are factory-wired into the control on the LO-PS and HI-PS
terminals, respectively.

Low Pressure Switch (LO-PS) — See figure 35 for low pressure switch sequence of operation.

High Pressure Switch (HI-PS) — See figure 36 for high pressure switch sequence of operation.

Pressure Switch Event Settings

The following pressures are the auto-reset event value triggers for low and high pressure thresholds:

• High Pressure (auto-reset) - trip at 590 psig; reset at 418.

• Low Pressure (auto-reset) - trip at 40 psig; reset at 90.

CHECKOUT

Using a multimeter set to ohms with the terminals disconnected from the control board, check the resistance between the
two terminals of the pressure switch. If the resistance reading is 0 ohms, the switch is closed.

S4
HIGH
PRESSURE
SWITCH

Figure 34. Verifying High Pressure and Low Pressure Switch Operation

S87
LOW
PRESSURE
SWITCH

XP25

Page 56

Y1 DEMAND

LOW

PRESSURE

SWITCH (S87)

CLOSED

CONTACTOR

ENERGIZED

INITIAL TRIP

SWITCH IS

IGNORED FOR

90 SECONDS

OPEN

OPEN

CONTACTOR

DE-ENERGIZED

ANTI-SHORT

CYCLE TIMER

BEGINS

INCREMENT

5-STRIKE

COUNTER

LED ALERT

CODE / OR

MODERATE

ALERT 410

DISPLAYED

LOW

PRESSURE

SWITCH (S87)

1. The thermostat terminates demand when the contactor is

CLOSED

SWITCH IS CLOSED OR OUTDOOR

AMBIENT TEMPERATURE IS 15ºF

OR BELOW

3

de-energized. If demand is satisfied when alarm is not active, the
5-strike counter resets.

2. Lockouts can be reset by cycling power off to the outdoor control

(A175) R terminal.

3.

The low pressure switch is ignored by the system when the out
door temperature is below 15°F.

5-STRIKE

COUNTER

REACHES 5

1

WITHIN A SINGLE

Y1 DEMAND

LOW

PRESSURE

SWITCH (S87)

LOCKOUT

SERVICE

REQUIRED

OPEN

CLOSED

LED ALERT

CODE / OR

CRITICAL

ALERT 411

DISPLAYED

LED ALERT
CODE / OR

MODERATE

ALERT 410

DISPLAYED

SERVICE

REQUIRED

2

NORMAL

OPERATION

ANTI-SHORT

CYCLE TIMER

ENDS

CONTACTOR

ENERGIZED

LOW

PRESSURE

SWITCH (S87)

2

WAITING FOR

PRESSURE
SWITCH TO

CLOSE

CLOSED

Figure 35. Low Pressure Switch (S87) Sequence of Operation (All Versions)

XP25

Page 57

Y1 DEMAND

OPEN

HIGH

PRESSURE

SWITCH (S4)

OPEN

CONTACTOR

DE-ENERGIZED

ANTI-SHORT

CYCLE TIMER

BEGINS

INCREMENT

5-STRIKE

COUNTER

1

CLOSED

HIGH

PRESSURE

SWITCH (S4)

1. The thermostat terminates demand when the contactor is

TOP CAP

SWITCH (S173)

CLOSED

CLOSED

de-energized. If demand is satisfied when alarm is not active, the
5-strike counter resets.

2. Lockouts can be reset by cycling power off to the outdoor control

(A175) R terminal.

5-STRIKE

COUNTER

REACHES 5

WITHIN A SINGLE

Y1 DEMAND

CONTACTOR

ENERGIZED

SERVICE

REQUIRED

2

OPEN

LED ALERT
CODE / OR

MODERATE

ALERT 412

DISPLAYED

ANTI-SHORT

CYCLE TIMER

ENDS

HIGH

PRESSURE

SWITCH (S4)

WAITING FOR

PRESSURE
SWITCH TO

CLOSE

CLOSED

CLOSED

HIGH

PRESSURE

SWITCH (S4)

LOCKOUT

LED ALERT

CODE / OR

CRITICAL

ALERT 413

CLEARED

MODERATE

DISPLAYED

LED ALERT
CODE / OR

ALERT 412

SERVICE

REQUIRED

2

NORMAL

OPERATION

Figure 36. High Pressure Switch (S4) Sequence of Operation (All Versions)

Page 58

XP25

High and Low Pressure Switch Errors

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).
Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

Alert

Codes

E 410 Moderate

E 411 Critical

E 412 Moderate

E 413 Critical

Table 12. Outdoor Control 7-Segment Display Alert Codes - High and Low Pressure Switches

®

thermostat.

Priority Alarm Description Possible Causes and Clearing Alarm

Unit pressure is below the lower limit. The system is shutdown. The low pressure switch

The outdoor unit low pressure
switch has tripped.

The low pressure switch has tripped
5 times within one hour. As a result,
the outdoor unit is locked out

The outdoor unit high pressure
switch has opened.

The high pressure switch has
opened 5 times within one hour. As
a result, the outdoor unit is locked
out

.

.

opens at 25PSIG and closes at 40PSIG. Confirm that the system is properly charged
with refrigerant. Check TXV, indoor unit blower motor, dirty filters or clogged refrigerant
filter. Confirm that the evaporator coil is clean. The alarm clears after the pressure
switch opens or after a power reset.

Low pressure switch error count reached 5 strikes. The low pressure switch opens at
40PSIG and resets at 90PSIG. Confirm that the system is properly charged with refri
gerant. Check for clogged TXV, blockage to indoor unit blower motor, dirty filters or
clogged refrigerant filter. Confirm that the evaporator coil is clean. The alarm clears
after a power reset.

Unit pressure is above the upper limit. System is shut down. The high pressure switch
opens at 590PSIG and closes at 418PSIG. Confirm that the system is properly charged
with refrigerant. Check for clogged TXV, blockage to indoor unit blower motor, clogged
refrigerant filter. Confirm that the outdoor unit is clean. The alarm clears after the pres
sure switch closes or a power reset.
For heating, indoor CFM may be set too low. For zoning system, zone CFM may be set
too low.

Unit pressure is above the upper limit. System is shut down. The high pressure switch
opens at 590PSIG and closes at 418PSIG. Confirm that the system is properly charged
with refrigerant. Check for clogged TXV, blockage to indoor unit blower motor, clogged
refrigerant filter. Confirm that the outdoor unit is clean. The alarm clears after the pres
sure switch closes or a power reset.
For heating, indoor CFM may be set too low. For zoning system, zone CFM may be set
too low.

Page 59

XP25

Reversing Valve Operation, Checkout and Status / Error Codes

OPERATION:

The reversing valve switches the system between cooling and heating modes. By switching the flow of refrigerant, the
heat pump can incorporate the functions of cooling in the summer and heating in the winter. The valve consists of a main
body and a solenoid coil.

Note - The reversing valve solenoid is energized in the cooling mode.

Figure 37. Reversing Valve (L1)

CHECKOUT:

Using a multimeter set to ohms, with the solenoid terminals disconnected from the outdoor unit’s control, check the
resistance between the two terminals of the reversing valve solenoid. If the resistance reading is 0 ohms or infinite,
replace solenoid coil.

Figure 38. Reversing Valve Checkout

Page 60

XP25

IMPORTANT - ENSURE NEW REVERSING VALVE IS INSTALLED EXACTLY AS ORIGINAL
VALVE.

SOLENOID

TO COMPRESSOR

DISCHARGE LINE

LINE TO OUTDOOR

SUCTION LINE (TO

COMPRESSOR)

IMPORTANT - CONFIRM CORRECT CONNECTIONS OF
REFRIGERANT LINES TO REVERSING VALVE BEFORE
BRAZING IN VALVE.

COIL

VAPOR LINE (TO SERVICE VALVE)

REVERSING VALVE

OPERATION

1. WHEN THE SOLENOID IS ENERGIZED (ON), THE
EVAPORATOR (INDOOR COIL – E) REFRIGERANT
PRESSURE IS DIRECTED TO THE SUCTION (S) BACK
TO THE COMPRESSOR.

2. WHEN THE SOLENOID IS DE-ENERGIZED (OFF),

REFRIGERANT PRESSURE IS DIRECTED FROM THE
CONDENSER (OUTDOOR COIL – C) TO THE SUCTION
(S) BACK TO THE COMPRESSOR.

Figure 39. Typical Reversing Valve Components and Operation

STATUS CODE:

Diagnostic screen in room thermostat indicates when reversing valve is ON.

ERROR CODES:

There is no feedback from the reversing valve to the outdoor control therefore no error codes is displayed on the outdoor
control or iComfort Wi-Fi

®

room thermostat. (NOTE - If the reversing valve does not operate as designed, the system is

shut down by other controls.)

Page 61

XP25

Compressor Operation, Checkout and Status / Error Codes

OPERATION:

The compressor is a 380VAC three-phase variable-capacity scroll compressor that is approved for use with HFC410A
refrigerant. The compressor, when connected to an inverter, is capable of operating in a running frequency range from 22
hertz up to a maximum of 70 Hertz (maximum hertz is dependent on compressor size). The compressor speed is determined
by demand from the room thermostat.

CHECKOUT:

Figure 40. Compressor Operation, Checkout and Status/Error Codes

IMPORTANT: If compressor replacement is required, remove the compressor through the top of the unit. Removal through

the access panel is not possible.

STATUS CODES:

When the compressor is running, the 7segment display on the outdoor control displays (strings) the room thermostat
demand to the compressor as a percentage. (Example: C 5 0 – compressor is running at 50% of maximum speed.)

XP25

Page 62

ERROR CODES:

Table 13. Outdoor Control 7-Segment Display Alert Codes - Compressor

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).
Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

Inverter LED Flash

Alert

Codes

E 430 26 2 flashes 6 flashes

E 433 29 2 flashes 9 flashes

E 439 12 1 flash 2 flashes Moderate

E 440 13 1 flash 3 flashes Moderate

E 441 14 1 flash 4 flashes Moderate

Inverter
Code

Code (number of
flashes)

Red
LED

Green LED

®

thermostat.

Priority Alarm Description Possible Causes and Clearing Alarm

If condition is detected, outdoor unit com
pressor and fan stop. Antishort cycle is initi
ated. If condition occurs 10 times within an

Moderate /
Critical

Moderate /
Critical

Compressor start failure.

The inverter has detected a com
pressor over-current condition

Compressor slowdown due to high
input current.

Heat sink temperature is approach
ing limit. The compressor speed
automatically slows to reduce heat
sink temperature. The control sets
indoor CFM and outdoor RPM to
values according to demand per
centage rather than the actual Hz.
Alarm is automatically cleared.

Compressor slowdown due to high
compressor current. Compressor
current is approaching limit. The
compressor speed automatically
slows. The control sets indoor CFM
and outdoor RPM to values accord
ing to demand percentage rather
than the actual Hz. Alarm is auto
matically cleared..

hour, system is locked out.
Indicates poor connection at compressor har
ness, improper winding resistance, locked com
pressor rotor, or flooded compressor.
To clear, disconnect power to outdoor unit and
restart.

Error occurs when compressor peak phase
current is greater than 28A. Inverter issues
code 14 first and slows down to try to reduce
the current. If the current remains high, out
door unit compressor and fan stop. Antishort

.

cycle is initiated. If condition occurs 5 times
within an hour, system is locked out. To clear
disconnect power to outdoor unit and restart.

Input current is approaching a high limit. Com
pressor speed automatically slows. The control
continues sending the inverter speed deman
ded by the thermostat. The control sets indoor
CFM and outdoor RPM to values according to
demand percentage rather than the actual Hz.
Alarm is automatically cleared.

Issue: Feedback from supplier tear down of
inverter indicates that the screws that hold the
inverter to the inverter board were loose caus
ing poor contact between these two compon
ents.

Corrective action: Tighten screws that hold
the heat sink to the inverter control board.

NOTE: Wait 5 minutes to all capacitor to dis
charge before checking screws.

Issue: Possible issue is system running at high
pressures. Check for high pressure trips or oth
er alert codes in room thermostat and outdoor
control.

E 600 N/A N/A N/A Critical

Compressor has been cycled OFF
on utility load shedding.

Page 63

Load shedding function: Provides a method for
a local utility company to limit the maximum
power level usage of the outdoor unit.

XP25

Crankcase Heater, Checkout and Status / Error Codes

OPERATION:

CRANKCASE HEATER (HR1)

Compressors in all units are equipped with a 40 or 70 watt (depending on unit size) belly-band type crankcase heater. The
heater prevents liquid from accumulating in the compressor. The heater is controlled by the crankcase heater thermostat.

CRANKCASE HEATER THERMOSTAT (S40)

Crankcase heater thermostat S40 controls the crankcase heater in all units and is located on the liquid line (see figure 2 on
page 6 for location).

1. When liquid line temperature drops below 50°F, the thermostat closes which results in the heater being energized.

2. When liquid line temperature rises above 70°F, the thermostat opens which results in the heater being de-energized.

Belly-Band Crankcase Heater - 240VAC, Watts

40 or 70

Crankcase Heater Thermostat

Figure 41. Belly-Band Crankcase Heater Thermostat

CHECKOUT:

Belly-Band Crankcase Heater: Using meter set on ohms, check crankcase heater resistance. If resistance is 0 ohms or

infinite, replace the crankcase heater.

Figure 42. Checking Belly-Band Crankcase Heater

Page 64

XP25

Crankcase Heater Thermostat: As the detected temperature changes the resistance across the sensor changes. Table 18
on page 78 shows how the resistance varies as the temperature changes for this sensor.

NOTE - When checking the ohms across a sensor, be aware that a sensor showing a resistance value that is not
range shown in table 18 on page 78, may be performing as designed. However, if a shorted or open circuit is detected, the
sensor is faulty; the sensor needs to be replaced.

Figure 43. Checking Crankcase Heater Thermostat

STATUS CODE:

None

ERROR CODES:

None

within the

Compressor Sound Cover

All units come with a soft-sided polyethylene molded outer shell compressor sound cover. The cover helps reduce any
unwanted operating sounds from the compressor. The cover features a hook/loop closure system for ease of installation on
the compressor.

Figure 44. Compressor Sound Cover

Page 65

XP25

Charge Compensator (XP25-024-230-XX and XP25-048-230-XX only)

The XP25024 and XP25048 units come with a factory-installed refrigerant charge compensator. The compensator helps
manage the refrigerant charge in the heating and cooling modes.

COOLING MODE

VAPOR LINE - TO
OUTDOOR COIL

COMPENSATOR TANK ­DURING COOLING
MODE, THE VAPOR LINE
IS HOTTER THAN THE
LIQUID LINE. STORED
LIQUID IS HEATED
(BOILED) AND FORCE
BACK INTO
CIRCULATION.

STORED LIQUID TO
LIQUID LINE TO BE
CIRCULATED THROUGH
INDOOR COIL.

(FROM COMPRESSOR

VAPOR LINE

DISCHARGE PORT)

Figure 45. Charge Compensator

Discharge Muffler (Heat Pumps only)

HEATING MODE

VAPOR LINE (TO

COMPRESSOR SUCTION

PORT)

VAPOR LINE - TO
OUTDOOR COIL

COMPENSATOR TANK - DURING
HEATING MODE, THE VAPOR LINE IS
COOLER THAN THE LIQUID LINE.
EXCESS REFRIGERANT IS FORCED
INTO THE CHARGE COMPENSATOR
WHERE IT CONDENSES AND
COLLECTS.

EXCESS REFRIGERANT
TO BE CONDENSED AND
STORED AS LIQUID.

The discharge muffler absorbs unwanted harmonic resonance from the compressor.

Figure 46. Top Discharge Muffler

XP25

Page 66

Liquid Line Bi-Flow Filter Drier (Heat Pumps only)

Filter-driers come in a variety of sizes, connection types, and materials of construction, but they essentially perform the same
function. All filter-driers contain the same functional parts. They contain desiccants to remove the water and acids, and they
contain a filtration system to remove the solid contaminants.

CHECKOUT:

If the filter drier becomes filled with debris, contaminants, or non-condensables, it restricts refrigerant flow. If the filter drier is
restricted, the outlet side of the filter drier is cooler than the inlet side. Some filter driers have an access port which allows you
to measure the pressure drop with a pressure gauge. If it is restrictive (Greater than 3 psig pressure difference), remove it from
the system and replace it.

Perform a moisture test on the system. If the test indicates moisture levels above what the moisture kit recommends, replace
the drier.

Note - Recommended practice is to replace the filter drier every time you open the system.

STATUS CODES:

None

ERROR CODES:

None

NOTE - If the drier is not operating correctly, the system is shut down by other controls, such as the high and low pressure
switches, which will generate a code.

Figure 47. Top Bi-Flow Filter Drier

Page 67

XP25

Check Expansion Valve (Heat Pumps only)

The thermostatic expansion valve (TEV) controls the flow of liquid refrigerant by maintaining superheat of the refrigerant
vapor at the outlet of the outdoor coil during heating mode.

CHECKOUT:

Table 14. Expansion Valve Checks

Problem

Superheat is too low ­valve feeds too much

Superheat is to high ­Valve does not feed or
does not feed enough

No superheat at start­up only - valve feeds
too much at start-up

Superheat is erratic or
hunts - system hunts or
cycles

Symptoms

1. Liquid slugging

2. Low superheat

3. Suction pressure normal or
high

1. Evaporator temperature too
high

2. High superheat

3. Low suction pressure

1. Liquid slugging

2. Zero super heat

3. Suction pressure higher
than normal

1. Suction pressure hunts

2. Superheat hunts

3. Erratic valve feeding

Causes Corrective Action

1. Replace with correct size valve

2. Adjust the superheat to correct set

1. Oversized valve

2. Incorrect superheat setting

3. Moisture

4. Dirt or foreign material

5. Incorrect charge selection

6. Incorrect bulb location

7. Incorrect equalizer location

8. Plugged equalizer (balanced
ported valve)

1. Low on refrigerant

2. High superheat

3. Flash gas in liquid line

4. Low or lost bulb charge

5. Moisture

6. Plugged equalizer (conventional
valve)

7. Insufficient pressure drop or
valve to small

8. Dirt or foreign material

9. Incorrect charge selection

10. Incorrect bulb location

11. Incorrect equalizer location

12. Charge migration

13. wax

14. Wrong equalizer type valve

15. Rod leakage (balanced port
valve)

16. Heat damaged power head

1. Refrigerant drainage

2. Compressor or suction line in a
cold location

3. Partially restricted or plugged
external equalizer (balance port
valve)

4. Liquid line solenoid will not com
pletely shut

1. Bulb location Incorrect

2. Too large a valve

3. Incorrect superheat setting

4. System design

ting

3. Replace the filter / driers

4. Evacuate the system and replace the
refrigerant

5. Clean out the material or replace the
valve

6. Select proper charge based on refri
gerant type

7. Relocate the bulb to proper location

8. Relocate the equalizer to proper loc
ation

9. Remove any restriction in the equal
izer tube

1. Add correct amount refrigerant

2. Change superheat setting

3. Remove source of restriction

4. Replace power element or valve

5. Replace driers or evacuate the sys
tem and replace refrigerant

6. Remove any restriction in the equal
izer tube

7. Replace existing valve with properly
sized valve

8. Clean out the material or replace the
valve

9. Select the correct charge

10. Move the bulb to the correct location

11. Move equalizer to correct location

12. Move valve to a warmer location or
apply heat tape to the power head

13. Use charcoal drier

14. Use externally equalized valve

15. Replace power head or valve

1. Use Pump Down Control

2. Install a trap at the top of the Evapor
ator

3. Install Crankcase Heater

4. Install Suction Solenoid

5. Remove restriction

6. Disassemble/Clean Valve

7. Replace valve

1. Reposition bulb

2. Replace existing valve with correct
sized valve

3. Adjust superheat to correct setting

4. Redesign system

Page 68

XP25

Table 14 Continued

Problem

Superheat appears nor
mal - system performs
poorly - valve does not
feed properly

Superheat is too low ­TEV feeds to much ­valve feeds too much

STATUS CODES:

None

Symptoms

1. Poor system performance

2. Low or normal superheat

3. Low suction pressure

1. Liquid slugging

2. Low superheat

3. Suction pressure normal or
high

Causes Corrective Action

1. Make necessary modification to bal
ance the load

1. Unequal circuit loading

2. Flow from one coil effecting an
other coil

3. Low load

4. Mismatched coil / compressor

5. Incorrect distributor

6. Evaporator oillogged

1. Oversized valve

2. Incorrect superheat setting

3. Moisture

4. Dirt or foreign material

5. Incorrect charge selection

6. Incorrect bulb location

7. Incorrect equalizer location

8. Plugged equalizer (balance port
valve)

2. Correct piping

3. Correct conditions causing the condi
tion

4. Correct match

5. Hot gas bypass

6. Add unloaded to compressor (if pos
sible)

7. Install correct distributor

8. Increase gas velocity through the coil

1. Replace with correct size valve

2. Adjust the superheat to correct set
ting

3. Replace the filter / driers

4. Evacuate the system and replace the
refrigerant

5. Clean out the material or replace the
valve

6. Select proper charge based on refri
gerant type

7. Relocate the bulb to proper location

8. Relocate the equalizer to proper loc
ation

9. Remove any restriction in the equal
izer tube

ERROR CODES:

None

NOTE - If the drier is not operating correctly, the system is shut down by other controls, such as the high and low pressure
switches, which will generate a code.

CHECK EXPANSION
VALVE - (HFC-410A)

CHECK EXPANSION
VALVE - (HFC-410A)
MICRO:06L
MICRO:06L

Figure 48. Plumbing (Component Locations and Specifications)

Page 69

XP25

Top Cap Switch Operation, Checkout and Status / Error Codes

OPERATION:

Some units are equipped with a compressor-mounted normally closed temperature switch that prevents compressor damage
due to overheating caused by internal friction. The switch is located on top of the compressor casing. This switch senses the
compressor casing temperature and opens at 239-257°F to shut off compressor operation. The auto-reset switch closes
when the compressor casing temperature falls to 151-187°F, and the compressor is re-energized. This single-pole,
single-throw (SPST) bi-metallic switch.

COMPRESSOR TOP CAP SWITCH

(SPST BI-METALLIC SWITCH,

NORMALLY OPENS AT 239-257ºF,

AND CLOSES AT 151-187ºF

SWITCH COVER

TOP OF COMPRESS0R

Figure 49. Top Cap Thermal Sensor Switch Operation

CHECKOUT:

Using a multimeter set to ohms, with the terminals disconnected from the system, check the resistance between the two
terminals of the top cap switch. If the resistance reading is 0 ohms, the switch is closed.

Figure 50. Top Cap Thermal Sensor Switch Checkout (S173)

STATUS:

None

ERROR:

Table 15. Outdoor Control 7-Segment Display Alert Codes - Top Cap Switch

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).
Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

Alert

Codes

E 422

E 442 Critical

Priority Alarm Description Possible Causes and Clearing Alarm

Moderate

Compressor top cap switch ex
ceeding thermal limit.

The top cap switch has opened 5
times within one hour. As a result,
the outdoor unit is locked out

®

thermostat.

Check condenser fan motor, TEV, indoor unit blower motor, stuck reversing valve,
clogged refrigerant filter or undercharge. When error occurs with inverter slowdown
errors, check for system overcharge. Automatically clears when error is corrected.

When compressor thermal protection sensor opens 5 times within 1 hour, outdoor stops

.

working. To clear, disconnect power to outdoor unit and restart.

XP25

Page 70

Reactor Operations, Checkout and Status / Error Codes

OPERATION:

Reactor (Inductor or choke) is a passive twoterminal electrical component that stores energy in its magnetic field.
Reactors are one of the basic components used in electronics where current and voltage change with time, due to the
ability of inductors to delay and reshape alternating currents.

CHECKOUT:
Main Power ON – Voltage IN reactor should be the same as the voltage OUT. With main power OFF and reactor

disconnected from system; resistance between leads should be the same (brown IN to brown OUT, blue IN to blue OUT).

Voltage “IN” same as Voltage “OUT”

Figure 51. XC/XP 25-024 and -036 Reactor

208/240
Voltage “IN”

208/240
Voltage
“OUT”

Figure 52. XC/XP 25-048 and -060 Reactor

STATUS CODES:

None

ERROR CODES:

None

Line Filter (Electromagnetic Compatibility Circuit - EMC) Operations, Checkout and Status /
Error Codes

OPERATION:

The line filter is being used to reduce the unintentional conducted emission from the equipment to a level sufficiently to
minimize electrical interference.

The filter is rated at 208/230 volt, 30 amp maximum, 60 Hertz.

NOTE - The 2- and 3-ton inverters have the EMC builtin. The 4- and 5-ton units have an external device (see illustration
below).

NOTE - A line filter is an electronic filter which is placed between electronic equipment and an external power source in

order to attenuate conducted radio frequency interference (RFI). RFI is also known as electromagnetic interference (EMI).

XP25

Page 71

L1

208/240
Voltage “IN”

L2

208/240
Voltage “OUT”

N1

N2

Figure 53. XP25 4- and 5-ton filter board (EMC)
CHECKOUT:
Voltage IN should read the same value as the Voltage OUT. With filter isolated from system, resistance between L1 and

L2 should be the same as resistance between N1 and N2.

STATUS CODES:

None

ERROR CODES:

None

Outdoor Fan Operation and Checkout

OPERATION:

These units use an integrated control and motor that is

programmed for variable-capacity operation. The fan speed is
controlled by the iComfort Wi-Fi

®

thermostat.

XP25 Fan Assembly

CHECKOUT:

VAC Voltage Check

Check for 208/240 VAC power at inverter contactor (red wires) (see figure 54).

With unit operating, check for main VAC to motor and outdoor control VDC output to motor:

1. No voltage present – Check main power

2. Voltage present – Perform DC volt checks (19 -23 VDC between FAN PWM and COM) (see figure 54)

Page 72

.

XP25

Perform DC volt checks (19 -23
VDC between FAN PWM and
COM).

Figure 54. VAC Voltage Check

Page 73

XP25

VDC Voltage Check: Check for VDC out of Fan PWM and COM. VDC output reading is determined by the percentage of
room thermostat demand (see figure 55).

1. No voltage present – Remove wires from control and check for VDC. If there is no voltage present then replace outdoor
control.

2. Voltage present – Perform a 9-volt battery test (see below) on motor.

STATUS CODES:

None

ERROR CODES:

None

BLACK LEAD

CONNECT B4 FAN MOTOR BLACK

COMMON WIRE TO 9V BATTERY

NEGATIVE TERMINAL

NEGATIVE TERMINAL

FULLY CHARGED 9V BATTERY

Figure 55. VDC Voltage Check

BROWN LEAD

CONNECT B4 FAN MOTOR WIRE
TO 9V BATTERY POSITIVE

V

TERMINAL

POSITIVE TERMINAL

NOTE - If the outdoor fan does not operate at the correct RPM, or does not start, the system is be down by other protection
components such as the high and low pressure switches which generate error code(s).

Ferrites

Electronic cabling and wires, by virtue of their lengthtowidth ratios, are perfect natural antennas. In the presence of
highspeed microprocessor signals, cables will conduct, radiate, and receive unwanted highfrequency signals. Use an
insertion-loss device, such as a ferrite suppressor as shown below, to control radio-frequency (RF) interference.

Ferrites are consistently stable over time and
over wide temperature ranges, and provide
RF suppression without causing large current
losses.

Figure 56. Ferrites

Page 74

XP25

Outdoor Control Operation, Checkout and Status / Error Codes

OPERATION:

The outdoor control is a microprocessor-based device for use with variable-capacity compressors up to 5-tons in capacity
operating on 24VAC residential power. The outdoor control integrates the functionality of maintaining compressor speed,
demand, defrost and fan PWM controls. The outdoor control is self-configuring. During start-up the outdoor control selects
one of two configurations  variable-capacity air conditioner or variable-capacity heat pump.

COMMUNICATION PLUG BETWEEN OUTDOOR

CONTROL AND INVERTER CONTROL

AMBIENT, COIL AND LIQUID

LINE SENSOR PLUG

NOTE - THE GREEN LED ON THE OUTDOOR CONTROL FLASHES
WHEN COMMUNICATION OCCURS BETWEEN THE OUTDOOR
CONTROL AND EITHER THE THERMOSTAT OR THE INVERTER.

PUSH

BUTTON

PUMP DOWN - WHEN UNIT IS IN PUMP DOWN MODE,  WILL BE

TO ACTIVATE PUMP DOWN MODE, REFER TO PUMP DOWN

DISPLAYED ON 7-SEGMENT.

CYCLE SEQUENCE ON PAGE 39.

7-SEGMENT

DISPLAY

Figure 57. Outdoor Control Operation

STATUS CODES:

Table 16. Outdoor Control 7-Segment Display Alert Codes - Outdoor Control Status

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).
Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

Alert

Codes

E 600 Critical

E 601 Critical

Priority Alarm Description Possible Causes and Clearing Alarm

Compressor has been cycled OFF
on utility load shedding.

Outdoor unit has been cycled OFF
on low temperature protection.

®

thermostat.

Load shedding function: Provides a method for a local utility company to limit the maxim
um power level usage of the outdoor unit.

Low temperature protection: Outdoor unit will not operate when the outdoor temperat
ure is at or below 4°F (20°C). If the unit is operating and the outdoor temperature
drops below 4°F (20°C), the unit continues to operate until the room thermostat is sat
isfied or the outdoor temperature drops to 15°F (26°C). Outdoor unit ambient sensor
provides temperature readings.

Page 75

XP25

ERROR CODES:

Table 17. Outdoor Control 7-Segment Display Alert Codes - Outdoor Control Errors

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).
Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

®

thermostat.

Alert

Codes

E 105 Moderate

E 120 Moderate

E 124 Critical

E 125 Critical

E 131 Critical

E 132 Critical Internal software error. Replace outdoor control.

Priority Alarm Description Possible Causes and Clearing Alarm

Equipment is unable to communicate. Indicates numerous message errors. In most
The outdoor control has lost com
munication with either the thermo
stat or indoor unit.

There is a delay in the outdoor unit
responding to the system.

The iComfort WiFi® thermostat has
lost communication with the out
door unit for more than 3 minutes.

There is a hardware problem with
the outdoor control.

The outdoor unit control parameters
are corrupted

cases errors are related to electrical noise. Make sure high voltage power is separ

ated from RSBus. Check for miswired and/or loose connections between the stat,

indoor unit and outdoor unit. Check for a high voltage source of noise close to the

system. Fault clears after communication is restored.

Typically, this alarm/code does not cause any issues and will clear on its own. The

alarm / code is usually caused by a delay in the outdoor unit responding to the ther

mostat. Check all wiring connections. Cleared after unresponsive device responds to

any inquiry

Equipment lost communication with the thermostat. Check the wiring connections,

ohm wires and cycle power. The alarm stops all associated HVAC operations and

waits for a heartbeat message from the unit that's not communicating. The alarm /

fault clears after communication is reestablished.

There is a control hardware problem. Replace the outdoor control if the problem pre

vents operation and is persistent. The alarm / fault is cleared 300 seconds after the

fault recovers.

Reconfigure the system. Replace the control if heating or cooling is not available

Unit Sensor Operations, Checkout and Status / Error Codes

OPERATION

Coil Temperature Sensor (RT21)

Coil temperatures, as read by the sensor (shown in figure 59), which are below -35°F (-37°C) or above 120°F (48°C) trigger a
fault condition. If the defrost coil sensor is open, shorted, or out of the temperature range, the outdoor control will not perform
defrost operation (demand or time/temperature) and displays the appropriate fault code (see table 19 on page 79). Heating
and cooling operation is allowed during this fault condition.

Ambient Temperature Sensor (RT13)

Ambient temperatures, as read by the ambient temperature sensor (shown in figure 59), which are below -35°F (-37°C) or
above 120°F (48°C) trigger a fault condition. If the ambient sensor is open, shorted, or out of the temperature range of the
sensor, the control does not perform demand defrost operation. The control reverts to time/temperature defrost operation and
displays the appropriate alert code (see table 19 on page 79). Heating and cooling operation is allowed in this fault condition.

Liquid Line Temperature Sensor (RT36)

Liquid line temperatures below -40°F (-40°C) or above 140°F (60°C) trigger a fault condition and result in the appropriate
alarm code (see table 19 on page 79). The outdoor control uses the liquid line sensor to change the fan speed, allowing cooling
operation at lowered ambient temperatures.

Page 76

XP25

COIL

SENSOR

COIL

OUTDOOR

AMBIENT

LIQUID LINE

TEMP RANGE ºF

(ºC)

-40 (-40) TO
140 (60)

RESISTANCE VALUES

RANGE (OHMS)

336,000 to 2,487 (see
table 18 on page 78 for
exact temperature to
ohm readings)

PIN# / WIRE

SLEEVE COLOR

6 AND 5

(BROWN)

4 AND 3

(BLACK)

2 AND 1

(YELLOW)

OUTDOOR

AMBIENT

LIQUID LINE

BLACK WIRES WITH

BROWN SLEEVE

BLACK WIRES WITH

BLACK SLEEVE

BLACK WIRES WITH

YELLOW SLEEVE

TEMPERATURE

SENSOR HARNESS

Figure 58. Temperature Sensor Specifications

CHECKOUT

Sensors connect to the outdoor control through a field‐replaceable harness assembly that plugs into the control. Through the
sensors, the control detects outdoor ambient, coil and liquid temperature fault conditions. As the detected temperature
changes, the resistance across the sensor changes. Table 18 on page 78 shows how the resistance varies as the temperature
changes for both type of sensors. Check sensor operation by reading ohms across pins shown in figure 58.

NOTE - When checking the ohms across a sensor, be aware that a sensor showing a resistance value that is not within the
range shown in table 18 on page 78, may be performing as designed. However, if a shorted or open circuit is detected, then the
sensor may be faulty and the sensor harness will need to be replaced.

(-048) COIL TEMPERATURE
SENSOR (RT21) - ON

(-024 AND -036) COIL
TEMPERATURE SENSOR
(RT21) - ON RETURN BEND,
12 TUBES UP FROM
BOTTOM (11.50' UP)

RETURN BEND, 16 TUBES
UP FROM BOTTOM (15.50'
UP)

(-060) COIL TEMPERATURE
SENSOR (RT21) - ON
RETURN BEND, 12 TUBES
UP FROM BOTTOM (11.50'
UP)

CRANKCASE HEATER

THERMOSTAT (S40) OPENS AT

70ºF, CLOSES AT 50ºF

OUTDOOR AMBIENT

TEMPERATURE

SENSOR

Figure 59. Temperature Sensor Locations

LIQUID LINE SENSOR

XP25

Page 77

Degrees Fahr
enheit

136.3 2680 56.8 16657 21.6 44154 -11.3 123152

133.1 2859 56.0 16973 21.0 44851 -11.9 125787

130.1 3040 55.3 17293 20.5 45560 -12.6 128508

127.3 3223 54.6 17616 20.0 46281 -13.2 131320

124.7 3407 53.9 17942 19.4 47014 -13.9 134227

122.1 3592 53.2 18273 18.9 47759 -14.5 137234

119.7 3779 52.5 18607 18.4 48517 -15.2 140347

117.5 3968 51.9 18945 17.8 49289 -15.9 143571

115.3 4159 51.2 19287 17.3 50074 -16.5 146913

113.2 4351 50.5 19633 16.8 50873 -17.2 150378

111.2 4544 49.9 19982 16.3 51686 -17.9 153974

109.3 4740 49.2 20336 15.7 52514 -18.6 157708

107.4 4937 48.5 20695 15.2 53356 -19.3 161588

105.6 5136 47.9 21057 14.7 54215 -20.1 165624

103.9 5336 47.3 21424 14.1 55089 -20.8 169824

102.3 5539 46.6 21795 13.6 55979 -21.5 174200

100.6 5743 46.0 22171 13.1 56887 -22.3 178762

99.1 5949 45.4 22551 12.5 57811 -23.0 183522

97.6 6157 44.7 22936 12.0 58754 -23.8 188493

96.1 6367 44.1 23326 11.5 59715 -24.6 193691

94.7 6578 43.5 23720 11.0 60694 -25.4 199130

93.3 6792 42.9 24120 10.4 61693 -26.2 204829

92.0 7007 42.3 24525 9.9 62712 -27.0 210805

90.6 7225 41.7 24934 9.3 63752 -27.8 217080

89.4 7444 41.1 25349 8.8 64812 -28.7 223677

88.1 7666 40.5 25769 8.3 65895 -29.5 230621

86.9 7890 39.9 26195 7.7 67000 -30.4 237941

85.7 8115 39.3 26626 7.2 68128 -31.3 245667

84.5 8343 38.7 27063 6.7 69281 -32.2 253834

83.4 8573 38.1 27505 6.1 70458 -33.2 262482

82.3 8806 37.5 27954 5.6 71661 -34.1 271655

81.2 9040 37.0 28408 5.0 72890 -35.1 281400

80.1 9277 36.4 28868 4.5 74147 -36.1 291774

79.0 9516 35.8 29335 3.9 75431 -37.1 302840

78.0 9757 35.2 29808 3.4 76745 -38.2 314669

77.0 10001 34.7 30288 2.8 78090 -39.2 327343

76.0 10247 34.1 30774 2.3 79465

75.0 10496 33.5 31267 1.7 80873

74.1 10747 33.0 31766 1.2 82314

73.1 11000 32.4 32273 0.6 83790

72.2 11256 31.9 32787 0.0 85302

71.3 11515 31.3 33309 -0.5 86852

70.4 11776 30.7 33837 -1.1 88440

69.5 12040 30.2 34374 -1.7 90068

68.6 12306 29.6 34918 -2.2 91738

67.7 12575 29.1 35471 -2.8 93452

66.9 12847 28.6 36031 -3.4 95211

66.0 13122 28.0 36600 -4.0 97016

65.2 13400 27.5 37177 -4.6 98870

64.4 13681 26.9 37764 -5.2 100775

63.6 13964 26.4 38359 -5.7 102733

62.8 14251 25.8 38963 -6.3 104746

62.0 14540 25.3 39577 -6.9 106817

61.2 14833 24.8 40200 -7.5 108948

60.5 15129 24.2 40833 -8.2 1111 41

59.7 15428 23.7 41476 -8.8 113400

59.0 15730 23.2 42130 -9.4 115727

58.2 16036 22.6 42794 -10.0 118126

57.5 16345 22.1 43468 -10.6 120600

Resistance

Degrees Fahr
enheit

Resistance

Degrees Fahr
enheit

Resistance

Degrees Fahr
enheit

Resistance

Table 18. Ambient, Coil and Liquid Line Sensors Temperature / Resistance Range

Page 78

XP25

ERROR CODES:

Table 19. Outdoor Control 7-Segment Display Alert Codes - Outdoor Control Errors

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).
Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

®

thermostat.

Alert

Codes

E 180 Critical

E 416

E 424 Moderate

Priority Alarm Description Possible Causes and Clearing Alarm

In normal operation, after outdoor control recognizes sensors, the alarm is sent if
valid temperature reading is lost. Compare outdoor sensor resistance to temperat
ure/resistance charts in unit installation instructions. Replace sensor pack if neces
sary. At the beginning of (any) configuration, furnace or airhandler control detects
the presence of the sensor(s). If detected (reading in range), appropriate feature is
shown in the iComfort WiFi
configuration, or when normal values are sensed.

Coil sensor being detected open or shorted, or temperature is out of coil sensor
range. Outdoor unit control will not perform demand or time/temperature defrost
operation. System is still able heat and cool. Check the resistance of the coil sensor
and compare to temperature resistance chart. Replace coil sensor if needed. The
alarm clears when outdoor unit control detects proper coil sensor readings or after a
power reset.

In normal operation, after outdoor control recognizes sensors, the alarm is sent if
valid temperature reading is lost. Compare liquid line sensor resistance to temperat
ure/resistance charts in unit installation instructions. Replace sensor pack if neces
sary. At the beginning of (any) configuration, furnace or airhandler control detects
the presence of the sensor(s). If detected (reading in range), appropriate feature is
shown in the iComfort WiFi
configuration, or when normal values are sensed.

®

thermostat About screen. The alarm / fault clears upon

®

thermostat About screen. The alarm / fault clears upon

Moderate/

Critical

The outdoor unit ambient temper
ature sensor has malfunctioned.
As a result the outdoor unit control
will not perform low ambient cool
ing.

The outdoor coil sensor has mal
functioned. As a result the out
door unit control will not perform
defrost.

The liquid line temperature sensor
has malfunctioned.

Variable-capacity Inverter Control Operation, Checkout, Status / Error Codes

OPERATION OF COMPONENTS:

Electromagnetic compatibility circuit (EMC): EMC ensures the correct operation of different equipment items which use or
respond to electromagnetic phenomena, and the avoidance of any interference effects.

NOTE - The 2- and 3-ton DC inverter control has the EMC builtin. The 4- and 5-ton units have an external EMC.

CONVERTER:

Converts AC (alternating current) to DC (direct current).

POWER FACTOR CORRECTION (PFC) CIRCUIT:

The PFC module is an integrated part of the outdoor DC inverter control that monitors the DC bus for high, low and abnormal
voltage conditions. If any of these conditions are detected, the PFC function and compressor will stop.

INTELLIGENT (INVERTER) POWER MODULE (IPM):

The IPM inverts DC voltage into AC voltage. The control method is known as pulse width modulation (PWM). This means the
DC is switched on and off very quickly (chopped) by the transistor switches to make simulated AC at required frequency and
voltage.

COMMUNICATION CONTROL CIRCUIT:

Receives and sends message between the DC inverter control and the outdoor control.

Power Factor Correction Circuit

Converter

Intelligent Power Module

Electromagnetic Compatibility Circuits

Communication Control

Figure 60. 2- and 3-Ton Unit Inverter

XP25

Page 79

Heat Sink

Converter

Power Factor
Correction
Circuit

Intelligent Power Module

Communication Control

Figure 61. 4- and 5-Ton Unit Inverter

STATUS CODES:

Table 20. Outdoor Control 7-Segment Display Alert Codes, DC Inverter and Outdoor Control LED Flash Codes

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).
Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

Alert

Codes

N/A N/A ON OFF N/A XC/XP 25-024 and -036 only: Indicates inverter is operating normally.

N/A N/A ON ON N/A XC/XP 25-048 and -060 only: Indicates inverter is operating normally.

N/A N/A OFF OFF N/A Indicates inverter is NOT energized.

Code

Inverter LED Flash Code
(number of flashes)

Red LED Green LED

®

thermostat.

Priority Possible Causes and Clearing Alarm

ERROR CODES:

Table 21. Outdoor Control 7-Segment Display Alert Codes and Inverter LED Flash Codes

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).
Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

Alert

Codes

E 423 40 4 flashes OFF

E 426 N/A N/A N/A Critical

E 427 21 2 flashes 1 flash

Code

Inverter LED Flash Code
(number of flashes)

Red LED Green LED

®

thermostat.

Priority Alarm Description Possible Causes and Clearing Alarm

Moderate /

Critical

Moderate /
Critical

The inverter has detec

ted a circuit problem

Excessive inverter

alarms

The inverter has detected a DC peak fault condition. If condition (55A or high
er) is detected, outdoor unit compressor and fan stop. Anti-short cycle is initi
ated. If peak current (55A or higher) occurs 10 times within an hour, system is
locked out. Indicates high pressure, condenser fan failure, locked compressor
rotor or overcharge. To clear, disconnect power to outdoor unit and restart.

Control locks out after 10 strikes within an hour. To
clear, disconnect power to outdoor unit and re

.

start.

After ten faults within one hour, control is locked
out, indicating poor system operation. Review his
tory of alarms to resolve system setup. Check con
denser fan motor, TXV, indoor unit blower motor,
over-charge, undercharge, or clogged refrigerant
filter.

To clear error, disconnect power to outdoor unit
and restart. Inverter alarms 12 to 14 and 53 do not
count towards this lock out condition.

Table 21. Outdoor Control 7-Segment Display Alert Codes and Inverter LED Flash Codes

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).
Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

®

thermostat.

XP25

Page 80

Alert

Codes

E 428 22 2 flashes 2 flashes

E 429 23 2 flashes 3 flashes

E 431 27 2 flashes 7 flashes

E 432 28 2 flashes 8 flashes

E 433 29 2 flashes 9 flashes

Code

Inverter LED Flash Code
(number of flashes)

Red LED Green LED

Priority Alarm Description Possible Causes and Clearing Alarm

If condition is detected, is detected, outdoor unit
compressor and fan stop. Antishort cycle is initi
ated. If condition occurs 5 times within an hour,

Moderate /
Critical

Moderate /
Critical

Moderate /
Critical

Moderate /
Critical

Moderate /
Critical

The inverter has detec
ted a high main input cur
rent condition

On a call for compressor
operation, if DC link
power in inverter does
not rise above 180 VDC
for 2 and 3 ton models,
250 VDC for 4 and 5 ton
models, within 30
seconds, the control will
display a moderate code.
If condition is detected,
outdoor unit will stop
(Compressor and fan).
Anti-short cycles is initi
ated. If condition occurs
10 times within a 60
minute rolling time period,
system will lock out and
display a critical code.

Error occurs when PFC
detects an over-current
condition of 100A, the
control will display a
moderate code. If condi
tion is detected, outdoor
unit will stop (Com
pressor and fan). Anti­short cycle is initiated. In
verter is unavailable to
communicate with the
outdoor control for 3
minutes. If condition oc
curs 10 times within a 60
minute rolling time period,
system will lock out and
display a critical code.

The inverter has detec
ted a DC link high voltage
condition.

The inverter has detected
a compressor over-cur
rent condition

.

.

system is locked out.

Indicates high pressure, condenser fan failure or
overcharge.

To clear, disconnect power to outdoor unit and re
start.

Issues:

(1) If DC link power in inverter does not rise
above 180 VDC for 2- and 3-ton models, 250
VDC for 4- and 5-ton models, within 30 seconds,
the outdoor control will display a moderate code.

(2) Capacitors on inverter do not properly charge.

Corrective Actions:

(1) check for proper main power to outdoor unit
and for any loose electrical connections.

(2) Outdoor control boards with part # 103686-03
have software update to delay the de-energizing
of the reversing valve by four seconds when com
ing out of defrost.

Issues:

(1) Indicates power interruption, brownout, poor
electrical connection or loose inverter input wire.

(2) System testing was set up and code was gen
erated when the reversing valve is de-energized
coming out of defrost (code appears with or
without 30 compressor delay).

Corrective Actions:

(1) Check for proper main power to outdoor unit
and for any loose electrical connections.

(2) Outdoor control boards with part # 103686-03
have software update to delay the de-energizing
of the reversing valve by four seconds when com
ing out of defrost.

Error occurs when the DC link capacitor voltage is
greater than 480VDC. If condition is detected, out
door unit compressor and fan stop. Antishort
cycle is initiated. If condition occurs 10 times within
an hour, system is locked out. System stops. To
clear, disconnect power to outdoor unit and re
start.

Error occurs when compressor peak phase cur
rent is greater than 28A. Inverter issues code 14
first and slows down to try to reduce the current. If
the current remains high, outdoor unit compressor
and fan stop. Antishort cycle is initiated. If condi
tion occurs 5 times within an hour, system is
locked out. To clear disconnect power to outdoor
unit and restart.

Page 81

XP25

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).

Table 21. Outdoor Control 7-Segment Display Alert Codes and Inverter LED Flash Codes

Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

®

thermostat.

Alert

Codes

Code

Inverter LED Flash Code
(number of flashes)

Red LED Green LED

E 434 53 5 flashes 3 flashes

E 435 60 6 flashes OFF

E 436 62 6 flashes 2 flashes

Priority Alarm Description Possible Causes and Clearing Alarm

Outdoor control has lost
communications with the

Moderate /
Critical

inverter for greater than
3 minutes. Outdoor con
trol will stop all com
pressor demands, re
cycle power to the invert
er by de-energizing the
contactor for 2 minutes.
If this occurs 3 time in
one thermostat call, the
outdoor unit will locked

Issues:

(1) Loose electrical connections.

(2) Interruption of main power to inverter.

Corrective Actions:

(1) Check all electrical connections.

(2) Check for proper main power to inverter.

out and display a critical
code.

When this error occurs, the outdoor control cycles

Moderate /
Critical

Inverter internal error.

power to the inverter by opening the contactor for
2 minutes. Check that the EEPROM is properly
seated. After power is cycled to the inverter 3
times, the outdoor unit is locked out

.

Inverter heat sink tem
perature exceeded limit.
Occurs when the heat
sink temperature ex

Moderate /
Critical

ceeds the inverter limit.
Inverter issues code 13
first, then slows down to
allow the heat sink to
cool. If temperature re
mains high, outdoor unit
stops (compressor and
fan). Anti-short cycle is
initiated. If condition oc
curs 5 times within an

Issue: Feedback from supplier tear down of inverter
indicates that the screws that hold the inverter to the
inverter board were loose causing poor contact
between these two components.

Corrective Action: Tighten screws that hold the
heat sink to the inverter control board.

NOTE: Wait five minutes to all capacitor to dis
charge before checking screws.

hour, system is locked
out. To clear, disconnect
power to outdoor unit
and restart.

E 437 65 6 flashes 5 flashes

E 438 73 7 flashes 3 flashes

Moderate /

Critical

Moderate /
Critical

Heat sink temperature
sensor fault has occurred
(temperature less than 4
ºF or greater than 264ºF
after 10 minutes of opera
tion)

.

The inverter has detec
ted a PFC over current
condition. This would be
caused by a high load
condition, high pressure,
or outdoor fan fail
ure.Outdoor control will
display the code when
the inverter has the er
ror. After 3 minutes, the
inverter will reset and
the compressor will turn
on again. If it happens
10 times within a 60
minute rolling time peri
od, the OD control will
lock out operation of the
outdoor unit and display
a critical code.

Page 82

This occurs when the temperature sensor detects
a temperature less than 0.4ºF or greater than
264ºF after 10 minutes of operation. If condition is
detected, outdoor unit compressor and fan stop.
Antishort cycle is initiated. If condition occurs 5
times within an hour, system is locked out. To clear
disconnect power to outdoor unit and restart. If
problem persists, replace inverter.

Issue: Possible issue is system running at high
pressures. Check for high pressure trips or other
alert codes in room thermostat and outdoor control.

XP25

NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).

Table 21. Outdoor Control 7-Segment Display Alert Codes and Inverter LED Flash Codes

Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi

Alert

Codes

E 439 12 1 flash 2 flashes Moderate

E 440 13 1 flash 3 flashes Moderate

E 441 14 1 flash 4 flashes Moderate

Code

Inverter LED Flash Code
(number of flashes)

Red LED Green LED

®

thermostat.

Priority Alarm Description Possible Causes and Clearing Alarm

Input current is approaching a high limit. Com

Compressor slowdown

due to high input cur

rent.

Heat sink temperature is
approaching limit. The
compressor speed auto
matically slows to re
duce heat sink temperat
ure. The control sets in
door CFM and outdoor
RPM to values accord
ing to demand percent
age rather than the actu
al Hz. Alarm is automat
ically cleared.

Compressor slowdown
due to high compressor
current. Compressor
current is approaching
limit. The compressor
speed automatically
slows. The control sets
indoor CFM and outdoor
RPM to values accord
ing to demand percent
age rather than the actu
al Hz. Alarm is automat
ically cleared..

pressor speed will automatically slow down. The
control continues sending the inverter speed de
manded by the thermostat. The control will set in
door CFM and outdoor RPM to values according
to demand percentage rather than the actual Hz.
Alarm is automatically clear. See E428.

Issue: Feedback from supplier tear down of invert
er indicates that the screws that hold the inverter to
the inverter board were loose causing poor contact
between these two components.

Corrective action: Tighten screws that hold the
heat sink to the inverter control board.

NOTE: Wait 5 minutes to all capacitor to discharge
before checking screws.

Issue: Possible issue is system running at high
pressures. Check for high pressure trips or other
alert codes in room thermostat and outdoor control.

Page 83

XP25

Emergency 24VAC System Operation

The Y and O terminals located on the outdoor control allow the outdoor unit to be cycled ON and OFF using 24VAC inputs. The
outdoor unit will operate at 100% capacity in this configuration.

NOTE - Defrost operation will not have any indoor discharge air tempering due to the lack of a W1 out terminal.

The following wiring diagrams display the wiring changes needed to switch a full communicating system to a partial
communicating system with the XP25 running in emergency mode (24VAC inputs to outdoor unit).

iComfort Wi-Fi® Thermostat

Communicating Air Handler and XP25

Communicating Air

Handler or

Furnance

iComfort Wi−Fi

THERMOSTAT



XP25 UNIT

RSBus

XC25 XP25

DO NOT CUT

NOTE 3

24VAC Thermostat

C

NOTE 1

R

O

Y

Emergency 24VAC

(Non-Communicating Mode)

Communicating Air

Handler or

Furnance

NOTE 2

CUT LINK

XP25 UNIT

NOTES:

1. Move two wires on both indoor and outdoor controls from terminals i+ to Y1 and i- to O for 24VAC operation on heat pump and indoor unit.

2. Do not disconnect wires from the XP25 R and C terminals, both are required.

3. Cut R to O link on indoor control.

Figure 62. Thermostat Communication Mode

Page 84

XP25

System Refrigerant

IMPORTANT !

The system must be operating at full capacity during
charging. Increase (heat) or decrease (cooling) the
thermostat setting by 5°F to create system demand.
Confirm outdoor unit running capacity on the display
on the outdoor control. Value should be 100%.

This section outlines procedures for:

1. Connecting gauge set for testing and charging as
illustrated in figure 63.

2. Checking and adjusting indoor airflow as described in
figure 64.

3. Adding or removing refrigerant using the weigh-in
method shown in figure 65, and verifying charge using
subcooling method described in figure 66.

GAUGE SET

CONNECTIONS FOR TESTING AND CHARGING

TRUE SUCTION PORT

B

CONNECTION

IMPORTANT - Unit must be operating at 100% input to
charge properly.

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.

COOLING MODE INDOOR AIRFLOW CHECK

Check airflow using the Delta-T (DT) process using the
illustration in figure 64.

The diagnostic screen on the thermostat or outdoor control
7-Segment display shows indoor and outdoor motor CFMs
or RPMs.

MANIFOLD GAUGE SET

LOW

HIGH

OUTDOOR UNIT

REFRIGERANT TANK

CHARGE IN

LIQUID PHASE

DIGITAL SCALE

INSIDE OUTDOOR UNIT

TEMPERATURE

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 TRUE SUCTION 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.

D

SENSOR

A

TO LIQUID

LINE SERVICE

VALV E

C

TEMPERATURE SENSOR

(LIQUID LINE)

Figure 63. Gauge Set Connections

Page 85

XP25

AIRFLOW

INDOOR COIL

TEMPERATURE OF AIR
ENTERING INDOOR COIL ºF

A

DRY

BULB

C

53º

ALL TEMPERATURES ARE
EXPRESSED IN ºF

ASSUME DT = 15 AND A TEMP. = 72º, BELOW C TEMPERATURES REQUIRE ACTION:

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

T

DROP

19º

AIR
FLOW

– DT = ºF ACTION

INDOOR
COIL

AIR
FLOW

B

64º

72º

DRY BULB

WET

BULB

DRY-BULB

WET-BULB ºF

A

USE THE FOLLOWING PROCEDURE TO ADJUST FOR OPTIMAL
AIR FLOW ACROSS THE INDOOR COIL:

1. DETERMINE THE DESIRED DT — MEASURE ENTERING AIR

2. FIND TEMPERATURE DROP ACROSS COIL

3. DETERMINE IF FAN NEEDS ADJUSTMENT — IF THE DIF

NOTE - CHANGING AIR FLOW AFFECTS ALL TEMPERA
TURES; RECHECK TEMPERATURES TO CONFIRM THAT THE
TEMPERATURE DROP AND DT ARE WITHIN +

4. ADJUST THE FAN SPEED — SEE INDOOR UNIT IN

DT

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
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

B

TEMPERATURE USING DRY BULB (A) AND WET BULB (B).

DT IS THE INTERSECTING VALUE OF A AND B IN THE
TABLE (SEE TRIANGLE).

— MEASURE

THE DRY BULB AIR TEMPERATURE ENTERING AND LEAV
ING THE COIL (A AND C). TEMPERATURE DROP FORMULA:

) = A MINUS C.

(T

DROP

FERENCE BETWEEN THE MEASURED T
SIRED DT (T
NEEDED. SEE EXAMPLE AT LEFT:

STRUCTIONS TO INCREASE/DECREASE FAN SPEED.

–DT) IS WITHIN +3º, NO ADJUSTMENT IS

DROP

AND THE DE

DROP

3º.

Figure 64. Checking Indoor Airflow over Evaporator Coil Using Delta-T Chart

Page 86

XP25

Use WEIGH-IN method for adding initial refrigerant charge, then use SUBCOOLING method for for verifying
refrigerant charge.

WEIGH-IN

CHARGING METHOD FOR LONG LINE SETS

64ºF (17.7ºC) and Below

Adjust amount for variation in

Amount specified

on nameplate

line set length and liquid line
diameter using table below.

+

Liquid Line

Set Diameter

5/16”

3/8”

1/2”

=

HFC-410A

(ounces per foot)

0.40

0.60

1.00

Total charge

Figure 65. Using HFC-410A Weigh In Method

(All charging MUST be performed while system is operating either at maximum speed or 100% demand.)

SUBCOOLING

CHARGING METHOD

USE

COOLING

MODE

60ºF

(15ºC)

USE

HEATING

MODE

SATº
LIQº –
SCº =

1. THE DIAGNOSTIC SCREEN ON THE THERMOSTAT OR OUTDOOR CONTROL 7-SEGMENT DISPLAY WILL SHOW
INDOOR AND OUTDOOR MOTOR CFMS OR RPMS.

2. MEASURE OUTDOOR AMBIENT TEMPERATURE; DETERMINE WHETHER TO USE COOLING MODE OR HEATING MODE
TO CHECK CHARGE.

3. CONNECT GAUGE SET.

4. CHECK LIQUID AND VAPOR LINE PRESSURES. COMPARE PRESSURES WITH EITHER HEAT OR COOLING MODE
NORMAL OPERATING PRESSURES IN THE APPLICABLE CHARGING STICKER, NORMAL OPERATING PRESSURES,
HIGH STAGE.

NOTE - THE REFERENCE TABLE IS A GENERAL GUIDE. EXPECT MINOR PRESSURE VARIATIONS. SIGNIFICANT
DIFFERENCES MAY MEAN IMPROPER CHARGE OR OTHER SYSTEM PROBLEM.

5. SET THERMOSTAT FOR HEAT/COOL DEMAND, DEPENDING ON MODE BEING USED:

USING COOLING MODE — WHEN THE OUTDOOR AMBIENT TEMPERATURE IS 60°F (15°C) AND ABOVE. TARGET

SUBCOOLING VALUES (SECOND STAGE - HIGH CAPACITY) IN APPLICABLE CHARGING STICKER ARE BASED ON 70
TO 80°F (21-27°C) INDOOR RETURN AIR TEMPERATURE; IF NECESSARY, OPERATE HEATING TO REACH THAT
TEMPERATURE RANGE; THEN SET THERMOSTAT TO COOLING MODE SETPOINT TO 68ºF (20ºC) WHICH SHOULD
CALL FOR SECOND-STAGE (HIGH STAGE) COOLING. WHEN PRESSURES HAVE STABILIZED, CONTINUE WITH STEP

6.

USING HEATING MODE — WHEN THE OUTDOOR AMBIENT TEMPERATURE IS BELOW 60°F (15°C). TARGET

SUBCOOLING VALUES (SECOND-STAGE - HIGH CAPACITY) IN APPLICABLE CHARGING STICKER ARE BASED ON
65-75°F (18-24°C) INDOOR RETURN AIR TEMPERATURE; IF NECESSARY, OPERATE COOLING TO REACH THAT
TEMPERATURE RANGE; THEN SET THERMOSTAT TO HEATING MODE SETPOINT TO 77ºF (25ºC) WHICH SHOULD
CALL FOR SECOND-STAGE (HIGH STAGE) HEATING. WHEN PRESSURES HAVE STABILIZED, CONTINUE WITH STEP

6.

6. READ THE LIQUID LINE TEMPERATURE; RECORD IN THE LIQº SPACE.

7. READ THE LIQUID LINE PRESSURE; THEN FIND ITS CORRESPONDING TEMPERATURE IN THE TEMPERATURE/
PRESSURE CHART LISTED IN THE APPLICABLE CHARGING STICKER AND RECORD IT IN THE SATº SPACE.

8. SUBTRACT LIQº TEMPERATURE FROM SATº TEMPERATURE TO DETERMINE SUBCOOLING; RECORD IT IN SCº
SPACE.

9. COMPARE SCº RESULTS WITH APPLICABLE CHARGING STICKER, BEING SURE TO NOTE ANY ADDITIONAL
CHARGE FOR LINE SET AND/OR MATCH-UP.

10. IF SUBCOOLING VALUE IS GREATER THAN SHOWN IN APPLICABLE CHARGING STICKER FOR THE APPLICABLE
UNIT, REMOVE REFRIGERANT; IF LESS THAN SHOWN, ADD REFRIGERANT.

11. IF REFRIGERANT IS ADDED OR REMOVED, REPEAT STEPS 6 THROUGH 10 TO VERIFY CHARGE.

12. DISCONNECT GAUGE SET AND RE-INSTALL BOTH THE LIQUID AND SUCTION SERVICE VALVE CAPS.

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.

NOTE - The above nameplate is shown for illustration purposes
only. Go to actual nameplate on outdoor unit for charge information.

Charging Formula for Liquid Line Charge Adjustments

[(Line set oz./ft. x total length)  (factory charge for line set)] = charge adjustment

Example: Units are factorycharged for 15 feet (4.6 meters) of 3/8" line set.
Factory charge for 3/8" is 0.60 oz/ft x 15 = 9.0 ounces.

Figure 66. Using HFC-410A Subcooling Method — High Speed (High Capacity)

Page 87

XP25

Table 22

. 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

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 85 254.1 100 317.2 116 396.0 131 481.6 147 586.8

39 115.8 55 155.5 70 200.6 86 258.0 101 321.8 117 401.3 132 487.8 148 593.8

40 118.0 56 158.2 71 203.9 87 262.0 102 326.4 118 406.7 133 494.0 149 601.0

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

125 445.9

141 545.6

Page 88

XP25

Figure 67. XP25 Charging Sticker

Page 89

XP25