Page 1
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2012 Lennox Industries Inc.
Corp. 1031−L7
Revised August 17, 2012
XP21
INSTALLATION AND SERVICE
PROCEDURE
Service Literature
Dave Lennox Signature
®
Collection XP21 Series Units
NOTICE
A thermostat is not included and must be ordered
separately.
The Lennox icomfort thermostat must be used in
communicating applications.
In non−communicating applications, the Lennox
ComfortSense
®
7000 thermostat may be used, as well
as other non−communicating thermostats.
In all cases, setup is critical to ensure proper system
operation.
Field wiring examples for non−communicating
applications begin on page 22.
See the icomfort thermostat Quick Start Guide for
communicating and partial communicating field wiring
connections.
WARNING
Improper installation, adjustment, alteration, service or
maintenance can cause personal injury, loss of life, or
damage to property.
Installation and service must be performed by a licensed
professional installer (or equivalent) or a service agency.
IMPORTANT
The Clean Air Act of 1990 bans the intentional venting of
refrigerant (CFCs, HCFCs AND HFCs) as of July 1, 1992.
Approved methods of recovery, recycling or reclaiming
must be followed. Fines and/or incarceration may be
levied for noncompliance.
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. . . . . . . . . . . . . . . . .
Operating Gauge Set 6. . . . . . . . . . . . . . . . . . . . . . . . . .
General 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
II. INSTALLATION
Unit Placement 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removing and Installing Panels 11. . . . . . . . . . . . . . . . .
New or Replacement Line Set 12. . . . . . . . . . . . . . . . . .
Brazing Connections 14. . . . . . . . . . . . . . . . . . . . . . . . . . .
Flushing the System 17. . . . . . . . . . . . . . . . . . . . . . . . . . .
Leak Testing the System 19. . . . . . . . . . . . . . . . . . . . . . .
Evacuating the System 19. . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Field Control Wiring 24. . . . . . . . . . . . . . . . . . . . . . . . . . .
Servicing Unit Delivered Void of Charge 26. . . . . . . . . .
Unit Start−Up 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Refrigerant 26. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Handler / Indoor Coil Match ups and Targeted
Subcooling Values 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating and Temperature Pressures 30. . . . . . . . . .
III. SYSTEM OPERATION AND SERVICE
OUTDOOR CONTROL − PART NUMBER 101796−XX
Heat Pump Control (A175) Jumpers and Terminals 31
System Status, Fault and Lockout LED Codes 33. . . .
Component Field Configuration and
Troubleshooting 38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OUTDOOR CONTROL − PART NUMBER 103369−XX
Jumpers and Links 47. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring Unit 48. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7−Segment Alert and System Status Codes 51. . . . . . .
Reconfiguring Outdoor Control using icomfort
Thermostat 51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
APPLICABLE TO ALL VERSIONS
Compressor Information and Testing 57. . . . . . . . . . . . .
System Overview 61. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defrost System 61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance 67. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SunSource
®
Home Energy System 67. . . . . . . . . . . . . .
Checklists 68. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Wiring Diagrams 69. . . . . . . . . . . . . . . . . . . . . . . . . .
Factory Wiring Diagrams 72. . . . . . . . . . . . . . . . . . . . . . .
Unit Sequence of Operations 75. . . . . . . . . . . . . . . . . . .
Page 2
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XP21
I. OVERVIEW
Model Number identification
P 21 XXX− −
Unit Type
P = Heat Pump
Series
Nominal Cooling Capacity
024 = 2 tons
036 = 3 tons
048 = 4 tons
060 = 5 tons
Minor Revision Number
230
Voltage
230 = 208/230V−1ph−60hz
Refrigerant Type
X = R−410A
X
−02
Typical Serial Number Identification
8 09 C
Year Code
08 = 2008
09 = 2009
10 = 2010
Month Code
A = January
B = February
C = March
05716
5 (or 6) Digit Unique Number
Location Code
19 = Saltillo, Mexico
58 = Marshalltown, IA
5
Specifications
Model Number
Unit Outdoor Fan
Sound Rating Number
(dB)
1
Factory Refrigerant
Charge
2
Number of Blades Diameter − inches.
XP21−024−230−01, −02, −03, −04, −05 67 11 lbs. 0 oz. 5 26.1
Model Number
Unit Outdoor Fan
Sound Rating Number
(dB)
1
Factory Refrigerant
Charge
2
Number of Blades Diameter − inches.
XP21−036−230−01, −02, −03, −04 72 11 lbs. 0 oz. 5 26.1
Model Number
Sound Rating Number
(dB)
1
Factory Refrigerant
Charge
2
Number of Blades Diameter − inches.
XP21−048−230−01, −02, −03 73 14 lbs. 0 oz. 5 26.1
XP21−048−230−04 73 13 lbs. 0 oz. 5 26.1
Model Number
Sound Rating Number
(dB)
1
Factory Refrigerant
Charge
2
Number of Blades Diameter − inches.
XP21−060−230−01, −02, −03 73 14 lbs. 4 oz. 5 26.1
XP21−060−230−04 73 13 lbs. 2 oz. 5 26.1
1
Tested according to AHRI Standard 270−2008 test conditions.
2
Refrigerant charge sufficient for 15 feet length of refrigerant lines.
Page 3
Page 3
XP21
Electrical Data
208/230V−60 Hz−1 Ph
Model Number
Unit Compressor Condenser Fan
Maximum
Over−
current
Protection
(amps)
1
Minimum
Circuity
Ampacity
2
Rated Load
Amps (RLA)
Locked
Rotor
Amps
(LRA)
Motor HP
Nominal
RPM 1−Stage
Nominal
RPM 2−Stage
Full Load
Amps (FLA)
XP21−024−230−01,
−02, −03, −04, −05
25 14.9 10.3 51.0 1/3 430 500 2.0
XP21−024−230−05 25 16.6 11.7 58.0 1/3 430 500 2.0
208/230V−60 Hz−1 Ph
Model Number
Unit Compressor Condenser Fan
Maximum
Over−
current
Protection
(amps)
1
Minimum
Circuity
Ampacity
2
Rated Load
Amps (RLA)
Locked
Rotor
Amps
(LRA)
Motor HP
Nominal
RPM 1−Stage
Nominal
RPM 2−Stage
Full Load
Amps (FLA)
XP21−036−230−01,
−02, −03
35 22.9 16.7 82.0 1/3 525 600 2.0
XP21−036−230−04 35 21.1 15.3 83.0 1/3 525 600 2.0
208/230V−60 Hz−1 Ph
Model Number
Unit Compressor Condenser Fan
Maximum
Over−
current
Protection
(amps)
1
Minimum
Circuity
Ampacity
2
Rated Load
Amps (RLA)
Locked
Rotor
Amps
(LRA)
Motor HP
Nominal
RPM 1−Stage
Nominal
RPM 2−Stage
Full Load
Amps (FLA)
XP21−048−230−01,
−02, −03
45 28.5 21.2 96.0 1/3 600 675 2.0
XP21−048−230−04 45 28.5 21.2 104.0 1/3 600 675 2.0
208/230V−60 Hz−1 Ph
Model Number
Unit Compressor Condenser Fan
Maximum
Over−
current
Protection
(amps)
1
Minimum
Circuity
Ampacity
2
Rated Load
Amps (RLA)
Locked
Rotor
Amps
(LRA)
Motor HP
Nominal
RPM 1−Stage
Nominal
RPM 2−Stage
Full Load
Amps (FLA)
XP21−060−230−01 50 34.1 25.7 118.0 1/3 625 700 2.0
XP21−060−230−02,
−03
50 30.9 23.1 118.0 1/3 625 700 2.0
XP21−060−230−04 60 38.0 28.8 153.0 1/3 625 700 2.0
1
HACR type circuit breaker or fuse.
2
Refer to National or Canadian Electrical Code manual to determine wire, fuse and disconnect size requirements.
Page 4
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XP21
Unit Dimensions −− Inches (mm)
39−1/2
(1003)
1 (25)
LIQUID LINE
INLET
SIDE VIEW
ACCESS VIEW
DISCHARGE AIR
4−5/8
(117)
BASE WITH ELONGATED LEGS
16−7/8
(429)
8−3/4
(222)
26−7/8
(683)
3−3/4 (95)
30−3/4
(781)
3−1/8
(79)
SUCTION LINE
INLET
UNIT SUPPORT
FEET
35−1/2
(902)
18−1/2
(470)
8 (203)
4−1/2
(114)
ELECTRICAL INLET
(HIGH VOLTAGE)
37 (940) (−024 AND −036)
SOLAR MODULE
WIRING
ELECTRICAL INLET
(CONTROL WIRING −
LOW VOLTAGE)
47 (1194) (−048 AND −060)
Page 5
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XP21
Typical Unit Parts Arrangement
GROUND LUGS
HIGH VOLTAGE FIELD
CONNECTIONS
CONTACTOR−1POLE
(K1−1)
HEAT PUMP CONTROL (A175)
CAPACITOR (C12)
FAN MOTOR CONTROL (A177) PULSE−WIDTH
MODULATION (PWM) (ONLY ON UNITS WITH MAIN
CONTROL 101796−XX)
WIRE TIE
RT13 OUTDOOR
AMBIENT
TEMPERATURE
SENSOR
VAPOR VALVE
AND GAUGE
PORT
REVERSING
VALV E
LIQUID LINE BI−FLOW
FILTER DRIER
HIGH PRESSURE
SWITCH (S4)
LIQUID VALVE AND
GAUGE PORT
TRUE SUCTION LINE
PORT
LOW PRESSURE
SWITCH (S87)
CRANKCASE HEATER THERMOSTAT (S40)
HR1 CRANKCASE HEATER
COMPRESSOR
MUFFLER
DISCHARGE LINE
CHECK
EXPANSION VALVE
DISCHARGE LINE
TEMPERATURE SENSOR
(RT28)
COIL TEMPERATURE SENSOR (RT21) − ON
RETURN BEND, 12 TUBES UP FROM
BOTTOM (11.50’ UP)
XP21−024 AND −036
XP21−048 AND −060
COIL TEMPERATURE
SENSOR (RT21) − ON
RETURN BEND, 24
TUBES UP FROM
BOTTOM (23.50’ UP)
FAN MOTOR SURGE PROTECTION (ONLY
ON XP21−XXX−230−01 BUILD. STARTING
WITH BUILD −02, SURGE PROTECTION
BUILT INTO FAN MOTOR)
Figure 1. Plumbing, Switches and Sensor Components
Page 6
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XP21
IMPORTANT
This unit must be matched with an indoor coil as
specified in Lennox’ Engineering Handbook. Coils
previously charged with HCFC−22 must be flushed.
WARNING
This product and/or the indoor unit it is matched with may
contain fiberglass wool.
Disturbing the insulation during installation,
maintenance, or repair will expose you to fiberglass wool
dust. Breathing this may cause lung cancer. (Fiberglass
wool is known to the State of California to cause cancer.)
Fiberglass wool may also cause respiratory, skin, and
eye irritation.
To reduce exposure to this substance or for further
information, consult material safety data sheets available
from address shown below, or contact your supervisor.
Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379−9900
CAUTION
Physical contact with metal edges and corners while
applying excessive force or rapid motion can result in
personal injury. Be aware of, and use caution when
working 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.
Operating Gauge Set
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.
IMPORTANT
Only use Allen wrenches of sufficient hardness (50Rc −
Rockwell Harness Scale minimum). Fully insert the
wrench into the valve stem recess.
Service valve stems are factory−torqued (from 9 ft−lbs for
small valves, to 25 ft−lbs for large valves) to prevent
refrigerant loss during shipping and handling. Using an
Allen wrench rated at less than 50Rc risks rounding or
breaking off the wrench, or stripping the valve stem
recess.
See the Lennox Service and Application Notes #C−08−1
for further details and information.
IMPORTANT
To prevent stripping of the various caps used, the
appropriately sized wrench should be used and fitted
snugly over the cap before tightening.
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 set used with HFC−410A refrigerant systems must be capable of handling the higher system
operating pressures. The gauges should be rated for use
with pressures of 0 − 800 psig on the high side and a low
side of 30" vacuum to 250 psig with dampened speed to
500 psi. Gauge hoses must be rated for use at 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 2 provides information on
how to access and operating both angle and ball service
valves.
General
The XP21 is a high efficiency residential split−system heat
pump unit, which features a two−stage scroll compressor
and HFC−410A refrigerant. Units are available in 2, 3, 4 and
5−ton sizes. The series is designed for use with an expansion valve only (approved for use with HFC−410A) in the
indoor unit.
Page 7
Page 7
XP21
(VALVE STEM SHOWN
CLOSED) INSERT HEX
WRENCH HERE
SERVICE PORT CORE
SERVICE PORT CAP
ANGLE−TYPE SERVICE VALVE
(FRONT−SEATED CLOSED)
TO OUTDOOR UNIT
STEM CAP
(VALVE STEM SHOWN OPEN)
INSERT HEX WRENCH HERE
TO INDOOR
UNIT
ANGLE−TYPE SERVICE VALVE
(BACK−SEATED OPENED)
BALL (SHOWN
CLOSED)
SERVICE PORT
CORE
TO INDOOR UNIT
TO OUTDOOR
UNIT
TO OPEN ROTATE STEM
COUNTERCLOCKWISE 90°.
TO CLOSE ROTATE STEM
CLOCKWISE 90°.
SERVICE PORT
SERVICE PORT
CAP
STEM CAP
VALV E
STEM
SERVICE VALVES
ANGLE AND BALL
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.
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°.
1
2
3
4
5
6
7
8
9
10
11
12
1/12 TURN
To Access Service Port:
A service port cap protects the service port core from contamination and
serves as the primary leak seal.
1. Remove service port cap with an appropriately sized wrench.
2. Connect gauge set to service port.
3. When testing is completed, replace service port cap and tighten as
follows:
With torque wrench: Finger tighten and
torque cap per table 1.
Without torque wrench: Finger tighten and
use an appropriately sized wrench to turn
an additional 1/6 turn clockwise.
1
2
3
4
5
6
7
8
9
10
11
12
1/6 TURN
WHEN SERVICE VALV E IS CLOSED, THE SERVICE PORT IS
OPEN
TO THE LINE SET AND INDOOR UNIT.
When service valve is OPEN, the service port is
open to linE set, indoor and outdoor unit.
Reinstall Stem Cap:
Stem cap protects the valve stem from damage and serves as the
primary seal. Replace the stem cap and tighten as follows:
With Torque Wrench: Finger tighten and then
torque cap per table 1.
Without Torque Wrench: Finger tighten and
use an appropriately sized wrench to turn an
additional 1/12 turn clockwise.
NOTE A label with specific torque requirements may be affixed to the stem cap. If the label is present, use the specified torque.
Figure 2. Angle and Ball Service Valves
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Page 8
XP21
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 3 for mandatory
installation clearance requirements.
POSITIONING CONSIDERATIONS
Consider the following when positioning the unit:
Some localities are adopting sound ordinances based
on the unit’s sound level registered from the adjacent
property, not from the installation property. Install the
unit as far as possible from the property line.
When possible, do not install the unit directly outside
a window. Glass has a very high level of sound transmission. For proper placement of unit in relation to a
window see the provided illustration in figure 5, 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 5, detail B.
NOTE If necessary for stability, anchor unit to slab as described in figure 5, detail D.
ELEVATING THE UNIT
Units are outfitted with elongated support feet as illustrated
in figure 5, detail C.
If additional elevation is necessary, raise the unit by extending the height of the unit support feet. This may be
achieved by using a 2−inch (50.8mm) Schedule 40 female
threaded adapter.
The specified coupling will fit snuggly 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
further, consider a different type of field−fabricated framework that is sturdy enough for greater heights.
CONTROL PANEL
ACCESS
LOCATION
6 (152)
36 (914)
12 (305)
30 (762)
LINE SET
CONNECTIONS
24 (610)
LINE SET
CONNECTIONS
ACCESS PANEL
REAR VIEW OF UNIT
48 (1219)
MINIMUM CLEARANCE BETWEEN
TWO UNITS
CLEARANCE ON ALL SIDES INCHES (MILLIMETERS)
ACCESS PANEL
MINIMUM CLEARANCE
ABOVE UNIT
NOTES:
CLEARANCE TO ONE OF THE
OTHER 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).
Figure 3. Installation Clearances
Page 9
Page 9
XP21
STABILIZING UNIT ON UNEVEN SURFACES
IMPORTANT
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 two side louvered panels to expose the unit
base.
2. Install the brackets as illustrated in figure 5, 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 absorbed 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.
Install the unit a minimum of six inches (152 mm) above the
roof surface to avoid ice build−up around the unit. Locate
the unit above a load bearing wall or area of the roof that
can adequately support the unit. Consult local codes for
rooftop applications.
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.
24"
(610)
WIND BARRIER
PREVAILING WINTER
WINDS
INLET AIR
INLET AIR
INLET AIR
Figure 4. Rooftop Application and Wind Barrier
Page 10
Page 10
XP21
LEG DETAIL
BASE
2" (50.8MM) SCH 40
FEMALE THREADED
ADAPTER
ONE BRACKET PER SIDE (MIN.); FOR EXTRA STABILITY, TWO
BRACKETS PER SIDE, 2" (50.8MM) FROM EACH CORNER.
CONCRETE SLAB USE TWO PLASTIC
ANCHORS (HOLE DRILL 1/4")
COIL
BASE PAN
CORNER POST
STABILIZING BRACKET (18 GAUGE
METAL 2" WIDTH; HEIGHT AS
REQUIRED)
Slab Side Mounting
#10 1/2" LONG SELF−DRILLING
SHEET METAL SCREWS
#10 1−1/4" LONG HEX HD SCREW
AND FLAT WASHER
MINIMUM ONE
PER SIDE
STABILIZING BRACKET (18 GAUGE METAL
2" (50.8MM) WIDTH; HEIGHT AS
REQUIRED); BEND TO FORM RIGHT ANGLE
FOR EXTRA
STABILITY
Deck Top Mounting
Elevated Slab Mounting using Feet
Extenders
Stabilizing Unit on Uneven Surfaces
WOOD OR PLASTIC SLAB NO PLASTIC ANCHOR
(HOLE DRILL 1/8")
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.
MOUNTING
SLAB
BUILDING
STRUCTURE
GROUND LEVEL
Outside Unit Placement
Slab Mounting at Ground Level
SAME FASTENERS AS
SLAB SIDE MOUNTING.
IMPORTANT To help stabilize an outdoor unit, some installations may require
strapping the unit to the pad using brackets and anchors commonly available in the
marketplace.
DETAIL A
DETAIL B
DETAIL C
DETAIL D
2" (50.8MM) SCH 40
MALE THREADED
ADAPTER
USE ADDITIONAL 2" SCH 40 MALE THREADED ADAPTERS WHICH CAN BE THREADED INTO THE FEMALE
THREADED ADAPTERS TO MAKE ADDITIONAL ADJUSTMENTS TO THE LEVEL OF THE UNIT.
TWO 90° ELBOWS INSTALLED IN LINE SET WILL
REDUCE LINE SET VIBRATION.
INSTALL UNIT AWAY FROM WINDOWS
Figure 5. Placement and Slab Mounting
Page 11
Page 11
XP21
Removing and Installing Panels
REMOVE 4 SCREWS TO
REMOVE PANEL FOR
ACCESSING COMPRESSOR
AND CONTROLS.
POSITION PANEL WITH HOLES
ALIGNED; INSTALL SCREWS
AND TIGHTEN.
ACCESS PANEL REMOVAL
REMOVAL AND RE−INSTALLATION OF THE
ACCESS PANEL IS AS ILLUSTRATED.
Detail A
Detail B
ROTATE IN THIS DIRECTION; THEN
DOWN TO REMOVE PANEL
SCREW
HOLES
LIP
PANEL SHOWN SLIGHTLY ROTATED TO ALLOW TOP TAB TO EXIT (OR ENTER) TOP SLOT FOR
REMOVING (OR INSTALLING) PANEL.
MAINTAIN MINIMUM PANEL ANGLE (AS CLOSE TO PARALLEL WITH THE UNIT AS
POSSIBLE) WHILE INSTALLING PANEL.
PREFERRED ANGLE FOR INSTALLATION
Detail D
ANGLE MAY BE TOO EXTREME
HOLD DOOR FIRMLY ALONG
THE HINGED SIDE TO MAINTAIN
FULLY−ENGAGED TABS
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.
PANELS
ACCESS AND LOUVERED
IMPORTANT Do not allow panels to hang on unit by top tab.
Tab is for alignment and not designed to support weight of panel.
IMPORTANT To help stabilize an outdoor unit, some installations
may require strapping the unit to the pad using brackets and anchors
commonly available in the marketplace.
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.
WARNING
Detail C
Figure 6. Removing and Installing Panels
Page 12
Page 12
XP21
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 14.
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 17.
If refrigerant lines are routed through a wall, then 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 7 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 2 may be reused. If system
was previously charged with HCFC−22 refrigerant, then existing line set must be flushed (see Flushing the System on
page 17).
Field refrigerant piping consists of liquid and vapor lines
from the outdoor unit to the indoor unit coil (braze connections). Use Lennox L15 (sweat, non−flare) series line set, or
field−fabricated refrigerant line sizes as listed in table 2.
Table 2. Refrigerant Line Set
Models Liquid
Line
Vapor/
Suction
Line
L15 Line Set
−024, −036
and−048
3/8 (10) 7/8 (22) L15 line set sizes are
dependent on unit match
up. See XP21 Engineering
Handbook to determine
correct line set sizes.
−060 3/8 (10) 1−1/8 (29) Field Fabricated
NOTE Some applications may required a field−provided 7/8" to
1−1/8" adapter.
NOTE When installing refrigerant lines longer than 50
feet, see the Lennox Refrigerant Piping Design and Fabrication Guidelines, or contact Lennox Technical Support
Product Applications for assistance. To obtain the correct
information from Lennox, be sure to communicate the following points:
Model (XP21) and size of unit (e.g. −036).
Line set diameters for the unit being installed as listed
in table 2 and total length of installation.
Number of elbows vertical rise or drop in the piping.
IMPORTANT
Mineral oils are not compatible with HFC−410A. If oil must
be added, it must be a Polyol ester oil.
The compressor is charged with sufficient Polyol ester oil
for line set lengths up to 50 feet. Recommend adding oil to
system based on the amount of refrigerant charge in the
system. No need to add oil in system with 20 pounds of refrigerant or less. For systems over 20 pounds − add one
ounce of every five pounds of refrigerant.
Recommended topping−off POE oils are Mobil EAL ARCTIC 22 CC or ICI EMKARATE 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).
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.
Page 13
Page 13
XP21
ANCHORED HEAVY NYLON
WIRE TIE OR AUTOMOTIVE
MUFFLER-TYPE HANGER
STRAP LIQUID LINE TO
VAPOR LINE
WALL
STUD
LIQUID LINE
NON−CORROSIVE
METAL SLEEVE
VAPOR LINE − WRAPPED
IN ARMAFLEX
AUTOMOTIVE
MUFFLER-TYPE HANGER
REFRIGERANT LINE SET TRANSITION
FROM VERTICAL TO HORIZONTAL
LINE SET ISOLATION THE FOLLOWING ILLUSTRATIONS ARE EXAM-
PLES OF PROPER REFRIGERANT LINE SET ISOLATION:
STRAPPING
MATERIAL (AROUND
VAPOR LINE ONLY)
TAPE OR
WIRE TIE
WIRE TIE (AROUND
VAPOR LINE ONLY)
FLOOR JOIST OR
ROOF RAFTER
TAPE OR
WIRE TIE
TO HANG LINE SET FROM JOIST OR RAFTER, USE EITHER METAL
STRAPPING MATERIAL OR ANCHORED HEAVY NYLON WIRE TIES.
8 FEET (2.43 METERS)
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.
FLOOR JOIST OR
ROOF RAFTER
REFRIGERANT LINE SET INSTALLING
HORIZONTAL RUNS
NOTE SIMILAR INSTALLATION PRACTICES SHOULD BE USED IF
LINE SET IS TO BE INSTALLED ON EXTERIOR OF OUTSIDE WALL.
PVC
PIPE
FIBERGLASS
INSULATION
CAULK
OUTSIDE
WALL
VAPOR LINE WRAPPED
WITH ARMAFLEX
LIQUID
LINE
OUTSIDE WALL
LIQUID LINE
VAPOR LINE
WOOD BLOCK
BETWEEN STUDS
STRAP
WOOD BLOCK
STRAP
SLEEVE
WIRE TIE
WIRE TIE
WIRE TIE
INSIDE WALL
REFRIGERANT LINE SET INSTALLING
VERTICAL RUNS (NEW CONSTRUCTION SHOWN)
INSTALLATION
LINE SET
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.
NON−CORROSIVE
METAL SLEEVE
IMPORTANT Refrigerant lines must not contact structure.
NON−CORROSIVE
METAL SLEEVE
8 FEET (2.43 METERS)
IMPORTANT Refrigerant lines must not contact
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.
Figure 7. Line Set Installation
Page 14
Page 14
XP21
Brazing Connections
Use the procedures outline in figures 8 and 9 for brazing
line set connections to service valves.
WARNING
Danger of fire. Bleeding the refrigerant
charge from only the high side may result
in pressurization of the low side shell and
suction tubing. Application of a brazing
torch to a pressurized system may result
in ignition of the refrigerant and oil mixture
− Check the high and low pressures
before applying heat.
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.
IMPORTANT
Connect gauge set low pressure side to vapor line
service valve and repeat procedure starting at
paragraph 4 for brazing the liquid line to service port
valve.
IMPORTANT
Allow braze joint to cool before removing the wet rag
from the service valve. Temperatures above 250ºF can
damage valve seals.
IMPORTANT
Use silver alloy brazing rods with 5% minimum silver
alloy for copper−to−copper brazing. Use 45% minimum
alloy for copper−to−brass and copper−to−steel brazing.
WARNING
Fire, Explosion and Personal Safety
Hazard.
Failure to follow this warning could
result in damage, personal injury or
death.
Never use oxygen to pressurize or
purge refrigeration lines. Oxygen,
when exposed to a spark or open
flame, can cause fire and/or an explosion, that could result in property
damage, personal injury or death.
Page 15
Page 15
XP21
ATTACH THE MANIFOLD GAUGE SET FOR BRAZING
LIQUID AND SUCTION LINE SERVICE VALVES
OUTDOOR
UNIT
LIQUID LINE
SUCTION LINE
LIQUID LINE SERVICE
VALV E
SUCTION LINE
SERVICE VALVE
ATTACH
GAUGES
INDOOR
UNIT
SUCTION SERVICE PORT MUST BE OPEN AND
SERVICE PORT CORE REMOVED TO ALLOW
EXIT POINT FOR NITROGEN FLOW
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 With valve core removed from the suction line service
port, nitrogen flow will have an exit point.
NITROGEN
HIGH
LOW
B
A
C
PIPING PANEL REMOVAL AND PREPARING LINE
SET
CAP AND CORE REMOVAL
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.
Remove service cap and core from both the suction and liquid line
service ports.
1
2
LIQUID LINE SERVICE VALVE
SERVICE PORT
CORE
SERVICE PORT CAP
SERVICE PORT
CORE
SERVICE
PORT CAP
CUT AND DEBUR
LINE SET SIZE MATCHES
SERVICE VALVE CONNECTION
COPPER TUBE
STUB
SERVICE VALVE
CONNECTION
REFRIGERANT LINE
DO NOT CRIMP SERVICE
VALVE CONNECTOR WHEN
PIPE IS SMALLER THAN
CONNECTION
REDUCER
3
SUCTION LINE SERVICE
VALV E
LINE SET SIZE IS SMALLER
THAN CONNECTION
Figure 8. Brazing Procedures
Page 16
Page 16
XP21
BRAZE LINE SET
Water saturated cloths must remain water saturated
throughout the brazing and cool−down process.
6
After all connections have been brazed, disconnect manifold gauge set from service ports. Apply additional water saturated 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.
PREPARATION FOR NEXT STEP
7
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 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.
5
SUCTION / VAPOR LINE
WHEN BRAZING LINE SET TO
SERVICE VALVES, POINT FLAME
AWAY FROM SERVICE VALVE.
WARNING
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.
LIQUID LINE
WATER SATURATED
CLOTHS
WATER SATURATED CLOTHS
A Braze liquid line to liquid line service valve.
B Braze suction / vapor line to suction / vapor service
valve.
6A
6B
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.
Figure 9. Brazing Procedures (Continued)
Page 17
Page 17
XP21
Flushing the System
SENSING
LINE
TEFLON® RING
FIXED ORIFICE
BRASS NUT
LIQUID LINE ASSEMBLY
(INCLUDES STRAINER)
LIQUID LINE ORIFICE HOUSING
DISTRIBUTOR TUBES
DISTRIBUTOR
ASSEMBLY
REMOVE AND DISCARD
WHITE TEFLON
®
SEAL
(IF PRESENT)
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 DISTRIBUTOR TUBES DURING THIS PROCESS.
D REMOVE AND DISCARD FIXED ORIFICE, VALVE STEM ASSEMBLY IF
PRESENT AND TEFLON
®
WASHER AS ILLUSTRATED ABOVE.
E USE A FIELD−PROVIDED FITTING TO TEMPORARY RECONNECT THE
LIQUID LINE TO THE INDOOR UNIT’S LIQUID LINE ORIFICE HOUSING.
TYPICAL EXISTING FIXED ORIFICE
REMOVAL PROCEDURE (UNCASED COIL
SHOWN)
TYPICAL EXISTING EXPANSION VALVE
REMOVAL PROCEDURE (UNCASED COIL
SHOWN)
TWO PIECE PATCH PLATE
(UNCASED COIL ONLY)
VAPOR
LINE
DISTRIBUTOR
ASSEMBLY
DISTRIBUTOR
TUBES
LIQUID
LINE
MALE EQUALIZER
LINE FITTING
EQUALIZER
LINE
CHECK
EXPANSION
VALV E
TEFLON
®
RING
STUB END
TEFLON
®
RING
SENSING BULB
LIQUID LINE
ORIFICE
HOUSING
LIQUID LINE
ASSEMBLY WITH
BRASS NUT
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 DISCONNECT THE EQUALIZER LINE FROM THE CHECK EXPANSION
VALVE EQUALIZER LINE FITTING ON THE VAPOR LINE.
D REMOVE THE VAPOR LINE SENSING BULB.
E DISCONNECT THE LIQUID LINE FROM THE CHECK EXPANSION VALVE
AT THE LIQUID LINE ASSEMBLY.
F DISCONNECT THE CHECK EXPANSION VALVE FROM THE LIQUID LINE
ORIFICE HOUSING. TAKE CARE NOT TO TWIST OR DAMAGE DISTRIBUTOR TUBES DURING THIS PROCESS.
G REMOVE AND DISCARD CHECK EXPANSION VALVE AND THE TWO TEF-
LON
®
RINGS.
H USE A FIELD−PROVIDED FITTING TO TEMPORARY RECONNECT THE
LIQUID LINE TO THE INDOOR UNIT’S LIQUID LINE ORIFICE HOUSING.
LOW
HIGH
EXISTING
INDOOR
UNIT
GAUGE
MANIFOLD
INV ERTED HCFC−22
CYLINDER CONTAINS
CLE AN HCFC−22 TO BE
USED FOR FLUSHING.
LIQUID LINE SERVICE
VALV E
INLET
DISCHARGE
TANK
RETURN
CLOSED
OPENED
RECOVERY
CYLINDER
RECOVERY MACHINE
NEW
OUTDOOR
UNIT
VAPOR LINE
SERVICE VALVE
VAPOR
LIQUID
1
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.
CONNECT GAUGES AND EQUIPMENT FOR
FLUSHING PROCEDURE
A
B
C
D
B
OR
FLUSHING LINE SET
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 VACUUM ON THE EXISTING SYSTEM LINE SET AND INDOOR UNIT COIL.
B INVERT THE CYLINDER OF CLEAN HCFC−22 AND OPEN ITS VALVE
TO ALLOW LIQUID REFRIGERANT TO FLOW INTO THE SYSTEM
THROUGH THE VAPOR LINE VALVE. ALLOW THE REFRIGERANT
TO PASS FROM THE CYLINDER AND THROUGH THE LINE SET
AND THE INDOOR UNIT COIL BEFORE IT ENTERS THE RECOVERY
MACHINE.
C AFTER ALL OF THE LIQUID REFRIGERANT HAS BEEN 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 DOWN TO 0 THE SYSTEM.
D CLOSE THE VALVE ON THE INVERTED HCFC−22 DRUM AND THE
GAUGE SET VALVES. PUMP THE REMAINING REFRIGERANT OUT
OF THE RECOVERY MACHINE AND TURN THE MACHINE OFF.
THE LINE SET AND INDOOR UNIT COIL MUST BE FLUSHED WITH AT
LEAST THE SAME AMOUNT OF CLEAN REFRIGERANT THAT PREVIOUSLY CHARGED THE SYSTEM. CHECK THE CHARGE IN THE
FLUSHING CYLINDER BEFORE PROCEEDING.
LINE SET AND INDOOR COIL (1 OF 2)
1A
2
3
CAUTION This procedure should not be performed on sys-
tems which contain contaminants (Example compressor burn
out.
1B
Page 18
Page 18
XP21
A ATTACH THE VAPOR LINE SENSING BULB IN THE PROPER
ORIENTATION AS ILLUSTRATED TO THE RIGHT USING THE
CLAMP AND SCREWS PROVIDED.
NOTE CONFIRM PROPER THERMAL CONTACT BETWEEN VAPOR LINE AND CHECK EXPANSION BULB BEFORE INSULATING
THE SENSING BULB ONCE INSTALLED.
B CONNECT THE EQUALIZER LINE
FROM THE CHECK EXPANSION
VALVE TO THE EQUALIZER VAPOR
PORT ON THE VAPOR LINE. FINGER TIGHTEN THE FLARE NUT
PLUS 1/8 TURN (7 FT−LBS) AS ILLUSTRATED BELOW.
THE CHECK EXPANSION VALVE UNIT CAN BE INSTALLED
INTERNAL OR EXTERNAL TO THE INDOOR COIL. IN
APPLICATIONS WHERE AN UNCASED COIL IS BEING INSTALLED
IN A FIELD−PROVIDED PLENUM, INSTALL THE CHECK
EXPANSION VALVE IN A MANNER THAT WILL PROVIDE ACCESS
FOR FIELD SERVICING OF THE CHECK EXPANSION VALVE.
REFER TO BELOW ILLUSTRATION FOR REFERENCE DURING
INSTALLATION OF CHECK EXPANSION VALVE UNIT.
TYPICAL NEW CHECK EXPANSION VALVE INSTALLATION PROCEDURE
TWO PIECE
PATCH PLATE
(UNCASED
COIL ONLY)
VAPOR
LINE
LIQUID LINE
ORIFICE
HOUSING
DISTRIBUTOR
TUBES
LIQUID LINE
MALE EQUALIZER LINE
FITTING (SEE
EQUALIZER LINE
INSTALLATION FOR
FURTHER DETAILS)
SENSING
LINE
EQUALIZER
LINE
CHECK
EXPANSION
VALV E
TEFLON
®
RING
(Uncased Coil Shown)
SENSING BULB INSULATION IS REQUIRED
IF MOUNTED EXTERNAL TO THE COIL
CASING. SENSING BULB INSTALLATION
FOR BULB POSITIONING.
STUB
END
TEFLON
®
RING
LIQUID LINE
ASSEMBLY WITH
BRASS NUT
DISTRIBUTOR
ASSEMBLY
THIS OUTDOOR UNIT IS DESIGNED FOR USE IN SYSTEMS THAT USE CHECK EXPANSION VALVE METERING DEVICE. SEE THE LENNOX XP21 ENGI-
NEERING HANDBOOK FOR APPROVED CHECK EXPANSION VALVE KIT MATCH−UPS AND APPLICATION INFORMATION.
A REMOVE THE FIELD−PROVIDED FITTING THAT TEMPORARY RECON-
NECTED THE LIQUID LINE TO THE INDOOR UNIT’S DISTRIBUTOR ASSEMBLY.
B INSTALL ONE OF THE PROVIDED TEFLON
®
RINGS AROUND THE
STUBBED END OF THE CHECK EXPANSION VALVE AND LIGHTLY LUBRICATE THE CONNECTOR THREADS AND EXPOSE SURFACE OF THE TEFLON
®
RING WITH REFRIGERANT OIL.
C ATTACH THE STUBBED END OF THE CHECK EXPANSION VALVE TO THE
LIQUID LINE ORIFICE HOUSING. FINGER TIGHTEN AND USE AN APPROPRIATELY SIZED WRENCH TO TURN AN ADDITIONAL 1/2 TURN CLOCKWISE AS ILLUSTRATED IN THE FIGURE ABOVE, OR 20 FT−LB.
D PLACE THE REMAINING TEFLON
®
WASHER AROUND THE OTHER END
OF THE CHECK EXPANSION VALVE. LIGHTLY LUBRICATE CONNECTOR
THREADS AND EXPOSE SURFACE OF THE TEFLON
®
RING WITH RE-
FRIGERANT OIL.
E ATTACH THE LIQUID LINE ASSEMBLY TO THE CHECK EXPANSION VALVE.
FINGER TIGHTEN AND USE AN APPROPRIATELY SIZED WRENCH TO
TURN AN ADDITIONAL 1/2 TURN CLOCKWISE AS ILLUSTRATED IN THE
FIGURE ABOVE OR 20 FT−LB.
ON 7/8" AND LARGER LINES,
MOUNT SENSING BULB AT
EITHER THE 4 OR 8 O’CLOCK
POSITION. NEVER MOUNT ON
BOTTOM OF LINE.
12
ON LINES SMALLER THAN
7/8", MOUNT SENSING
BULB AT EITHER THE 3 OR
9 O’CLOCK POSITION.
12
BULB
VAPOR LINE
VAPOR LINE
NOTE NEVER MOUNT ON BOTTOM OF LINE.
BULB
BULB
BULB
VAPOR LINE
FLARE NUT
COPPER FLARE
SEAL BONNET
MALE BRASS EQUALIZER
LINE FITTING
FLARE SEAL CAP
OR
1
2
3
4
5
6
7
8
9
10
11
12
1/2 TURN
SENSING BULB INSTALLATION
EQUALIZER LINE INSTALLATION
1
2
3
4
5
6
7
8
9
10
11
12
1/8 TURN
FLUSHING LINE SET AND INDOOR COIL (2 OF 2)
4
A REMOVE AND DISCARD EITHER THE FLARE SEAL CAP OR
FLARE NUT WITH COPPER FLARE SEAL BONNET FROM
THE EQUALIZER LINE PORT ON THE VAPOR LINE AS ILLUSTRATED IN THE FIGURE TO THE RIGHT.
B REMOVE AND DISCARD EITHER THE FLARE SEAL CAP OR
FLARE NUT WITH COPPER FLARE SEAL BONNET FROM THE
EQUALIZER LINE PORT ON THE VAPOR LINE AS ILLUSTRATED IN THE FIGURE TO THE RIGHT.
Page 19
Page 19
XP21
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.
TWO ISOLATION GROMMETS ARE
PROVIDE FOR THE LIQUID AND
SUCTION LINE PIPE PANEL PASS
THROUGH.
LIQUID LINE
SUCTION LINE
REAR VIEW OF UNIT EXTERIOR
PIPING PANEL
Figure 10. 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
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.
Leak Testing the System
IMPORTANT
Leak detector must be capable of sensing HFC
refrigerant.
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
Hazard.
Failure to follow this warning could
result in damage, personal injury or
death.
Never use oxygen to pressurize or
purge refrigeration lines. Oxygen,
when exposed to a spark or open
flame, can cause damage by fire and/
or an explosion, that could result in
personal injury or death.
Page 20
Page 20
XP21
TO VAPOR
SERVICE VALVE
HFC−410A
MANIFOLD GAUGE SET
OUTDOOR UNIT
HIGH
LOW
NITROGEN
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.
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.
LINE SET AND INDOOR COIL
AFTER THE LINE SET HAS BEEN CONNECTED TO THE INDOOR AND OUTDOOR UNITS, CHECK THE LINE SET CONNECTIONS AND INDOOR UNIT FOR LEAKS. USE THE FOLLOWING PROCEDURE TO TEST FOR LEAKS:
LEAK TEST
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.
1
CONNECT GAUGE
SET
2
TEST FOR LEAKS
A
B
NOTE LATER IN THE PROCEDURE, THE HFC−410A
CONTAINER WILL BE REPLACED BY THE NITROGEN
CONTAINER.
Figure 11. System Leak Test
Page 21
Page 21
XP21
Evacuating the System
A OPEN BOTH MANIFOLD VALVES AND START THE VACUUM PUMP.
B EVACUATE THE LINE SET AND INDOOR UNIT TO AN ABSOLUTE PRESSURE OF 23,000 MICRONS (29.01 INCHES OF MERCURY).
NOTE DURING THE EARLY STAGES OF EVACUATION, IT IS DESIRABLE TO CLOSE THE MANIFOLD GAUGE VALVE AT LEAST ONCE. A RAPID
RISE IN PRESSURE INDICATES A RELATIVELY LARGE LEAK. IF THIS OCCURS, REPEAT THE LEAK TESTING PROCEDURE.
NOTE THE TERM ABSOLUTE PRESSURE MEANS THE TOTAL ACTUAL PRESSURE WITHIN A GIVEN VOLUME OR SYSTEM, ABOVE THE ABSO-
LUTE ZERO OF PRESSURE. ABSOLUTE PRESSURE IN A VACUUM IS EQUAL TO ATMOSPHERIC PRESSURE MINUS VACUUM PRESSURE.
C WHEN THE ABSOLUTE PRESSURE REACHES 23,000 MICRONS (29.01 INCHES OF MERCURY), CLOSE THE MANIFOLD GAUGE VALVES, TURN
OFF THE VACUUM PUMP AND DISCONNECT THE MANIFOLD GAUGE CENTER PORT HOSE FROM VACUUM PUMP. ATTACH THE MANIFOLD
CENTER PORT HOSE TO A DRY NITROGEN CYLINDER WITH PRESSURE REGULATOR SET TO 150 PSIG (1034 KPA) AND PURGE THE HOSE.
OPEN THE MANIFOLD GAUGE VALVES TO BREAK THE VACUUM IN THE LINE SET AND INDOOR UNIT. CLOSE THE MANIFOLD GAUGE VALVES.
D SHUT OFF THE DRY NITROGEN CYLINDER AND REMOVE THE MANIFOLD GAUGE HOSE FROM THE CYLINDER. OPEN THE MANIFOLD
GAUGE VALVES TO RELEASE THE DRY NITROGEN FROM THE LINE SET AND INDOOR UNIT.
E RECONNECT THE MANIFOLD GAUGE TO THE VACUUM PUMP, TURN THE PUMP ON, AND CONTINUE TO EVACUATE THE LINE SET AND 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:
OUTDOOR
UNIT
TO VAPOR
SERVICE VALVE
TO LIQUID LINE
SERVICE VALVE
MICRON
GAUGE
VACUUM PUMP
A34000 1/4 SAE TEE WITH
SWIVEL COUPLER
500
MANIFOLD
GAUGE SET
HFC−410A
RECOMMEND
MINIMUM 3/8" HOSE
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
VALV E
C CONNECT MICRON GAUGE AVAILABLE
CONNECTOR ON THE 1/4 SAE IN−LINE
TEE.
D CONNECT THE VACUUM PUMP (WITH
VACUUM GAUGE) TO THE CENTER
PORT OF THE MANIFOLD GAUGE SET.
THE CENTER PORT LINE WILL BE USED
LATER FOR BOTH THE HFC−410A AND
NITROGEN CONTAINERS.
HIGH
LOW
1
2
3
4
5
6
7
8
9
10
11
12
1/6 TURN
NITROGEN
1
CONNECT GAUGE SET
A
B
C
D
2
EVACUATE THE SYSTEM
CLOSE MANIFOLD GAUGE VALVES.
SHUT OFF HFC−410A CYLINDER.
REINSTALL SERVICE VALVE CORES BY REMOVING MANIFOLD HOSE FROM SERVICE VALVE. QUICKLY
INSTALL CORES WITH CORE TOOL WHILE MAINTAINING A POSITIVE SYSTEM PRESSURE.
REPLACE THE STEM CAPS AND SECURE FINGER TIGHT, THEN TIGHTEN AN ADDITIONAL ONE−SIXTH
(1/6) OF A TURN AS ILLUSTRATED.
LINE SET AND INDOOR COIL
NOTE REMOVE CORES FROM SERVICE VALVES (IF
NOT ALREADY DONE).
Figure 12. Evacuating System
Page 22
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XP21
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 de-
fined as any gas that will not condense under temperatures
and pressures present during operation of an air conditioning system. Non−condensables and water suction combine
with refrigerant to produce substances that corrode copper
piping and compressor parts.
Electrical
In the U.S.A., wiring must conform with current local codes
and the current National Electric Code (NEC). In Canada,
wiring must conform with current local codes and the current
Canadian Electrical Code (CEC).
Refer to the furnace or air handler installation instructions
for additional wiring application diagrams and refer to unit
nameplate for minimum circuit ampacity and maximum
overcurrent protection size.
24VAC TRANSFORMER
Use the transformer provided with the furnace or air handler for low-voltage control power (24VAC − 40 VA
minimum)
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.
NOTE UNITS ARE APPROVED FOR USE ONLY WITH COPPER
CONDUCTORS. GROUND UNIT AT DISCONNECT SWITCH OR TO AN
EARTH GROUND.
SIZE CIRCUIT AND INSTALL DISCONNECT
SWITCH
1
NOTE 24VAC, CLASS II CIRCUIT CONNECTIONS ARE MADE IN THE
CONTROL BOX.
INSTALL ROOM THERMOSTAT (ORDERED SEPARATELY) ON AN
INSIDE WALL APPROXIMATELY IN THE CENTER OF THE
CONDITIONED AREA AND 5 FEET (1.5M) FROM THE FLOOR. IT
SHOULD NOT BE INSTALLED ON AN OUTSIDE WALL OR WHERE IT
CAN BE AFFECTED BY SUNLIGHT OR DRAFTS.
THERMOSTAT
5 FEET
(1.5M)
INSTALL THERMOSTAT
2
SERVICE
DISCONNECT
SWITCH
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.
CAUTION
ELECTROSTATIC DISCHARGE
(ESD)
Precautions and Procedures
Electrostatic discharge can affect electronic components. Take precautions
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
Page 23
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XP21
NOTE FOR PROPER VOLTAGES, SELECT CONTROL WIRES GAUGE PER
TABLE BELOW.
WIRE RUN LENGTH AWG# INSULATION TYPE
LESS THAN 100’ (30 METERS) 18 TEMPERATURE RATING
MORE THAN 100’ (30 METERS) 16 35ºC MINIMUM.
NOTE WIRE TIE PROVIDES LOW VOLTAGE WIRE STRAIN RELIEF AND TO
MAINTAIN SEPARATION OF FIELD INSTALLED LOW AND HIGH VOLTAGE
CIRCUITS.
NOTE DO NOT BUNDLE ANY EXCESS 24VAC CONTROL WIRES INSIDE CONTROL BOX.
A. ROUTE CONTROL WIRES NON−COMMUNICATING
A
B
HEAT PUMP
CONTROL (A175)
CONTROL BOX
HOLE
INSTALL LOW VOLTAGE CONTROL WIRING FROM OUTDOOR TO INDOOR
UNIT AND FROM THERMOSTAT TO INDOOR UNIT AS ILLUSTRATED.
3
A RUN 24VAC CONTROL WIRES THROUGH HOLE WITH GROMMET.
B MAKE 24VAC CONTROL WIRE CONNECTIONS TO HEAT PUMP
CONTROL (A175) .
B. ROUTE CONTROL WIRES COMMUNICATING
MAXIMUM LENGTH OF WIRING (18 GAUGE) FOR ALL CONNECTIONS ON THE RSBUS IS LIMITED TO 1500 FEET (457 METERS). COLOR−CODED, TEMPERATURE
RATING 95
º
F (35ºC) MINIMUM, SOLID CORE. (CLASS II RATED WIRING)
ANY EXCESS HIGH VOLTAGE FIELD WIRING SHOULD BE TRIMMED AND SECURED AWAY FROM ANY LOW VOLTAGE FIELD WIRING. TO
FACILITATE A CONDUIT, A CUTOUT IS LOCATED IN THE BOTTOM OF THE CONTROL BOX. CONNECT CONDUIT TO THE CONTROL BOX USING
A PROPER CONDUIT FITTING.
ROUTE HIGH VOLTAGE AND GROUND WIRES
CONTROL BOX
PIPING PANEL
HIGH VOLTAGE
CONDUIT HOLE
GROUND LUG
CONTACTOR
WATERTIGHT
CONDUIT
FITTING
WATERTIGHT
FLEXIBLE
CONDUIT
TO AC DISCONNECT
BOX
ACCESS VIEW
ELECTRICAL INLET
(HIGH VOLTAGE)
WIRING ENTRY POINTS
ELECTRICAL INLET (CONTROL WIRING LOW VOLTAGE).
USE BUSHING PROVIDED IN BAG ASSEMBLY HERE.
4
Page 24
Page 24
XP21
Field Control Wiring
The following two illustrations provide examples on how to install control wiring using a non−communicating thermostat. For
examples of how to install control wiring in complete or partial communicating systems, see the icomfort thermostat Quick
Start Guide which is provided with the thermostat.
Y1
O
R
W1
G
D
R
Y1
L
C
C
ComfortSense[ 7000 Thermostats
Catalog # Y0349 or Y2081
B
Y2
Y2
W
O
DS
L
T
T
W2
H
W3
H
O
C
L
Y2
DS
DH
G
R
Y1
W2
W1
1
2
5
6
8
7
On−board link
Low voltage thermosta
t
wiring
Flat metal jumper
3
4
Air Handler Control
XP21 Two−Stage
Heat Pump Control
1. Thermostat T terminals are used for outdoor sensor input. Use for thermostat’s outdoor temperature display (optional).
2. R to L connection is required for this model when using the ComfortSense
®
7000 − catalog number Y0349 only. Resistor Kit (catalog number
47W97) required and ordered separately.
3. Air handler control ships from factory with metal jumpers installed across W1, W2 and W3. For one−stage electric heat, do not remove factory
installed metal jumpers.
4. Air handler control ships from factory with metal jumpers installed across W1, W2 and W3. For two−stage electric heat, remove factory installed
metal jumper between W1 to W2. Then connect thermostat wire between the air handler control’s W2 and the thermostat’s W2 terminal.
5. Cut on−board link (clippable wire) from R−O HEAT PUMP for heat pump applications.
6. Cut on−board link (clippable wire) from Y1−Y2 2 STAGE COMPR for two−stage compressor and two−speed fan operation.
7. Cut loop jumper (clippable wire) Short DS to R for Humiditrol
®
applications. This will slow the outdoor unit’s fan speed to a specific RPM. A wire
must be installed between the DS terminals on the air handler and outdoor unit controls. See table 17 for fan speed based on unit capacity.
8. Cut on−board link (clippable wire) DS−R for Humiditrol
®
or Harmony III applications. This will slow the indoor blower motor to the lowest speed
setting. See air handler installation instruction or engineering handbook for lowest fan speed information.
Figure 13. ComfortSense® 7000 Series Thermostat Air Hander/Two−Stage Heat Pump
Page 25
Page 25
XP21
Y1
O
R
W1
G
D
R
Y1
L
C
C
Furnace Control
ComfortSense[ 7000 Thermostats
Catalog # Y0349 or Y2081
XP21 Two−Stage
Heat Pump Control
B
Y2
Y2
W
O
DS
L
T
T
W2
H
W3
H
O
C
L
Y2
DS
DH
G
R
Y1
W2
W1
1
2
3
4
6
5
On−board link
Low voltage thermostat
wiring
1. Thermostat T terminals are used for outdoor sensor input. Use for thermostat’s outdoor temperature display (optional).
2. R to L connection is required for this model when using the ComfortSense
®
7000 − catalog number Y0349 only. Resistor Kit (catalog number
47W97) required and ordered separately.
3. Cut on−board link W951 (clippable wire) from R−O HEAT PUMP for heat pump applications.
4. Cut on−board link W915 (clippable wire) for two−stage operation.
5. Cut loop jumper (clippable wire) Short DS to R for Humiditrol
®
applications. This will slow the outdoor unit’s fan speed to a specific RPM. A wire
must be installed between the DS terminals on the furnace and outdoor unit controls. See table 17 for fan speed based on unit capacity.
6. Cut on−board link (clippable wire) DS−R for Humiditrol
®
or Harmony III applications. This will slow the indoor blower motor to the lowest speed
setting. See furnace installation instruction or engineering handbook for lowest fan speed information.
NOTE − For defrost temper with furnace, the optional 67M41 temper kit would be wired between W of from the heat pump control (A175) to the W1
of the furnace control The kit allows for the furnace to cycle on and off during a defrost. It protects the compressor from high refrigeration pressures
during defrost.
Figure 14. ComfortSense® 7000 Series Thermostat Furnace/Two−Stage Heat Pump
Page 26
Page 26
XP21
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
19.
2. Evacuate the system using procedure outlined on
page .
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 .
5. Weigh in refrigerant using procedure outlined in figure
17.
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
IMPORTANT
If unit is equipped with a crankcase heater, it should be
energized 24 hours before unit start−up to prevent
compressor damage as a result of slugging.
1. Rotate fan to check for binding.
2. Inspect all factory− and field−installed wiring for loose
connections.
3. After evacuation is complete, open 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 indoor unit and close the outdoor unit
disconnect switch to start the unit.
7. Recheck voltage while the unit is running. Power must
be within range shown on the nameplate.
8. Check system for sufficient refrigerant by using the
procedures listed under System Refrigerant.
System Refrigerant
This section outlines procedures for:
1. Connecting gauge set for testing and charging as illustrated in figure 15.
2. Checking and adjusting indoor airflow as described in
figure 16.
3. Add or remove refrigerant using the weigh in method
provided in figure 17, and verifying charge using subcooling method described in figure 18.
TO LIQUID
LINE SERVICE
VALV E
TEMPERATURE
SENSOR
DIGITAL SCALE
REFRIGERANT TANK
TEMPERATURE SENSOR
(LIQUID LINE)
MANIFOLD GAUGE SET
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.
OUTDOOR UNIT
CHARGE IN
LIQUID PHASE
CONNECTIONS FOR TESTING AND CHARGING
GAUGE SET
A
C
D
LOW
HIGH
B
INSIDE OUTDOOR UNIT
TRUE SUCTION PORT
CONNECTION
Figure 15. Gauge Set Connections
Page 27
Page 27
XP21
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 il-
lustration in figure 16.
HEATING MODE INDOOR AIRFLOW CHECK
Blower airflow cubic feet per minute (CFM) may be calculated by energizing electric heat and measuring:
Temperature rise between the return air and supply air
temperatures at the indoor coil blower unit,
Measuring voltage supplied to the unit,
Measuring amperage being drawn by the heat unit(s).
Then, apply the measurements taken in following formula
to determine CFM:
CFM =
Amps x Volts x 3.41
1.08 x Temperature rise (F)
Cº T
DROP
– DT = ºF ACTION
53º 19 – 15 = 4 INCREASE THE AIRFLOW
58º 14 – 15 = −1 (WITHIN +3º RANGE) NO CHANGE
62º 10 – 15 = −5 DECREASE THE AIRFLOW
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
TEMPERATURE OF AIR
ENTERING INDOOR COIL ºF
INDOOR COIL
DRY BULB
DRY
BULB
WET BULB
B
T
DROP
19º
A
DRY−BULB
WET−BULB ºF
A
72º
B
64º
C
53º
AIR FLOWAIR FLOW
ALL TEMPERATURES ARE EXPRESSED IN ºF
1. DETERMINE THE DESIRED DT MEASURE ENTERING AIR TEMPERATURE USING DRY BULB (A) AND WET BULB (B). DT IS THE INTERSECTING VALUE
OF A AND B IN THE TABLE (SEE TRIANGLE).
2. FIND TEMPERATURE DROP ACROSS COIL
MEASURE THE COIL’S DRY BULB ENTERING AND LEAVING AIR TEMPERATURES (A AND C). TEMPERA-
TURE DROP FORMULA: (T
DROP
) = A MINUS C.
3. DETERMINE IF FAN NEEDS ADJUSTMENT IF THE DIFFERENCE BETWEEN THE MEASURED T
DROP
AND THE DESIRED DT (T
DROP
–DT) IS WITHIN +3º,
NO ADJUSTMENT IS NEEDED. SEE EXAMPLE BELOW:
4. ADJUST THE FAN SPEED See indoor unit instructions to increase/decrease fan speed.
ASSUME DT = 15 AND A TEMP. = 72º, THESE C TEMPERATURES WOULD NECESSITATE STATED ACTIONS:
AIRFLOW
USE THE FOLLOWING PROCEDURE TO ADJUST FOR OPTIMAL AIR FLOW ACROSS THE INDOOR COIL:
INDOOR COIL
CHANGING AIR FLOW AFFECTS ALL TEMPERATURES; RECHECK
TEMPERATURES TO CONFIRM THAT THE TEMPERATURE DROP AND
DT ARE WITHIN +
3º.
Figure 16. Checking Indoor Airflow over Evaporator Coil using Delta−T Chart
Page 28
Page 28
XP21
Use WEIGH IN method for adding initial refrigerant charge, and then use SUBCOOLING method for for verifying refrigerant charge.
WEIGH IN
LIQUID LINE SET DIAMETER
OUNCES PER 5 FEET (G PER 1.5 M) ADJUST FROM 15 FEET (4.6 M)
LINE SET*
3/8" (9.5 MM)
3 OUNCE PER 5’ (85 G PER 1.5 M)
*IF LINE LENGTH IS GREATER THAN 15 FT. (4.6 M), ADD THIS AMOUNT. IF LINE LENGTH IS LESS THAN 15 FT. (4.6
M), SUBTRACT THIS AMOUNT.
Refrigerant Charge per Line Set Length
NOTE THE ABOVE NAMEPLATE IS FOR ILLUSTRATION PURPOSES ONLY. GO TO ACTUAL NAMEPLATE ON OUTDOOR
UNIT FOR CHARGE INFORMATION.
CHARGING METHOD
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.
CALCULATING SYSTEM CHARGE FOR OUTDOOR UNIT VOID OF CHARGE
IF THE SYSTEM IS VOID OF REFRIGERANT, FIRST, LOCATE AND REPAIR ANY LEAKS AND THEN WEIGH IN THE REFRIGERANT CHARGE INTO THE UNIT.
TO CALCULATE THE TOTAL REFRIGERANT CHARGE:
AMOUNT SPECIFIED
ON NAMEPLATE
ADJUST AMOUNT. FOR VARIATION IN
LINE SET LENGTH LISTED ON LINE
SET LENGTH TABLE BELOW.
ADDITIONAL CHARGE SPECIFIED
PER INDOOR UNIT MATCH−UPS
STARTING ON PAGE 29
TOTAL
CHARGE
+
+
=
Figure 17. Using HFC−410A Weigh In Method
1. CHECK THE AIRFLOW AS ILLUSTRATED IN FIGURE 16 TO BE SURE THE INDOOR AIRFLOW IS AS REQUIRED. (MAKE
ANY AIR FLOW ADJUSTMENTS BEFORE CONTINUING WITH THE FOLLOWING PROCEDURE.)
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 TABLE 8, 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:
USE
COOLING
MODE
USE
HEATING
MODE
60ºF
(15ºC)
SATº
LIQº –
SCº =
SUBCOOLING
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 TABLE 9 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 TABLES 3 THROUGH 7, BEING SURE TO NOTE ANY ADDITIONAL CHARGE FOR LINE
SET AND/OR MATCH−UP.
10. IF SUBCOOLING VALUE IS GREATER THAN SHOWN IN TABLES 3 THROUGH 7 FOR THE APPLICABLE UNIT, REMOVE
REFRIGERANT; IF LESS THAN SHOWN, ADD REFRIGERANT.
11. IF REFRIGERANT IS ADDED OR REMOVED, REPEAT STEPS 5 THROUGH 6 TO VERIFY CHARGE.
12. DISCONNECT GAUGE SET AND RE−INSTALL BOTH THE LIQUID AND SUCTION SERVICE VALVE CAPS.
USING COOLING MODE WHEN THE OUTDOOR AMBIENT TEMPERATURE IS 60°F (15°C) AND ABOVE. TARGET
SUBCOOLING VALUES (SECOND STAGE − HIGH CAPACITY) IN TABLE 8 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 TABLE 8 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.
CHARGING METHOD
Figure 18. Using HFC−410A Subcooling Method High Stage (High Capacity)
Page 29
Page 29
XP21
Air Handler / Indoor Coil Matchups and Targeted Subcooling Values
Listed below are the targeted subcooling and charging values for approved indoor unit air handler / coil matchups.
This information is also listed on the unit charging sticker
located on the access panel. * Indicates amount of charge
required in additional to charge shown on unit nameplate.
Remember to consider line set length differences.
Table 3 XP21−024−230−ALL
Model Number
Target SC Add Charge*
Heat
(+5ºF)
Cool
(+1º)
lb. oz.
CB(X)27UH−024 15 4 0 0
CB(X)27UH−030 22 7 1 10
CBX32M−036 and
CBX32MV−036
22 7 1 10
CBX32M−030 and
CBX32MV−24/30
15 4 0 0
CBX40UHV−024 22 7 1 10
CBX40UHV−030 22 7 1 10
CBX40UHV−036 22 7 1 10
CH23−51 18 4 0 10
CH33−31 18 4 0 10
CH33−42 18 4 0 10
CR33−48 32 4 0 0
CR33−50/60C 14 7 1 10
CX34−31 27 4 0 10
CX34−34/48B 22 5 1 3
CX34−38 25 6 1 7
Table 4 XP21−036−230−ALL
Model Number
Target SC Add Charge*
Heat
(+5ºF)
Cool
(+1º)
lb. oz.
CB(X)27UH−036 17 5 0 0
CB(X)27UH−042 12 5 1 10
CBX32M−036 and
CBX32MV−036
17 5 0 0
CBX32M−048 and
CBX32MV−048
12 5 1 10
CBX40UHV−036 17 5 0 0
CBX40UHV−042 12 5 1 10
CBX40UHV−048 12 5 1 10
CH23−51 19 7 0 0
CH33−43 11 5 0 7
CH33−44/48B 11 5 0 7
CH33−48C 32 7 0 7
CH33−50/60C 12 7 1 6
CR33−48 32 4 0 7
CR33−50/60C 11 4 1 8
CX34−38 15 5 0 7
CX34−44/48B 19 4 0 10
CX34−49 10 10 1 10
CX34−50/60C 11 5 0 7
Table 5 XP21−048−230−ALL
Model Number
Target SC Add Charge*
Heat
(+5ºF)
Cool
(+1º)
lb. oz.
CB(X)27UH−048 24 4 1 0
CB(X)27UH−060 14 4 1 6
CBX32M−048 and
CBX32MV−048
24 4 1 0
CBX32M−060 and
CBX32MV−060
21 4 1 14
CBX32MV−068 14 4 1 0
CBX40UHV−048 24 4 1 0
CBX40UHV−060 21 4 1 14
CH23−68 14 4 1 6
CH33−49C 21 4 1 14
CH33−50/60C 21 4 1 14
CH33−62D 20 4 1 7
CR33−50/60 32 4 0 0
CR33−60D 32 4 0 0
CX34−49 21 5 0 10
CX34−62C 11 4 1 5
CX34−62D 11 4 1 5
Table 6. XP21−060−230−01 Only
Model Number
Target SC Add Charge*
Heat
(+5ºF)
Cool
(+1º)
lb. oz.
CB(X)27UH−060 15 4 1 2
CBX32M−060 and
CBX32MV−060
12 4 1 10
CBX32MV−068 14 4 1 0
CBX40UHV−060 12 4 1 10
CH23−68 15 4 1 6
CH33−49C 16 4 1 0
CH33−50/60C 16 4 1 0
CH33−62D 13 5 1 3
CR33−50/60 23 5 0 0
CR33−60D 23 5 0 0
CX34−49 16 4 1 0
CX34−62C 13 5 1 3
CX34−62D 13 5 1 3
Table 7 XP21−060−230−02 and Later
Model Number
Target SC Add Charge*
Heat
(+5ºF)
Cool
(+1º)
lb. oz.
CB(X)27UH−060 7 6 0 10
CBX32M−060 and
CBX32MV−060
10 4 0 0
CBX32MV−068 9 4 0 10
CBX40UHV−060 10 4 0 0
CH23−68 10 4 0 10
CH33−49C 7 5 0 0
CH33−50/60C 7 5 0 0
CH33−62D 9 4 0 7
CR33−50/60 22 5 0 4
CR33−60D 22 5 0 4
CX34−49 10 5 0 4
CX34−62C 7 5 0 0
CX34−62D 7 5 0 0
Page 30
Page 30
XP21
Operating and Temperature Pressures (All Builds)
Minor variations in these pressures may be expected due to differences in installations. Significant differences could mean
that the system is not properly charged or that a problem exists with some component in the system.
Table 8. Normal Operating Pressure − Liquid +10 and Vapor +5 PSIG*
5F (5C)**
XP21−024−230−ALL XP21−036−230−ALL XP21−048−230−ALL XP21−060−230−01 Only
XP21−060−230−02 and
Later
Liq Vap Liq Va p Liq Vap Liq Vap Liq Va p
Low Stage Heating Operation
40 (4) 319 104 307 99 367 92 371 93 322 96
50 (10) 345 122 331 117 385 113 402 111 352 115
60 (16) 380 144 350 137 415 130 428 128 371 132
Low Stage Cooling Operation
65 (18) 224 149 224 145 229 142 235 138 227 139
70 (21) 241 149 241 147 247 142 253 139 244 141
75 (24) 260 150 261 148 266 143 273 140 263 142
80 (27) 281 150 282 149 288 144 294 141 284 143
85 (29) 303 151 303 150 311 145 317 143 305 144
90 (32) 325 152 326 151 334 146 340 144 328 146
95 (35) 348 154 350 152 358 147 364 145 352 147
100 (38) 372 155 374 153 383 149 390 146 376 148
105 (41) 397 156 400 154 410 150 417 147 402 150
110 (43) 425 159 427 155 438 151 445 149 429 151
115 (46) 453 155 456 157 468 152 476 150 458 153
High Stage Heating Operation
20 (−7) 312 67 293 62 326 63 340 59 305 62
30 (−1) 351 82 309 76 353 76 353 68 320 72
40 (4) 364 98 322 90 375 93 373 89 347 90
50 (10) 390 11 7 341 109 405 11 0 404 104 366 105
60 (16) 420 140 357 129 437 127 429 121 387 120
High Stage Cooling Operation
65 (18) 231 144 237 140 240 138 247 131 236 134
70 (21) 250 145 254 141 259 139 268 133 252 135
75 (24) 270 146 275 142 279 140 286 134 272 136
80 (27) 291 147 294 143 299 140 308 137 294 137
85 (29) 312 148 315 146 323 142 327 143 316 139
90 (32) 336 149 338 147 346 143 350 144 339 140
95 (35) 360 150 363 148 371 144 374 146 364 141
100 (38) 387 151 389 150 397 145 401 147 389 142
105 (41) 411 152 415 151 423 146 428 148 416 144
110 (43) 438 153 443 152 451 147 458 149 445 145
115 (46) 467 154 473 153 481 149 489 151 475 146
Table 9. HFC−410A Temperature (°F) − Pressure (Psig)
°F Psig °F Psig °F Psig °F Psig °F Psig °F Psig °F Psig °F Psig
32 100.8 48 137.1 63 178.5 79 231.6 94 290.8 110 365.0
125 445.9
141 545.6
33 102.9 49 139.6 64 181.6 80 235.3 95 295.1 111 370.0 126 451.8 142 552.3
34 105.0 50 142.2 65 184.3 81 239.0 96 299.4 112 375.1 127 457.6 143 559.1
35 107.1 51 144.8 66 187.7 82 242.7 97 303.8 113 380.2 128 463.5 144 565.9
36 109.2 52 147.4 67 190.9 83 246.5 98 308.2 114 385.4 129 469.5 145 572.8
37 111.4 53 150.1 68 194.1 84 250.3 99 312.7 115 390.7 130 475.6 146 579.8
38 113.6 54 152.8 69 197.3 85 254.1 100 317.2 11 6 396.0 131 481.6 147 586.8
39 115.8 55 155.5 70 200.6 86 258.0 101 321.8 11 7 401.3 132 487.8 148 593.8
40 118.0 56 158.2 71 203.9 87 262.0 102 326.4 11 8 406.7 133 494.0 149 601.0
41 120.3 57 161.0 72 207.2 88 266.0 103 331.0 11 9 412.2 134 500.2 150 608.1
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
Page 31
Page 31
XP21
III. SYSTEM OPERATION AND SERVICE
OUTDOOR CONTROL − PART NUMBER 101796−XX
Heat Pump Control (A175) Jumpers and Terminals
55
50
DEGREE
TARGET
45
DEGREE
TARGET
*40
DEGREE
TARGET
55
50
45
40
55
50
45
40
55
50
45
40
55
50
45
40
DEGREE
TARGET
100
90
DEGREE
TARGET
70
DEGREE
TARGET
50
DEGREE
TARGET
100
90
70
50
DEGREE
TARGET
DEFROST TERMINATION TEMPERATU
R
100
90
70
50
100
90
70
50
100
90
70
50
30
0
30
SECOND DELAY
SECOND DELAY*
0
LED ALERT CODES
LED ALERT CODES
INDICATES RS−BUS DATA
COMMUNICATION IS ACTIVE.
(COMMUNICATION MODE
ONLY)
COMMUNICATING
STATUS INDICATOR
TABLE 10 ON PAGE 32 PROVIDES ADDITIONAL INFORMATION
CONCERNING JUMPERS, LINKS, AND CONNECTIONS FOR THE HEAT PUMP
CONTROL.
E37
E47
DS12
E48
E34
DS11 and DS14
DS13 and DS15
CUT FOR HUMIDITROL APPLICATION
(TWO−STAGE UNITS ONLY)
W1
JUMPER
NO
INSTALLED
E33
USED FOR CONFIGURING
CONTROL OR CLEARING
LOCKOUTS (SEE FIGURE
25 FOR DESCRIPTION OF
VARIOUS FUNCTIONS)
HEAT PUMP CONTROL TWO STAGE
NOTE SETTING IS ONLY
AVAILABLE ON OUTDOOR
CONTROL PART NUMBERS
101796−01 THROUGH −03
COMPRESSOR SHIFT DELAY
THE OUTDOOR CONTROL
PART NUMBER IDENTIFICATION
IS LOCATED HERE.
NOTE ON OUTDOOR CONTROL
PART NUMBERS 101796−04 AND
LATER FAN CYCLING IS ON WHEN
JUMPER IS SET TO 0 SECOND DELAY.
FOR MORE INFORMATION ON THE
FAN CYCLING FEATURE SEE PAGE 62.
SECOND−STAGE
LOCK−IN TEMPERATURE
2ND STAGE
LOCK−IN
DISABLED
55
50
45
40
(FACTORY
DEFAULT)
(FACTORY
DEFAULT)
(FACTORY
DEFAULT)
100
90
70
50
OR WHEN
JUMPER
NOT
INSTALLED
Y2 SOLENOID COIL
(SEE TABLE 10 FOR
FURTHER DETAILS)
Figure 19. Heat Pump Control Connections, Jumper Settings and LED Locations
Page 32
Page 32
XP21
Table 10. Heat Pump Control (A175) Jumper and Terminal Descriptions
Control ID Label Description
E12 PSC Fan 240 VAC output connection for outdoor fan.
E16 PSC Fan 240 VAC input connection for outdoor fan.
E18
W 24VAC output for defrost auxiliary heat output.
L Thermostat service light connection.
Y2 24VAC thermostat input/output for second stage operation of the unit.
Y1 24VAC thermostat input for first stage operation of the unit.
O 24VAC thermostat input for reversing valve operation
DS Humiditrol Input
C 24VAC system common
i− Input/Output − RSBus data low. Used in communicating mode only with compatible indoor thermostat.
i+ Input/Output − RSBus data high. Used in communicating mode only with compatible indoor thermostat.
R 24VAC system power input
E19 and E20 O OUT 24 VAC output connection for reversing valve.
E21 and E22 LO−PS Connection for low−pressure switch (2.4 milliamps @ 18VAC)
E31 and E32 Y1 OUT 24 VAC common output, switched for enabling compressor contactor.
E24 and E25 HS−PS Connection for high−pressure switch.
E26 FAN 1
First Stage and second stage basic and precision dehumidification ECM fan motor 24VDC output connection
1.
E27 FAN 2 Second stage basic and precision dehumidification ECM fan motor 24VDC output connection 2.
E28 FAN C ECM common connection for ECM fan.
E30
Six position square pin header. P4 provides connections for the temperature sensors.
DIS (YELLOW)
PINS 5 and 6
DIS 5 Discharge line temperature sensor supply.
DIS 6 Discharge line temperature sensor return.
Range is 35ºF to 310ºF. Sensor is clipped on a 1/2" copper tube.
AMB (BLACK)
Pins 3 and 4
AMB 3 Outdoor ambient temperature sensor supply.
AMB 4 Outdoor ambient temperature return.
Range is 40ºF to +140ºF
COIL (BROWN)
Pins 1 and 2
COIL 1 Outdoor coil temperature sensor supply.
COIL 2 Outdoor coil temperature sensor return
Range is 40ºF to 140ºF. Sensor is clipped on a 5/16" copper return bend.
E33 Field Test
This jumper allows service personnel to defeat the timed off control, initiate or terminate a defrost and field
programming of unit capacity feature and clears lockouts.
E34 Y2 Solenoid
Keyed plug header used for second−stage compressor output. Sequence for Y2 solenoid coil operations:
Five (5) second delay after Y2 is ON.
Two (2) seconds full 24VDC.
Pulsing voltage to keep solenoid engage
E37 Comp Shift Delay
Two position square pin header. When jumper is installed, a 30−second compressor shift delay is
implemented. It de−energizes the compressor contactor, second−stage solenoid (if on) and the ECM fan
outputs. After the timer expires, the compressor contactor and ECM fan outputs are energized. If no jumper
is installed, it changes the reversing valve direction and de−energizing the outputs immediately. On outdoor
control part number 101796−04 and later, removing jumper also enables the fan cycling option.
E47
50*
70
90
100
Seven position square pin header. E47 provides selection of the defrost terminate temperature based on the
position of the selection jumper. The defrost termination temperature is measured by the RT21
coil tempera-
ture sensor. The jumper termination pin is factory set at 50°F (10°C). If the temperature jumper is not installed,
the default termination temperature is 90°F (32°C).
E48
55
50
45
40 *
(This option is only available on outdoor control part numbers 101796−01 through −03) Five position
square pin header. If the first−stage compressor output is active in heating mode and the outdoor ambient
temperature is below the selected compressor lock−in temperature, the second−stage compressor solenoid
outputs will be energized without the Y2 input. If the jumper is not present on E48, the default lock−in
temperature of 40ºF will be used.
W1 Short DS To R
Cut for Humiditrol (EDA) application. This sets the outdoor fan speed to predefined speed. See table 17 for
set speed based on unit capacity size. Use only in two−stage units.
* Factory default setting
Page 33
Page 33
XP21
System Status, Fault and Lockout LED
Codes
LED codes are displayed via various LEDs located on the
heat pump control (A175). See figure 19 for location of heat
pump control LEDs.
DS11 AND DS14 SYSTEM STATUS, FAULT AND
LOCKOUT LED CODES
DS11 (Green) and DS14 (Red) LEDs indicate non−communicating mode diagnostics conditions that are listed in table
11.
These LEDs display the most common fault conditions in
the system. When an abnormal condition is detected, this
function communicates the specific condition through LED
alert codes. The function is capable of detecting both mechanical and electrical system problems.
DS15 AND DS13 COMPRESSOR FAULT AND
LOCKOUT LED CODES
DS15 (yellow) and DS13 (red) LEDs indicate non−communicating mode diagnostics conditions that are listed in table
11.
These LEDs display fault conditions in system cooling or
heating modes, dehumidification mode, anti−short cycle
lockout, high and low pressures, discharge line temperature, outdoor temperature, and discharge sensor failures.
IMPORTANT
DS15 and DS13 compressor LED fault and lockout
codes do not provide safety protection. The is a
monitoring function only and cannot control or shut down
other devices.
RESETTING FAULT AND LOCKOUT LED CODES
All LED fault and lockout codes can be reset manually or
automatically.
1. Manual Reset
Manual reset can be achieve by one of the following
methods:
Disconnecting R wire from the heat pump control’s
R terminal.
Turning the indoor unit off an on again
After power up, existing code will display for 60 seconds and then clear.
2. Automatic Reset
After a fault or lockout is detected, the heat pump control continues to monitor the compressor and outdoor
unit. When/if conditions return to normal, the fault or
lockout LED code is turned off automatically.
Table 11. System Status, Fault and Lockout LED Codes and Related icomfortt Thermostat Alert Codes
(Outdoor Unit Codes Only)
System fault and lockout LED (DS11 / DS14) alarm codes takes precedence over system status LED codes (cooling, heating stages or
defrost/dehumidification). Only the latest active LED fault or lockout alarm code if present will be displayed. If no fault or lockout codes are active, then
system status LEDs are routinely displayed. See notes 1 and 2 in table below for duration of fast / slow flashes and pause.
Heat Pump Control
LEDs
icomfortt
Thermostat
Display
Condition Possible Cause(s) Solution
DS11
Green
DS14 Red
SYSTEM STATUS
Off Off
Not
applicable
Power problem
1. No power (24V) to
heat pump control
terminal’s R and C or
heat pump control
failure.
2. Heat pump control
failure.
1
Check control transformer power (24V).
2
If power is available to control and LED(s) do not
light, replace the heat pump control.
Simultaneous slow flash
Not
applicable
Normal operation Unit operating normally or in standby mode.
Alternating slow flash
Not
applicable
5−minute
anti−short cycle
delay
Initial power up, safety trip,
end of room thermostat demand.
None required (Jumper FIELD TEST (E33) pins to
override)
On On
Not
applicable
Heat pump
control failure
Indicates that heat pump control has an internal component failure. Cycle 24 volt
power to heat pump control. If code does not clear, replace the heat pump control.
Page 34
Page 34
XP21
System fault and lockout LED (DS11 / DS14) alarm codes takes precedence over system status LED codes (cooling, heating stages or
defrost/dehumidification). Only the latest active LED fault or lockout alarm code if present will be displayed. If no fault or lockout codes are active, then
system status LEDs are routinely displayed. See notes 1 and 2 in table below for duration of fast / slow flashes and pause.
Heat Pump Control
LEDs
SolutionPossible Cause(s)Condition
icomfortt
Thermostat
Display
DS11
Green
SolutionPossible Cause(s)Condition
icomfortt
Thermostat
Display
DS14 Red
DS11
Green
SolutionPossible Cause(s)Condition
icomfortt
Thermostat
Display
DS14 Red
Off
1 fast flash
then pause
Not
applicable
First−stage
compressor
heating
These are codes that show status of operation whether the system is operating in either
in first or second stage heating or cooling operation, defrost or in the dehumidification
modes.
Off
2 fast
flashes
then pause
Not
applicable
Second−stage
compressor
heating
On
2 fast
flashes
then pause
Not
applicable
Defrost
1 fast flash
then pause
Off
Not
applicable
First−stage
compressor
cooling
2 fast
flashes
then pause
Off
Not
applicable
Second−stage
compressor
cooling
2 fast
flashes
then pause
On
Not
applicable
Dehumidification
mode
ALERT STATUS
None
Moderate
Alert Code
105
Device
communication
failure
Equipment is unable to communicate. Indicates numerous message errors. In most
cases errors are related 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.
None
Moderate
Alert Code
120
Unresponsive
device
Usually caused by delay in outdoor unit responding to indoor unit poling.
Recycle power. Check all wiring connections. Cleared after unresponsive
device responds to any inquiry.
None
Critical Alert
Code 124
Active subnet
controller missing
for 180 seconds
Equipment lost communication with the thermostat. Check four wiring connections,
ohm wires and cycle power at the thermostat. Alert stops all services and waits for
heartbeat message from thermostat (subnet controller). Cleared after valid thermostat
(subnet controller) message is received.
None
Critical Alert
Code 125
Hardware Failure
Hardware problem on the control. Cycle power on control. Replace if problem
prevents service and is persistent. Cleared 300 seconds after fault recovered.
None
Moderate /
Critical Alert
Code 126
Internal control
communication
failure
Internal communication on heat pump control. Alert will clear 300 seconds after fault
has recovered.
None
Critical Alert
Code 131
Corrupted control
parameters
Reconfigure the system. Replace control if heating or cooling is not available. Only
applicable in the communicating mode, not in start up. Exit from Commissioning and
Execute ´Set Factory Default mode´. Control will still operate on default parameter
settings.
Simultaneous fast
flashes
Moderate /
Critical Alert
Code 180
Ambient sensor
problem
If sensor detects an open, shorted or out−of−temperature range. heat pump control will
revert to time/temperature defrost operation. System will still heat or cool.
None
Moderate
Alert Code
409
Low 24VAC. Sec-
ondary voltage is
low.
Secondary voltage is below 18VAC. After 10 minutes, operation is discontinued.
Clears the code after voltage is higher than 20 VAC for 2 seconds or after power reset.
Off
Slow flash
Moderate
Alert Code
410
Low pressure
fault
Unit pressures below the lower limit. System is shut down. Clears after pressure
switch closes.
Off On
Critical Alert
Code 411
Low pressure
switch lockout
Open low pressure switch error count reached 5 strikes. Check system charge using
approach and subcooling temperatures. Reset by putting outdoor unit control in test
mode or resetting low voltage power.
Page 35
Page 35
XP21
System fault and lockout LED (DS11 / DS14) alarm codes takes precedence over system status LED codes (cooling, heating stages or
defrost/dehumidification). Only the latest active LED fault or lockout alarm code if present will be displayed. If no fault or lockout codes are active, then
system status LEDs are routinely displayed. See notes 1 and 2 in table below for duration of fast / slow flashes and pause.
Heat Pump Control
LEDs
SolutionPossible Cause(s)Condition
icomfortt
Thermostat
Display
DS11
Green
SolutionPossible Cause(s)Condition
icomfortt
Thermostat
Display
DS14 Red
DS11
Green
SolutionPossible Cause(s)Condition
icomfortt
Thermostat
Display
DS14 Red
Slow flash Off
Moderate
Alert Code
412
High pressure
fault
Unit pressure is above the upper limit. System is shut down. Check system operating
pressures and compare to unit charging charts. Clears when pressure switch closes.
On Off
Critical Alert
Code 413
High pressure
switch lockout
Open high pressure switch error count reached 5 strikes. Check system charge using
approach and subcooling temperatures. Check outdoor fan operation. Check for dirt
or debris blocking air flow to outdoor unit. Reset by putting outdoor unit control in test
mode or resetting low voltage power.
Slow flash On
Moderate
Alert Code
414
High Discharge
line temperature
fault
Discharge line temperature is > 279ºF. Check system operating pressures and
compare to unit charging charts in installation manual. Clears after discharge
temperature is < 225ºF.
Fast flash On
Critical Alert
Code 415
High Discharge
Line Temperature
Strikes Lockout
Discharge line high temperature error count reached 5 strikes. Check system charge
using approach and subcooling temperatures. Reset by putting outdoor board in test
mode or resetting low voltage power.
Fast flash On
Critical Alert
Code 416
Outdoor Coil
Sensor Faulty
Sensor being detected open or shorted, or temperature is out of sensor range.
Outdoor unit control will not perform demand or time/temperature defrost operation.
(System will still heat or cool.) Clears when outdoor unit control detects proper sensor
readings.
Off Fast flash
Moderate /
Critical Alert
Code 417
Discharge sensor
fault
Outdoor unit control detects open or shorted sensor, or temperature that is out of
sensor range. Critical Alert after 10 minutes. Reset by replacing sensor. This fault is
detected by allowing the unit to run for 90 seconds before checking sensor
resistance. If the sensor resistance is not within range after 90 seconds, the board will
count one fault. After 5 faults, the board will lock out. Check for proper sensor reading
and attachment to line. Replace if out−of−spec.
3 fast
flashes
then pause
Off
Moderate /
Critical Alert
Code 418
W output
hardware fault
When auxiliary heat output is detected as active. Fault in the heat pump control. Replace heat pump control. See figure 47 for further details.
3 fast
flashes
then pause
On
Moderate /
Critical Alert
Code 419
W output
hardware fault
lockout
If heat pump control recognizes five output hardware fault events during a single cooling demand, the heat pump control will initiate a lockout. See figure 47 for further
details.
Off
3 fast
flashes
then pause
Critical Alert
Code 421
W external
miswire fault
When auxiliary heat output is detected as active after compressor has been de−energized. See figure 47 for further details.
Simultaneous fast
flashes then pause
None
Second−stage
heat lock−in
If the unit is in non−communicating mode and it goes to second stage due to ambient
temperature being below second stage lock−in setting (E48).
Fast simultaneous flashing of DS11,
DS13, DS14 and DS15
OEM mode Factory test mode.
1. Pause duration is two (2) seconds.
2. Fast flash duration is 1/2 second. Slow flash duration is one (1) second.
Page 36
Page 36
XP21
Table 12. Compressor Fault and Alarm LED Codes and Related icomfortt Thermostat Alert Codes
NOTE See notes 1 and 2 in table below for duration of fast / slow flashes and pause.
Heat Pump Control
LEDs
icomfortt
Thermostat
Display
Condition
Possible
Cause(s)
Solution
Clearing Status
DS15
Yellow
DS13
Red
Off On
Moderate/
Critical
3
Alert
Code 400
Compressor
internal
overload trip
Thermostat
demand signal
Y1 is present, but
compressor not
running
1
Compressor protector is open.
Check for high head pressure
Check compressor supply voltage
2
Outdoor unit power disconnect is open.
3
Compressor circuit breaker or fuse(s) is open.
4
Broken wire or connector is not making contact.
5
Low or high pressure switch open if present in
the system.
6
Compressor contactor has failed to close.
Clears the error
after current is
sensed in the
run and start
winding for two
seconds, service removed or
power reset.
1 flash
then
pause
Off
Critical Alert
Code 401 on
outdoor
controls
101796−01
through −04.
Moderate
Alert Code
401 on
101796−04
and later
Long run
time.
Compressor is
running extremely long run
cycles.
1
Low refrigerant charge.
2
Evaporator blower is not running.
Check blower relay coil and contacts
Check blower motor capacitor
Check blower motor for failure or blockage
Check evaporator blower wiring and connec-
tors
Check indoor blower control
Check thermostat wiring for open circuit
3
Evaporator coil is frozen.
Check for low suction pressure
Check for excessively low thermostat setting
Check evaporator airflow (coil blockages or re-
turn air filter)
Check ductwork or registers for blockage.
4
Faulty metering device.
Check TXV bulb installation (size, location and
contact)
Check if TXV/fixed orifice is stuck closed or de-
fective
5
Condenser coil is dirty
.
6
Liquid line restriction (filter drier blocked if present)
.
7
Thermostat is malfunctioning
.
Check thermostat sub−base or wiring for short
circuit
Check thermostat installation (location and
level)
Clears the error
after 30 consecutive normal run
cycles, or after
power reset.
2 flashes
then
pause
Off
Critical Alert
Code 402
System
pressure trip
Indicates the
compressor
protector is open
or missing supply
power to the
compressor.
1
High head pressure.
Check high pressure switch if present in sys-
tem
Check if system is overcharged with refriger-
ant
Check for non−condensable in system
2
Condenser coil poor air circulation (dirty,
blocked, damaged).
3
Condenser fan is not running.
Check fan capacitor
Check fan wiring and connectors
Check fan motor for failure or blockage
4
Return air duct has substantial leakage.
Clears after four
consecutive
normal compressor run
cycles, or after
power reset.
3 flashes
then
pause
Off
Moderate
Alert Code
403
Short cycling
Compressor is
running less than
three minutes.
1
Thermostat demand signal is intermittent.
2
Time delay relay or heat pump control is defective.
3
If high pressure switch is present, see flash code
2 information.
Clears after four
consecutive
normal compressor run
cycles, or after
power reset.
Page 37
Page 37
XP21
Heat Pump Control
LEDs
Clearing Status
Solution
Possible
Cause(s)
Condition
icomfortt
Thermostat
Display
DS15
Yellow
Clearing Status
Solution
Possible
Cause(s)
Condition
icomfortt
Thermostat
Display
DS13
Red
4 flashes
then
pause
Off
Critical Alert
Code 404
Locked rotor
Compressor has
a locked out due
to run capacitor
short, bearings
are seized,
excessive liquid
refrigerant.
1
Run capacitor has failed.
2
Low line voltage (contact utility if voltage at
disconnect is low).
Check wiring connections
3
Excessive liquid refrigerant in the compressor.
4
Compressor bearings are seized.
Clears after
power reset or
four normal
compressor
cycles.
5 flashes
then
pause
Off
Critical Alert
Code 405
Open circuit
Compressor has
an open circuit
due to power disconnection, fuse
is open or other
similar conditions.
1
Outdoor unit power disconnect is open.
2
Unit circuit breaker or fuse(s) is open.
3
Unit contactor has failed to close.
Check compressor contactor wiring and
connectors
Check for compressor contactor failure
(burned, pitted or open)
Check wiring and connectors between supply
and compressor
Check for low pilot voltage at compressor
contactor coil
4
High pressure switch is open and requires
manual reset.
5
Open circuit in compressor supply wiring or
connections.
6
Unusually long compressor protector reset time
due to extreme ambient temperature.
7
Compressor windings are damaged.
Check compressor motor winding resistance
Clears after one
normal compressor run
cycle or power
reset.
6 flashes
then
pause
Off
Critical Alert
Code 406
Open start
circuit
Current not
sensed by Start
transformer.
1
Run capacitor has failed.
2
Open circuit in compressor start wiring or
connections.
Check wiring and connectors between supply
and the compressor S terminal
3
Compressor start winding is damaged.
Check compressor motor winding resistance
Clears when
amperage is detected in RUN
and START
sensors, or after
power reset.
7 flashes
then
pause
Off
Critical Alert
Code 407
Open run
circuit
Current not
sensed by run
transformer.
1
Open circuit in compressor start wiring or
connections.
Check wiring and connectors between supply
and the compressor R terminal
2
Compressor start winding is damaged.
Check compressor motor winding resistance
Clears when
amperage is detected in RUN
and START
sensors, or after
power reset.
8 flashes
then
pause
Off
Critical Alert
Code 408
Welded
contactor
Compressor
always runs
1
Compressor contactor failed to open.
2
Thermostat demand signal not connected to
module.
Clears after one
normal compressor run
cycle or after
power reset.
9 flashes
then
pause
Off
Moderate/
Critical Alert
3
Code 409
Secondary
low voltage
24VAC is below
18VAC.
1
Control circuit transformer is overloaded.
2
Low line voltage (contact utility if voltage at
disconnect is low).
Check wiring connections
Clears after
voltage is higher than 20VAC
for two seconds, or after
power reset.
Fast simultaneous flashing of DS11,
DS13, DS14 and DS15
OEM Mode Factory test mode.
1. Pause duration is two (2) seconds.
2. Fast flash duration is 1/2 second. Slow flash duration is one (1) second.
3. Initially a moderate status is displayed and is escalated to critical if alarm exists for more than 10 minutes.
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XP21
Component Field Configuration and
Troubleshooting
FAN MOTOR CONTROL (A177)
This section provides procedures for testing the fan control.
FAN MOTOR CONTROL LED CODES, JUMPER SETTINGS AND SEQUENCE OF OPERATION
During start up, the LED:
1. Display error conditions (see table 15), if present
2. If no errors are detected, then the LED code indicating
stage operation (see table 16) will display the applicable code and then a long pause.
3. The fan motor speed / revolutions per minute (RPM) indicator is displayed next (see table 17).
4. After the RPM indicator is displayed, there is a short
pause. The sequence repeats if a thermostat demand
is still present. See figure 20 for LED sequence. See
table 16 for description of flash and pause durations.
FAN MOTOR CONTROL TROUBLESHOOTING
Use the following subsections to verify and test the fan motor control (A177).
Verifying Jumper Settings (J2)
The unit is shipped from the factory with the default fan motor speed setting (in RPMs) required for each specific
model. Use table 17 to verify that jumpers are set correctly
for the specific size unit.
Verifying LED Status Codes
During start up, the fan motor control LED will display any error conditions. If error conditions exist
then no other codes will display. If no error conditions are present, then the stage status and and RPM
indicator are displayed. Two−stage units have various
fan motor speed operations available (see table 17).
Verifying Correct DC Output Voltage (J2)
The following three methods can be used to determine
whether the fan motor (B4) is operating at the correct
RPMs based on unit size.
1. Use the information provided in table 17 to verify that
all four jumper terminals are set correctly for the specific unit.
2. Verify that the fan motor speed / RPM indicator is displaying the correct flash sequence for the specific unit
(see table table 17).
3. Test DC voltage output on the fan motor control’s J2
terminals (see figure 21) while under full load. The actual voltage tested should match the voltage listed in
table 17 for the specific unit.
4. If no voltage is detected at the J2 terminals, verify there
is a Y1 demand at the thermostat.
If there is a demand, proceed to the next section for further
testing.
VERIFYING CORRECT INPUT VOLTAGE (ECM/Y1,
ECM/Y2, ECM C AND EXT ECM/R)
Use a voltmeter to check voltages on the following fan motor control inputs, using either table 13. Voltage will only be
present during a thermostat demand. See figure 22 for test
example.
If correct voltages are detected at the applicable inputs during a demand, and no voltage is present at the J2 terminals,
then the fan motor control (A177) should be replaced.
Table 13. Fan Motor Control Voltage Inputs
Input
Thermostat
Demand
Voltage
Present
ECM/Y1 and ECM C
(Low Stage)
YES
Between
24VDC and 32
VDC
NO NONE
ECM/Y1 − ECM/Y2 and
ECM C
(High Stage)
YES
Between
24VDC and 32
VDC at each
input
NO
NONE at each
input
ECM/Y2 and ECM C
(EDA Operation)
YES
Between
24VDC and 32
VDC
NO NONE
EXT ECM/R and ECM C
YES 24VAC
NO NONE
Page 39
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XP21
Table 14. Fan Motor Control Flash and Pause Durations
Flash or Pause State Duration
Flash Flash Three flashes per second
Slow Flash One flash per second
Short Pause Two seconds of OFF time.
Long Pause Five seconds of OFF time.
Table 15. Fan Motor Control Error/Fault LED Codes
Unit Status Motor Control LED Possible Cause
Mismatched RPM Fast Flash with no pause Internal feedback, PWM does not match target.
CRC Failure Constant ON. Microcontroller CRC failure.
Table 16. Fan Motor Control Stage Operation LED Indicator Codes
Unit Status Unit Status Motor Control LED
Two Stage Operation
Low Stage ECM1/Y1 ONLY One slow flash, then short pause.
High Stage ECM1/Y1 and ECM2/Y2 Two slow flash, then short pause.
EDA Operation ECM2/Y2 ONLY Three slow flash, then short pause.
Table 17. Multi−Stage Fan Motor Control RPM Jumper Settings, LED RPM Indicator and P2 DC
Voltage Outputs
Application
CFM Profile Pin Select
Low Stage ECM1/Y1
Only
High Stage ECM1/Y1
and ECM2/Y2
EDA Operation
ECM2/Y2 Only
4 3 2 1 RPM
LED
Code
DC
Volt
RPM
LED
Code
DC
Volt
RPM
LED
Code
DC
Volt
XP21−024 ON ON OFF ON 425 6 13.6 500 7 16.0 200 3 6.3
XP21−036 ON OFF ON ON 525 7 16.8 600 8 19.2 225 3 7.0
XP21−048 ON OFF OFF ON 600 8 19.2 675 9 21.6 225 3 7.0
XP21−060 ON OFF OFF OFF 625 8 20.0 700 10 22.5 225 3 7.0
* LED Code indicates Fan Motor Control LED flash sequence. For example, LED Code 9 indicates 9 slow flashes and pause.
Page 40
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XP21
DEMAND
MISMATCHED
RPM
DEFAULT
FAN MOTOR
SPEED USED
LED CONTINUOUS FAST
FLASH
REPLACE FAN MOTOR
CONTROL BOARD
CRC
FAILURE
DEFAULT FAN
MOTOR
SPEED USED
LED CONSTANT ON
ONE STAGE
(LOW)
ECM1/Y1
ONLY
LED STAGE INDICATOR:
ONE SLOW FLASH AND
ONE SHORT PAUSE
LED RPM INDICATOR:
EXAMPLE: (2−TON) – 5
SLOW FLASHES AND
LONG PAUSE
TWO STAGE
(HIGH)
LED STAGE INDICATOR:
TWO SLOW FLASHES
AND ONE SHORT PAUSE
LED RPM INDICATOR:
EXAMPLE: (2−TON) – 5
SLOW FLASHES AND
LONG PAUSE
EDA
OPERATION
ECM2/Y2
ONLY
LED STAGE INDICATOR:
THREE SLOW FLASHES
AND ONE SHORT PAUSE
LED RPM INDICATOR:
EXAMPLE: (2−TON – 3
SLOW FLASHES AND
LONG PAUSE
DEMAND
ENDED
NO
DEMAND
ENDED
NO
DEMAND
ENDED
NO
YES
YES
YES
FAN MOTOR
RPM SET PER
JUMPER
SETTINGS
ECM1/Y1
ONLY AND
EMC2/Y2
FAN MOTOR
RPM SET PER
JUMPER
SETTINGS
FAN MOTOR
RPM SET PER
JUMPER
SETTINGS
REPLACE FAN MOTOR
CONTROL BOARD
BEGINS
Figure 20. Fan Motor Control (A177) One/Two Stage and EDA LED Sequence of Operation
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XP21
HEAT PUMP
CONTROL (A175)
CONTROL BOX
FAN MOTOR CONTROL (A177)
PULSE−WIDTH MODULATION (PWM)
JUMPER
OFF
JUMPER
ON
J2
LED
CFM Profile Pin Select
VERIFY DC VOLTAGE OUTPUT USING FAN PWM OUT AND
COM TERMINALS. SEE TABLE 17 FOR OPTIMAL DC
VOLTAGE BASED ON CFM PROFILE USED.
COM
FAN PWM OUT
FAN PWM OUT
PARK
COM
J2
GREEN
RED
BROWN
RED
BLACK
RED
RED
GREEN
FAN MOTOR
CONTROL
YELLOW
BLACK
YELLOW
BLUE
SEE TABLE 17 FOR CFM PROFILE
SELECTION OPTIONS.
YELLOW
YELLOW
YELLOW
HIGH PRESSURE SWITCH (S4)
YELLOW
B4 FAN
MOTOR
HEAT PUMP CONTROL
Figure 21. Fan Motor Control, Wiring, Jumper Settings, Testing and LED Location
Page 42
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XP21
HEAT PUMP
CONTROL (A175)
CONTROL BOX
FAN MOTOR CONTROL (A177)
PULSE−WIDTH MODULATION (PWM)
ONE YELLOW WIRE FROM PS (E24) TERMINAL ON HEAT PUMP
CONTROL. AND SECOND YELLOW WIRES ON PIGGYBACK
TERMINALS GOES TO S4 HIGH PRESSURE SWITCH.
GREEN
RED
BROWN
RED
BLACK
RED
RED
GREEN
FAN MOTOR
CONTROL
YELLOW
BLACK
YELLOW
BLUE
SEE TABLE 17 FOR CFM PROFILE
SELECTION OPTIONS.
BLACK WIRE
YELLOW WIRE
VAC
VDC
24
EXT PWR/R (24VAC INPUT
DURING DEMAND ONLY)
INPUT VOLTAGES DURING DEMAND
ECM/Y1 ONLY − 24VDC
BOTH ECM/Y1 AND ECM/Y2 − 24VDC AT EACH INPUT
ECM/Y2 ONLY − 24VDC
BLUE WIRE
YELLOW
YELLOW
YELLOW
S4 HIGH PRESSURE SWITCH
YELLOW
HEAT PUMP CONTROL
B4 FAN
MOTOR
Figure 22. Testing for External Power to Fan Motor Control (A177)
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XP21
Fan Motor Test Procedure
A simple test can be used to test the fan motor operation. A fully charged 9V battery will be required for this procedure.
J2
FAN PWM OUT
PARK
COM
BLACK LEAD
BROWN LEAD
BROWN LEAD
BLACK LEAD
REMOVE BOTH LEADS
FROM J2 TERMINALS
CONNECT B4 FAN MOTOR BLACK
COMMON WIRE TO 9V BATTERY
NEGATIVE TERMINAL
FAN MOTOR CONTROL
BLACK LEAD
BROWN LEAD
FAN MOTOR (B4) TEST
FULLY CHARGED 9V BATTERY
This is a test that will verify that the motor does operate.
J2
1. Verify main (240 volt) power if OFF to unit.
2. Remove both wires (brown and black) from the J2 terminal on the fan motor
control (A177).
3. Room thermostat should be in OFF position (unit in idle mode − no heating or
cooling demands)
4. Turn main power (240 volt) ON to unit.
5. Connect 9 Volt battery to fan motor plugs as noted in picture below.
6. Fan motor should run at a reduced fan speed.
7. If fan motor does not run, then replace fan motor assembly.
NEGATIVE TERMINAL POSITIVE TERMINAL
CONNECT B4 FAN MOTOR WIRE
TO 9V BATTERY POSITIVE
TERMINAL
V
Figure 23. B4 Fan Motor Test
Page 44
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XP21
HEAT PUMP CONTROL (A175) UNIT NOMINAL CAPACITY CODE CONFIGURATION
In a communicating system, if the room thermostat is indicating either a error code 313, indoor and outdoor unit capacity
mismatch error code, or error code 34, must program unit capacity for outdoor unit. Use the procedure provided in figure 24
to set the unit nominal capacity code.
When the required Unit Capacity Code
is displaying on the LEDs, remove
FIELD TEST jumper from pins (E33).
LEDs will continue to display the
selected unit capacity code for two (2) minutes
before defaulting back to the idle mode
{simultaneous slow flash}, or until the 24 volt
power is cycled to the air conditioner control.
START
Set room thermostat
to OFF
Go to control terminal
strip
Remove R wire
from control (24 volt
AC power)
icomfortt
enabled
Remove control
wires from i+ and
i− terminals
Non − icomfortt
enabled
Remove control
wire from Y1
terminal
Place jumper
on FIELD TEST
(E33 pins)
Connect R wire to control
(24 volt AC power)
DS14 (Red)
DS11 (Green)
TERMINAL STRIP
Status LED lights DS11
and DS14 will blink and
then on continuously.
Once both LEDs are on
continuously then
remove jumper
immediately from E33.
Place jumper on FIELD
TEST (E33 pins) within 2 to
4 seconds after removal
The control´s DS11 and DS14 LEDs will
start blinking the Unit Nominal Code at
three (3) second intervals starting at
1−ton through to 6−ton. If a code is not
selected, the control will cycle one more
time through the codes before defaulting
back to the idle mode (simultaneous
slow flash).
Long blink ON red LED (DS14) to
indicate tonnage and solid ON green
LED (DS11) to indicate ½ tonnage.
Model
DS11
Green
LED
Size
DS14
Red LED
−012
−018
−024
−030
−036
−042
−048
−054
−060
−066
−072
1−ton
1.5−ton
2−ton
2.5−ton
3−ton
3.5−ton
4−ton
4.5−ton
5−ton
5.5−ton
6.0−ton
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
1 long flash
1 long flash
2 long flashes
2 long flashes
3 long flashes
3 long flashes
4 long flashes
4 long flashes
5 long flashes
5 long flashes
6 long flashes
FINISH
Field Test
(E33)
DS12
Communicating
Status Indicator
Sensor harness
must be attached
to air conditioner
control.
Remove R wire from
air conditioner control
(24 volt AC power)
Connect R wire to
control (24 volt AC
power)
Reconnect any control
wiring previously
removed.
If jumper is not removed
immediately from E33, then DS11
and DS14 LEDs will resume
blinking again.
Remove R wire
from control (24 volt
AC power)
Jumper
removed
successfully
YES
NO
Figure 24. Heat Pump Control (A175) Unit Nominal Capacity Code Configuration
Page 45
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XP21
MULTI−FUNCTION TEST PINS (E33)
Placing the jumper on the field test pins (E33) using a specific sequence allows the technician to:
Clear short cycle lockout
Clear five−strike fault lockout
Cycle the unit in and out of defrost mode
Manually place the unit in defrost mode to clear the coil
When Y1 is energized and 24V power is being applied to the heat pump control (A175), a test cycle can be initiated by placing a jumper on the heat
pump control’s TEST pins for 2 to 5 seconds. If the jumper remains on the TEST pins (E33) for longer than five seconds, the heat pump control will
ignore the jumpered TEST pins and revert to normal operation.
The heat pump control will initiate one test event each time a jumper is placed on the TEST pins. For each TEST the jumper must be removed
for at least one second and then reapplied.
Y1 Active
Place a jumper on TEST pins for
longer than one second but less
than two seconds.
Clears any short cycle lockout and
five strike fault lockout function, if
applicable. No other functions will
be executed and unit will continue in
the mode it was operating.
Place a jumper on TEST pins for
more than two seconds.
Clears any short cycle lockout and
five strike fault lockout function, if
applicable.
If in HEATING Mode
If in DEFROST Mode
No further test mode operation will
be executed until the jumper is
removed from the TEST pins and
reapplied.
If no ambient or coil sensor fault
exist, unit will go into DEFROST
MODE.
If ambient or coil faults exist (open
or shorted), unit will remain in
HEAT MODE.
The unit will terminate defrost and
enter HEAT MODE uncalibrated
with defrost timer set for a maximum
34 minute test.
If jumper on TEST pins remains in
place for more than five seconds.
The unit will return to HEAT MODE
un−calibrated with defrost timer set
for 34 minutes.
If jumper on TEST pins is removed
before a maximum of five seconds.
The unit will remain in DEFROST
MODE until termination on time or
temperature.
O Line Status
INACTIVE
ACTIVE
If in COOLING Mode
NOTE If ambient or coil fault is detected, the heat
pump control will not execute the TEST mode.
NOTE Heat pump control cannot be force into
defrost mode when the ambient temperature input
from the RT13 sensor is above 65ºF (18ºC).
Figure 25. Heat Pump Control’s Multi−Function Test Pins (E33) (101796−XX Only)
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XP21
FAN MOTOR SURGE PROTECTION
(XP21−XXX−230−01 only)
Surge Protector (metal oxide varistor) − A component de-
signed to protect electrical devices from voltage spikes that
are 3−to−4 times the normal circuit voltage (See figure 26 for
illustration of component).
How it works: It is essentially a batch of metallic−oxide
grains separated by insulating layers. Repeated voltage
surges break down the insulating layers, lowering the overall resistance and eventually causing the device to draw too
much current and trip whatever over−current protection is
inherent in the system.
Surge Protector Check: They are supposed to be located
beyond the line fuse (though possibly not always). In this
case, where the line fuse blows or circuit breaker trips but
there is no visible damage to the surge protector, the simplest test may be to just temporarily remove the surge
protector and see if the problem goes away.
See figure 1 for location of the surge protection device in
the unit control box area.
Figure 26. Fan Motor Surge Protection Device
(XP21−XXX−230−01 only)
FAN MOTOR SURGE PROTECTION
(XP21−XXX−230−02 and later)
Starting with the reference build above, the fan motor surge
protection is in built into the fan motor itself.
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XP21
OUTDOOR CONTROL − PART NUMBER 103369−XX
Jumper Settings
55
50
DEGREE
TARGET
45
DEGREE
TARGET
40
DEGREE
TARGET (DEFAULT)
55
50
45
40
55
50
45
40
55
50
45
40
55
50
45
40
DEGREE
TARGET
100
90
DEGREE
TARGET
70
DEGREE
TARGET
50
DEGREE
TARGET
100
90
70
50
DEGREE
TARGET
100
90
70
50
100
90
70
50
100
90
70
50
30
0
30
SECOND DELAY
SECOND DELAY
0
Cut for Humiditrol® − Enhanced
Dehumification Accessory (EDA)
applications.
SECOND−STAGE LOCK−IN
TEMPERATURE
(HP ONLY) J4
J1 (HP ONLY)
J3 ALL UNITS)
DS TO R TWO−STAGE UNIT
ONLY)
(TWO−STAGE HEAT
PUMP ONLY) J2
DEFROST TERMINATION TEMPERATURE
COMPRESSOR SHIFT DELAY
1. Set defrost termination temperature (J1) to ensure a completely clear coil before
termination of defrost. Low outdoor temperatures could require higher defrost
termination temperature setting. Factory default setting is 50ºF. If jumper is removed
or missing, default is 90ºF.
IMPORTANT All mandatory configuration requirements (jumpers and link) MUST
be completed prior to starting unit.
2. Second−stage lock−in factory default setting for J2 is 40ºF. If jumper is removed or
missing, default is OFF.
FAN CYCLING
ON
OFF
JUMPER ON
FAN ON FOR 5 MINUTES
DISABLE (DEFAULT)
JUMPER OFF
(DEFAULT)
NOTE Fan cycling routine when activated will cycle the
fan ON for five minutes if the outdoor ambient air
temperature is between 15ºF and 35ºF and the
compressor has been OFF for 25 to 30 minutes. This
option is to help reduce the potential for ice build up on the
orifice ring during system OFF cycles that are greater
than 25 to 30 minutes.
SEE NOTE ABOVE FOR FURTHER DETAILS.
100
90
70
50
(DEFAULT)
(DEFAULT WHEN JUMPER IS
REMOVED OR MISSING)
90
Non−Communicating System
The unit will operate based on jumper settings and R TO DS link on
the MAIN CONTROL. All unit setting changes must be done at the
MAIN CONTROL. The Lennox ComfortSense 7000 thermostat
may be used, as well as other non−communicating electronic−only
thermostats.
Communication System
The jumper settings and link are default settings and ONLY control
system operation if configuration settings in the icomfort
thermostat are not available.
The Lennox icomfort thermostat must be used in
communicating applications. Refer to page 51 for further information.
7−SEGMENT
DISPLAY
PUSH
BUTTON
Set up of jumpers on
replacement outdoor
control.
MANDATORY CONFIGURATION REQUIREMENTS
HEAT PUMP CONTROL TWO−STAGE OPERATION
NOTE − LINK NOT APPLICABLE TO
ONE−STAGE UNITS. CUTTING LINK WILL
HAVE NO AFFECT ON OPERATION OF
ONE−STAGE UNITS
.
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XP21
Configuring Unit
For the new outdoor control to work correctly, it MUST BE programmed for unit type (AC or HP and number of stages), unit
capacity and outdoor fan profile (RPM). The new outdoor control has an auto−detection feature that will determine the unit
type. The following set up procedures MUST be done on all new outdoor controls.
Auto−Detection of Unit Type (air conditioner or heat pump and number of stages)
During initial power−up the control will auto−detect the unit
type. The unit type is determine by what is connected to
various outputs on the new control.
OUTDOOR CONTROL
SEVEN−SEGMENT
DISPLAY
PUSH BUTTON
BLACK
BLACK
Anytime there is a connection to O OUT terminal, the
control will detect the unit type as a heat pump.
Anytime there is no connection to O terminal, the
control will detect the unit type as a air conditioner.
Anytime there is a connection to Y2 OUT terminal,
the control will detect the unit as two−stage.
Anytime there is no connection to Y2 terminal, the
control will detect the unit as one−stage.
If the control auto−detects the unit type incorrectly it may be due to the
control being miswired, loose connection or missing connection to
the required control output terminal. Disconnect power to the control,
verify connections, correct wiring and reconnect power. Verify that
the correct unit type is displayed on the seven−segment display.
The unit capacity and fan speed are manually
configured. Until those parameters are configured the
7−segment display will show 3 bars for the unit capacity
and fan speed.
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XP21
Configuring Unit Type
During initial power−up the control will auto−detect the unit
type. The unit type is automatically determine by what is
connected to Y2 OUT and/or O OUT on the control. The
unit type can be permanently stored in the control’s memory by
manually configuring the unit type using the following procedure.
Typically the capacity and fan speed will not be configured and will
display the three dashes for each. For manual configuration of the
unit type, proceed as indicated.
Outdoor control is in IDLE mode
(No heating or cooling demand)
To enter unit type
configuration, push and hold
button next to single character
display until dash symbol
appears and immediately
release button. Once dash
starts blinking, proceed to
next step.
Turn room thermostat
to OFF
Push and hold button until the solid
sequence is displayed on the
seven−segment display and then
immediately release the button.
If three horizontal bars display in any part of the 7−segment
string during power up, the outdoor control did not store that
configuration. (Unit type, capacity or fan RPM. If this happens,
the configuration sequence for that section of the string must
be repeated.
Yes
No
OUTDOOR CONTROL
SEVEN−SEGMENT
DISPLAY
PUSH BUTTON
One stage air conditioner
Two stage air conditioner
One stage heat pump
Two stage heat pump
During power up of the outdoor control, the seven−segment display will show the
stored number of stages unit type, capacity and outdoor fan speed.
PAUSE PAUSE
TWO STAGE
HEAT PUMP
CAPACITY
(3−TON)
FAN
PROFILE
Press and hold the button
during the cycling display.
The outdoor control will store unit type in
memory and will automatically exit the configuration and reset control.
1. When the correct unit type is displayed,
release button immediately. [Display will
start flashing]
2. Push and hold button until selection stops
flashing during one of the three cycles.
[Release the button]
3. If selection is not made during those three
cycles the control will return to idle mode.
SELECTED
NOT
SELECTED
Unit Type / Number of Stages
SELECTED
NOT
SELECTED
[This configuration sequence allows the installer to select
a unit type (number / letter combination) that matches the
outdoor type and number of stages.]
[The sequence will
repeat 5 times and if a
selection is not made the
control will return to idle
mode.]
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XP21
END
SEE
NOTE 3
SEE NOTE 2
Outdoor control is in IDLE mode
(No heating or cooling demand)
To enter unit capacity or fan
profile configuration, push
and hold button next to single
character display until dash
symbol appears and
immediately release button.
Once dash starts blinking,
proceed to next step.
Turn room thermostat
to OFF
Push and hold button until the solid
or sequence is displayed on
the seven−segment display and then
immediately release the button. This
configuration sequence allows the
installer to select a unit type (number
/ letter combination) that matches
the outdoor unit type and number of
stages.
If three horizontal bars display in any part of the 7−segment
display string during power−up, the outdoor control did not
store that configuration (unit type, capacity or fan profile). If
this occurs, the configuration sequence for that section of the
string must be repeated.
Yes
No
OUTDOOR CONTROL
SEVEN−SEGMENT
DISPLAY
PUSH BUTTON
During power up of the outdoor control, the seven−segment display will show the
stored number of stages unit type, capacity and outdoor fan speed.
PAUSE PAUSE
Either the or sequence
will repeat 5 times and if a
selection is not made the
control will return to idle mode.
Press and hold the button
during the or cycling
display.
NOT
SELECTED
SELECTED
Configuring Unit Capacity or Fan Profile
Power−up − Unit capacity (two−digit number) and displayed
represents unit size code (outdoor unit capacity).
Unit Capacity Code
12
18
24
30
36
42
48
60
1−TON
1−1/2−TON
2−TON
2−1/2−TON
3−TON
3−1/2−TON
4−TON
5−TON
Fan Profile Code (see notes)
SELECTED
NOT
SELECTED
2−Stage Heat Pump Capacity (3−Ton) Fan Profile
UNIT CAPACITY
FAN PROFILE
1. When the correct unit capacity or fan profile is
displayed, release button immediately. [Display will start blinking]
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 will return to idle mode.
The outdoor control will store unit type in memory and will automatically exit the configuration and reset control.
During initial power up, the number of stages / unit type, unit
capacity and outdoor fan speed will appear on the 7−segment
display.
1. Determine fan motor−type (EBM or ECM).
2. Units with EBM motors − The fan motor RPM must be field
set or three bars will appear in the fan profile string section of
the 7−segment display. The factory default is 700 RPM.
3. Units with ECM motors − The fan motor RPM is factory set
and can not be adjusted. The ECM motor speed (fan profile)
string will not appear on the 7−segment display. The fan profile
displayed is applicable only to EBM fan motor applications.
ECM fan
motor
EBM fan motor
with blades
NOTES
If three horizontal bars display in any part of the 7−segment
display string sections during power−up, the outdoor control
did not store that configuration (unit type, capacity or fan
RPM). If this happens, the configuration sequence for that
section of the string must be repeated.
SEE NOTE 1
See table 18 for
fan profile.
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XP21
Table 18. Fan RPM Profiles
Fan RPM
Profile
Model Number Stage 1
PWM %
Stage 1
RPM
Stage 2
PWM %
Stage 2
RPM
EDA Stage
PWM %
EDA Stage
RPM
0 XC/XP17−024 55 400 55 400 55 400
1 XC/XP17−030 62 450 62 450 62 450
2 Not assigned 69 500 69 500 69 500
3 Not assigned 71 550 76 550 71 550
4 XC/XP17−036 and −042 83 600 83 600 83 600
5 Not assigned 90 650 90 650 90 650
6 XC/XP17−048 and −060 92 675 92 675 92 675
7 Not assigned 97 700 97 700 97 700
8 Not assigned 48 350 55 400 27 200
9 Not assigned 55 400 62 450 27 200
10 XP21−024 58 425 69 500 27 200
11 XC21−024 65 475 76 550 27 200
12 XC/XP21−036 72 525 83 600 30 225
13 Not assigned 79 575 90 650 30 225
14 XC21−048, − 060 and
XP21−048
83 600 92 675 30 225
15 XP21−060 86 625 97 700 30 225
Seven−Segment Alert and System Status
Codes
Alert codes are displayed using the seven−segment display
located on the outdoor control.
NOTE System fault and lockout alarm code displays
takes precedence over system status (cooling, heating
stages or defrost/dehumidification).
The seven−segment will display an abnormal condition (error code) when detected in the system. A list of the codes
are shown in table 19.
RESETTING ALERT CODES
Alert codes can be reset manually or automatically:
4. Manual Reset
Manual reset can be achieved by one of the following
methods:
Disconnecting R wire from the main control’s R ter-
minal.
Turning the indoor unit off and back on again
After power up all existing codes are cleared.
5. Automatic Reset
After an alert is detected, the main control continues to
monitor the unit’s system and compressor operations.
When/if conditions return to normal, the alert code is
turned off automatically.
Reconfiguring Outdoor Control using
icomfortt Thermostat
If any component of the HVAC system has been changed,
e.g. replacing an outdoor sensor, reconfiguring the system
will be required. To begin reconfiguring a system, press the
setup tab. Note: Even though its in a communicating system, the fan profile will need to be set because the
icomfort thermostat does not know what the profile
should be.
Refer to the icomfort Thermostat Installer Setup Guide
for configuration procedures.
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Table 19. Seven−Segment Display Alert Codes
NOTE System fault and lockout seven−segment display alarm codes takes precedence over system status codes (cooling, heating stages or defrost/dehumidification). Only the latest active fault or lockout alarm code if present will be displayed.
If no fault or lockout codes are active, then system status are routinely displayed.
Alert
Codes
Alarm Description Possible Causes and Clearing Alarm
E 105
The outdoor unit has lost
communication with the rest of the
system.
Equipment is unable to communicate. This may indicate the existence of other alarms / codes. In
most cases errors are related 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. This is a self−recoverable error.
E 120
There is a delay in the outdoor unit
responding to the system.
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 thermostat. Check all wiring
connections. Cleared after unresponsive device responds to any inquiry
E 124
The icomfort thermostat has lost
communication with the outdoor unit for
more than 3 minutes.
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.
E 125
There is a hardware problem with the
outdoor unit control.
There is a control hardware problem. Replace the outdoor control if the problem prevents operation
and is persistent. The alarm / fault is cleared 300 seconds after the fault recovers
E 126
There is an internal communication
problem with the outdoor unit control.
There is an internal hardware problem on the control. Typically the control will re−set itself. Replace
the control if the problem prevents operation and is persistent. The alarm / fault is cleared 300 seconds after the fault recovers.
E 131
The outdoor unit control parameters are
corrupted
Reconfigure the system. Replace the control if heating or cooling is not available
E 180
The icomfort thermostat has found a
problem with the outdoor unit’s ambient
sensor.
In normal operation after outdoor control recognizes sensors, the alarm will be sent if valid
temperature reading is lost. Compare outdoor sensor resistance to temperature/resistance charts
in unit installation instructions. Replace sensor pack if necessary. At the beginning of (any)
configuration, furnace or air−handler control will detect the presence of the sensor(s). If detected
(reading in range), appropriate feature will be set as ’installed’ and shown in the icomfort
thermostat ’About’ screen. The alarm / fault will clear upon configuration, or sensing normal values.
E 401
Either the compressor ran for more than
18 hours continuously.
Compressor ran more than 18 hours to satisfy a single thermostat demand. If the unit is 2−stage, the
high−speed will lock−out and the unit will run at low−speed. If it is a HP and ODT <65ºF, the system will
not raise an alarm. Confirm that the system is properly charged with refrigerant. Check for stuck
reversing valve, excessive cooling load and properly sized equipment. Confirm that the evaporator
coil is clean. The alarm clears after 30 consecutive normal run cycles or a power reset.
E 403
The compressor ran for less than 3
minutes to satisfy a thermostat demand
(short−cycling)
Compressor runs less than 3 minutes to satisfy a thermostat demand (short−cycling). Confirm that
the system is properly charged with refrigerant. Check the condensation float switch and TXV. The
alarm clears after 4 consecutive normal compressor run cycles or a power reset.
E 409
The secondary voltage for the outdoor
unit has fallen below 18VAC. If this
continues for 10 minutes, the system
will shut down.
Secondary voltage is below 18VAC. After 10 minutes, operation is discontinued. Check the indoor
line voltage, transformer output voltage. The alarm clears after the voltage is higher than 20VAC for
2 seconds or after a power reset.
E 410
The outdoor unit pressure is below the
required limit.
Unit pressure is below the lower limit. The system is shutdown. The low pressure switch for
HFC−410A will open at 40PSIG and close at 90PSIG. 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 closes or after a
power reset
E 411
The low pressure switch has opened 5
times during one cooling cycle. As a
result, the system will shutdown.
Open low pressure switch error count reached 5 strikes. The low pressure switch for R410A will
open at 40PSIG and close at 90PSIG. 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 a power reset
E 412
The outdoor unit pressure is above the
required limit. The system will shut
down.
Unit pressure is above the upper limit. System is shut down. The high pressure switch for HFC−410A
will open at 590PSIG and close at 418PSIG. Confirm that the system is properly charged with
refrigerant. Check condenser fan motor, TXV, indoor unit blower motor, stuck reversing valve or
clogged refrigerant filter. Confirm that the outdoor unit is clean. The alarm clears after 4 consecutive
normal compressor run cycles, the pressure switch closes or a power reset
E 413
The high pressure switch has opened 5
times during one cooling cycle. As a
result, the icomfort thermostat will
shutdown.
Open high pressure switch error count reached 5 strikes. System is shut down. The high pressure
switch for HFC−410A will open at 590PSIG and close at 418PSIG. Confirm that the system is properly charged with refrigerant. Check condenser fan motor, TXV, indoor unit blower motor, stuck reversing valve or clogged refrigerant filter. Confirm that the outdoor unit is clean. The alarm clears after a
power reset.
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XP21
Table 20. Seven−Segment Display Alert Codes (continued)
Alert
Codes
Alarm Description Possible Causes and Clearing Alarm
E 414
The discharge line temperature is higher than the recommended upper limit of
279ºF.
Discharge line temperature is > 279ºF. Confirm that the system is properly charged with refrigerant.
Check system operating pressures and compare to unit charging charts in installation manual.
Confirm that the outdoor unit is clean. The alarm clears after the discharge temperature is < 225ºF.
E 415
The discharge line temperature has
been consistently higher than the recommended upper limit of 279ºF.
Discharge line high temperature error count reached 5 strikes. Confirm that the system is properly
charged with refrigerant. Check system operating pressures and compare to unit charging charts in
installation manual. Confirm that the outdoor unit is clean. The alarm clears after the discharge temperature is < 225ºF. The alarm clears after a power reset.
E 416
The outdoor coil sensor is either open,
short−circuited or the temperature is out
of sensor range. As a result the outdoor
unit control will not perform any defrost
tempering.
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 will still heat or 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.
E 417
The outdoor unit discharge sensor is either open, short−circuited or the temperature is out of sensor range. As a result the outdoor unit control will not perform any defrost tempering.
Outdoor unit control detects open or shorted discharge sensor, or temperature that is out of
discharge sensor range. Check the resistance of the discharge sensor and compare to
temperature resistance chart − replace if needed. Reset by replacing the discharge sensor. This
fault is detected by allowing the unit to run for 90 seconds before checking discharge sensor
resistance. If the discharge sensor resistance is not within range after 90 seconds, the board will
count one fault. After 5 faults, the board will lock out. Check for proper sensor reading and
attachment to line. The alarm clears after a power reset.
E 418 There is a faulty W output circuit.
Faulty W output circuit. Confirm that the unit is not running. Check for mis−wiring. Disconnect
thermostat lines from W and verify 24VAC on the W. If 24VAC is present, replace the board.
E 419
The W output on the outdoor unit has re-
ported more than 5 errors. As a result,
the system has shutdown the outdoor
unit.
W output hardware fault count reached 5−strikes.
E 420
The heat pump defrost cycle has taken
more than 20 minutes to complete.
Defrost cycle lasts longer than 20 minutes. This alarm is applicable with non−communicating heat
pump system only. Check heat pump defrost operation. The alarm is cleared after the "W1" signal is
removed.
E 421
The W output terminal on the outdoor
unit is not wired correctly.
Voltage sensed on W and O when Y1 thermostat input is deactivated. Another device or wiring fault
is energizing W Check wiring. The alarm clears when wiring is corrected or after a power reset.
NOTE Additional codes may be found in icomfortt thermostat manual.
Table 21. Outdoor Control Seven−Segment Unit Status Displays
Description Example of Display
Power up / Reset: Unit type and number of stages is displayed.
Verify configuration with information published on the unit nameplate. If the information is incorrect, refer to flow chart Manually
Configuration of Unit Type to re−configure control.
1 Stage AC: 1AC
2 Stage AC: 2AC
1 Stage AC: 1HP
1 Stage AC: 2HP
POWER−UP 7−SEGMENT DISPLAY STRING
Unit Type / Stages
No Capacity No Fan Profile
Power up / Reset following display of self−discovered configuration: Unit nominal capacity is
displayed, if not programmed then three horizontal
lines and the decimal point are displayed for 2 seconds.
POWER−UP 7−SEGMENT DISPLAY STRING
Unit Type / Stages
Capacity No Fan Profile
Power up nominal capacity display of an XP21−036: 36
Power up / Reset following display of nominal
capacity: Fan Profile code. (a single or two digit
number) See table 18 for applicable fan RPM profile.
POWER−UP 7−SEGMENT DISPLAY STRING
Unit Type / Stages
Capacity
Fan Profile
Displays the number of the selected fan profile. 3
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XP21
Table 8. Outdoor Control Seven−Segment Unit Status Displays (continued)
Description Example of Display
Idle Mode: Decimal point blinks at 1 Hz
Idle Mode: Decimal point blinks at 1 Hz (0.5 second on, 0.5 second off).
Display OFF.
Soft Disabled: Top and bottom horizontal line and decimal point
blink at 1 Hz.
Soft Disabled: Top and bottom horizontal line and decimal point blink at 1
Hz (0.5 second on, 0.5 second off). Note: Control should be replace.
O.E.M test mode
All segments flashing at 2 Hz (unless error is detected) Note: Control
should be replace.
Anti−Short Cycle Delay
Middle line shall blink at 1 Hz for 2 seconds, followed by a 2 second display
of the rounded up number of minutes left in the timer (2 minutes 1 second
shall be displayed as 3"). The Anti−Short Cycle Delay time remaining is
displayed whenever the delay is active.
Cooling Stage: Shows what stage of cooling is currently operating.
Following string is repeated if second stage cooling is active with outdoor
fan speed set at 700 RPM. Note: A − If available, displays outdoor ambient
temperature.
pause pause
Heat Pump Stage: Shows what stage of heat pump is currently
operating.
Following string is repeated if first stage heat pump is active with outdoor
fan speed set at 600 RPM. Note: A − If available, displays outdoor ambient
temperature.
pause pause
Defrost Mode: Shown only while in an active defrost.
Following string is repeated if defrost is active while unit was in 1st stage
heat pump heating mode:
pause pause
Dehumidification mode: Shows that the unit is providing dehumidification instead of straight cooling.
Following string is repeated if dehumidification is active with outdoor fan
speed set at 225 RPM:
pause pause
Diagnostic recall: Shows the last 10 stored diagnostic error
codes.
If first error is , second : pause pause pause
Next codes (up to 10) are show using same method.
If there is no error codes stored: E pause 0 0 0
Fault Memory clear
After the fault memory is cleared following string is displayed with 0.5 seconds character on/off time:
pause
Active error in outdoor control Idle mode: Shown all active
error(s) codes.
Following string is repeated if Error E125 and E201 are present:
pause
Active error in run mode: Shown current status and all active
error(s) codes.
Following string is repeated if Error E311 is present while blower speed at
700RPM:
pause
Outdoor Ambient Temperature (OAT): Any time OAT is sensed
in operating range value is displayed if unit is in diagnostic and
non−diagnostic modes.
Following string is repeated if second stage cooling is active with outdoor
fan speed set at 650 RPM and OAT is 104
o
F:
pause pause pause
Outdoor Coil Temperature (OCT): Any time OCT is sensed in
operating range value is displayed if unit is in diagnostic mode.
Following string is repeated if 2nd stage heat is active with outdoor fan
speed set at 550 RPM and OCT is 25o F:
pause pause pause
Discharge Line Temperature (DIS): Any time DIS is sensed in
operating range value is displayed if unit is in diagnostic mode.
Following string is repeated if 2nd stage cooling is active with outdoor fan
speed set at 650 RPM and DIS is 185
o
F:
pause pause pause
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XP21
Table 22. Error Recall Menu Options
Error Code Recall Mode (Note − control must be in idle mode)
Solid
To enter error code recall mode, push and hold button until solid E appears, then release button. Control will display
up to 10 error codes stored in memory. If E000 is displayed, there are no stored error codes.
Solid
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.
Solid
To clear error codes stored in memory, continue to hold push button while the 3 horizontal bars are displayed. Release push button when solid c is displayed.
Blinking
Hold push button for three seconds to confirm command to delete codes. Error codes are cleared.
*Note once the error history is deleted it cannot be recovered. After the history is deleted, the unit will reset itself.
Table 23. Field Test and Program Menu Options
Display
Display and action (normal operation) Display and action (configuration and test mode)
Power −UP
Display string displays > number of unit stages > pause > or unit > pause > unit capacity in BTUs > pause > RPM setting of
outdoor fan. If 3 horizontal bars are displayed during any sequence of this string, it indicates that the specific parameter is not
configured.
Idle mode decimal blinks at 1 Hertz > 0.5 second ON, 0.5 second OFF
in the display string represents the ambient temperature in F
at the outdoor sensor on the outdoor unit.
Enter test mode: Display will string active error code(s) ,
ambient
, coil and discharge temperature in F at out-
door unit.
− dehumidification mode string > pause> (Outdoor fan)
RPM > pause >
(ambient temp displayed) > pause > repeat
mode. IMPORTANT: On 2−stage unit R to DS link must be cut
and correct RPM outdoor fan profile selected for outdoor fan to
operate at lower RPM speed when EDA is active.
Enter test mode: Forced defrost. (System must be configured as HP. Unit must be running in heating mode). Test defrost will terminate when coil terminate temperature is
reached (or 10 seconds, whichever is longer) or 14 minutes if
coil temperature remains below terminate temperature or by
pushing button down for less than 2 seconds. Enter
test
mode: Display will string active error codes
, ambient , coil
and discharge temperature in F at outdoor unit.
d F displays when system is in defrost mode − unit must be running in heating mode, outdoor ambient must be below 65F and
outdoor coil temperature must be below defrost termination temperature.
in the display string indicates RPM setting output on
terminals PWM and com (used with EBM motors). RPM
displayed does not apply to motor connected on ECM Y1 and
ECM Y2.
Enter test mode: Control outputs DC Voltage onto PWM
and com terminals. Outdoor fan will cycle ON for 10 minutes
at 490 RPM. To exit test − Push and hold button until three horizontal bars display. Release button, outdoor fan will cycle
OFF. (Test DOES NOT output DC voltage to ECM Y1 and
ECM Y2 terminals)
Heat stage 1 string display > pause > outdoor fan RPM displayed > pause > (ambient temperature displayed > pause >
repeat mode.
Heat stage 2 string display > pause > outdoor fan RPM displayed > pause > ambient temperature displayed > pause > repeat
mode.
Cool stage 1 string display > pause > outdoor fan RPM displayed > pause > (ambient temperature displayed > pause >
repeat mode.
Cool stage 2 string display > pause > outdoor fan RPM displayed > pause > (ambient temperature displayed > pause > repeat
mode.
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XP21
Configuring Outdoor Fan Speed (Note − Control must be in Idle Mode)
Display Code Procedure
Solid
Release push button Allows user to select outdoor fan RPM profile. IMPORTANT: New control may need to be
manually configured to validate outdoor unit fan RPM setting is correct for unit capacity. Refer to RPM table on unit
wiring diagram.
Blinking
Push and hold button Outdoor control will display a fan RPM profile 3 seconds. When the correct fan RPM profile
is displayed, release button. Selected code will flash for a 10 second period. During that period, hold push button for
3 seconds to store code. Once code is stored control will automatically exit field test mode. If 10 second period
expires or push button is held less than 3 seconds, control will automatically exit field test mode and go into idle
mode without storing fan RPM profile. Repeat procedure to correct.
Configuring Unit Capacity (Note − Control must be in Idle Mode)
Solid
Release push button Allows user to select Unit Capacity. IMPORTANT: Field replacement control may need to be
manually configured to validate outdoor unit capacity. Refer to unit nameplate model number for capacity in 1,000 of
BTUs. (18, 24, 30 ,36,42 48, 60)
Blinking
Push and hold button Control will display unit capacity number 3 seconds. When the correct unit capacity number
is displayed, release button. Selected code will flash for a 10 second period. During that period, hold push button for
3 seconds to store code. Once code is stored control will automatically exit Field Test Mode. If 10 second period
expires or push button is held less than 3 seconds, control will automatically exit field test mode and go into idle
mode without storing unit capacity Number. If this happens, configuring procedure must be repeated.
Table 10. Field Test and Program Menu Options (continued)
Display Code Procedure
Solid
Release push button Allows user to select type and number of stages on outdoor unit.. IMPORTANT: Field re-
placement control may need to be manually configured to validate outdoor unit fan RPM setting is right for unit capacity. See RPM table on unit wiring diagram for proper RPM settings. Type and number of stages: 1AC, 2AC, 1HP,
2HP – AC – air conditioning and HP – Heat Pump
Blinking
Push and hold button Control will display type and number of stages 3 seconds. When the correct type and number of stages is displayed, release button. Selected code will flash for a 10 second period. During that period, hold
push button for 3 seconds to store code. Once code is stored control will automatically exit field test mode. If 10
second period expires or push button is held less than 3 seconds, control will automatically exit field test mode and
go into idle mode without storing type and number of stages. If this happens, configuring procedure must be repeated.
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XP21
APPLICABLE TO ALL VERSIONS
Compressor Information and Testing
The XP21 uses either a ZPSK4 or ZPSK5 depending on model number. See table 25 for applicable compressor use by
model number.
ELECTRICAL CHARACTERISTICS
Table 24 provides information concerning the electrical characteristics of both the ZPSK4 and ZPSK5 (single−phase).
Table 25. Compressor Electrical Characteristics Comparison
Lennox Model
Lennox
Compressor
Part Number
Copeland Model Voltage Phase LRA RLA
Minimum
Circuit
Ampacity
Max Fuse
/ Ckt Bkr
Run
Capacitor
Start Kit
XP21−024−230−01 thru −04 100504−01 ZPS20K4E−PFV
208/230 1
52 10.3 14.9 25 35/5 370 63W22
XP21−024−230−05 103137−01 ZPS20K5E−PFV 58.3 11.7 20 25 35/5 440 10J42
XP21−036−230−01 thru −03 100504−02 ZPS30K4E−PFV 82 16.7 22.9 35 40/5 440 63W23
XP21−036−230−04 103137−02 ZPS30K5E−PFV 83 15.3 21.1 35 40/5 440 10J42
XP21−048−230−03 100504−03 ZPS40K4E−PFV 96 21.2 28.5 45 45/10 440 10J42
XP21−048−230−04 103137−03 ZPS40K5E−PFV 104 21.2 28.5 45 30/5 440 12J90
XP21−060−230−03 100504−14 ZPS49K4E−PFV 118 23.1 30.9 50 80/7.5 440 63W24
XP21−060−230−04 103137−04 ZPS49K5E−PFV 153 28.8 38 60 40/5 440 12J90
ELECTRICAL CHARACTERISTICS
External mechanical differences between the ZPS*K4 and ZPS*K5 are minimal. The suction and discharge tube height differences are less than 0.75". The ZPS40K5 compressor is 0.50" taller than the ZPS40K4. All other ZPS*K5 compressors are
shorter than the equivalent ZPS*K4 compressor. The mounting configuration is the same for both compressor families. The
compressor frame sizes are different and a smaller crankcase heater may be required. In addition, there are difference sin
mounting grommets because of the different frame sizes.
K4 COMPRESSOR MODULATING SOLENOID
These controls convert the 24 volt AC
power to 24 Volt DC. The solenoid is
pulled in with 24 volts DC and then the
coil is held in by pulsing the voltage
between 6 and 18 volts DC.
SOLENOID PLUG (24VDC INPUT)
SOLENOID PLUG (24VDC INPUT /
24VDC OUTPUT)
This control outputs 24VAC on Y2 and
OUT. The plug on the compressor has
a rectifer that converts the 24VAC to
24VDC. The solenoid is pulled in with
24VDC.
Figure 27. K4 Compressor Modulating Solenoid
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XP21
K5 COMPRESSOR MODULATING SOLENOID
Standard wiring without LSOM or icomfort
control with
built−in LSOM
Wiring with the LSOM or icomfort
control with the
built−in LSOM
Figure 28. K4 Compressor Modulating Solenoid
COMPRESSOR INTERNAL SOLENOID (L34) TEST
PROCEDURE
IMPORTANT
When checking compressor for two−stage operation,
always cycle Y1 to Y2 from terminals on the outdoor
control integrated LSOM function to the room thermostat
connections. DO NOT cycle second−stage (Y2) of
compressor by unplugging the 24VDC solenoid input to
the outdoor control integrated LSOM function (E34) end
of plug. The outdoor control integrated LSOM function
will only output a 6 to 18VDC signal which will be
insufficient voltage to pull the solenoid coil in for second
stage.
IMPORTANT
This performance check is ONLY valid on systems that
have clean indoor and outdoor coils, proper airflow over
coils, and correct system refrigerant charge. All components in the system must be functioning proper to correctly perform compressor modulation operational
check. (Accurate measurements are critical to this test as
indoor system loading and outdoor ambient can affect
variations between low and high capacity readings).
Tools required
Refrigeration gauge set
Digital volt/amp meter
Electronic temperature thermometer
On-off toggle switch
STEP A Confirm low to high capacity compressor
operation
Procedure
1. Turn main power OFF to outdoor unit.
2. Adjust room thermostat set point above (heating operation on heat pump) or below (cooling operation) the
room temperature.
3. Remove control access panel. Install refrigeration
gauges on unit. Attach the amp meter to the common
(black wire) wire of the compressor harness. Attach
thermometer to discharge line as close as possible to
the compressor.
4. Cycle main power ON.
5. Confirm Y1 operation only.
6. Allow pressures and temperatures to stabilize before
taking any measured reading (may take up to 10 minutes).
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XP21
7. Record all of the readings for the Y1 demand on table
27.
8. Energize Y2 demand.
9. Allow pressures and temperatures to stabilize before
taking any measured reading (this may take up to 10
minutes).
10. Record all of the readings of Y2 demand on table 27.
11. Compare Y1 to Y2 readings. Readings match table 27
the proper operation is verified. If readings do not
match, proceed to Step A.
NOTE On new installations or installations that have
shut down for an extended period of time, if the compressor
does not cycle from low−stage to high−stage on the first attempt, it may be necessary to recycle the compressor back
down to low−stage and back up to high−stage a few times in
order to get the bypass seals to properly seat. It might be
necessary to restrict the air flow over the indoor coil (heating) or outdoor coil (cooling) to maintain pressures high
enough to determine pressure differences between low
and high stages.
STEP 2 Verify Compressor Solenoid has Correct
Ohm Values.
1. Turn main power OFF to outdoor unit (main power and
low voltage).
2. Unplug the 2−pin solenoid plug from the fusite connection on the compressor.
SOLENOID PINS ON COMPRESSOR
FUSITE.
Figure 29. Testing
Figure 30.Solenoid Pins
3. Using a multi−meter set on ohms, check the ohms
valve of the solenoid coil in the compressor and
compare the value to table 26.
Table 26. Ohm Reading
Compressor
Family
Compressor
Model
Solenoid Resistance
ZPS*K4
All Models
33.6 V
ZPS*K5
Source A 1640 V
Source B 350 V
NOTE − There are 2 ohm readings for the solenoids used in
the ZPS*K5 compressor.
STEP 3 Verify solenoid plug has DC output voltage.
1. Turn main power OFF to outdoor unit (main power and
low voltage).
2. Unplug the 2−pin solenoid plug from the fusite connection on the compressor.
3. Turn main power ON and input a 2−stage demand to
the outdoor unit.
4. Using the multi−meter set on DC volts, check the DC
volt value at the plug−in after the five (5) second Y2
delay. Voltage at the plug connections should be between 18 and 28 VDC for non−LSOM applications and
4 to 9 VDC in LSOM applications.
MULTI−METER LEADS INSERTED IN
COMPRESSOR SOLENOID PLUG−IN
Figure 31. Testing
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XP21
Table 27. Two−Stage Modulation Compressor Field Operational Checklist
Two−Stage Modulation Compressors Field Operational Checklist
Unit Readings Y1 − First Stage
Expected results during Y2
demand (Toggle switch On)
Y2 − Second Stage
COMPRESSOR
Voltage Same
Amperage Higher
CONDENSER FAN MOTOR
Amperage Same or Higher
TEMPERATURE
Ambient Same
Outdoor Coil Discharge Air Higher
Compressor Discharge Line Higher
Indoor Return Air Same
Indoor Coil Discharge Air Lower
PRESSURES
Suction (Vapor) Lower
Liquid Higher
Page 61
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XP21
System Overview
IMPORTANT
Some scroll compressor have 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 heat pump control (A175) provides the following functions:
Demand defrost algorithm
Field−selectable defrost termination temperatures
Internal switching of outputs
Compressor anti−short−cycle delay.
Five strikes lockout safety function
High (S4) and low (S87) pressure switches
Ambient (RT13), coil (RT21) and discharge line (RT28)
temperatures monitoring and protection.
COMPRESSOR PROTECTION ANTI−SHORT
CYCLE DELAY
The heat pump control protects the compressor from:
Short cycling (five minutes) when there is initial power
up
Interruption in power to the unit
Pressure or sensor trips
Delay after Y1 demand is removed.
In non−communicating systems the delay is set for 300 seconds (five minutes) and can not be changed. To override
timer when active or inactive, place a jumper on the field
test pins between 1 and 2 seconds.
In communicating system, the icomfort thermostat has a
separate built−in 5−minute non−adjustable short cycle
protection.
Resetting Anti−Short Cycle Delay (101796−XX Only)
The FIELD TEST pins (E33) on the heat pump control can
be jumpered between 1 to 2 seconds to bypass delay.
HIGH (S4) AND LOW (S87) PRESSURE SWITCHES
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 43 for low
pressure switch sequence of operation.
High Pressure Switch (HI−PS) See figure 44 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 25 psig; reset at 40.
COMPRESSOR PROTECTION FIVE−STRIKE
LOCKOUT SAFETY FUNCTION
The five−strike lockout safety function is designed to protect the unit’s compressor from damage. The five−strike
feature is used for high pressure (S4) and low (S87) pressure switch trips, high discharge temperature (RT28)
sensor input and W input fault or miswire.
Resetting Five−Strike Lockout
Once the condition has been rectified, power to the heat
pump control’s R terminal must be cycled OFF, or a jumper
placed on the FIELD TEST pins between 1− to 2−seconds to
reset the heat pump control.
Defrost System
The heat pump control (A175) 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 46) when the defrost system
starts and after each system defrost cycle. The heat pump
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 allow mounting to the outside coil tubing. The location of the coil sensor is important for proper
defrost operation (see figure 1 for location of coil sensor).
NOTE The heat pump control accurately measures the
performance of the system as frost accumulates on the
outdoor coil. This typically will translate into longer running
time between defrost cycles as more frost accumulates on
the outdoor coil before the heat pump control initiates defrost cycles.
DEFROST OPERATING MODES
The heat pump control has three operational modes which
are:
Defrost calibration and operation (see figure 46)
Defrost test (see figure 25)
DEFROST TERMINATION TEMPERATURES
The heat pump control selections are: 50, 70, 90, and
100°F (10, 21, 32 and 38°C). The jumper termination pin is
factory set at 50°F (10°C).
If the temperature jumper is not installed, the termination
temperature is 90°F (32°C). See figure 46 for on how this
settings affects defrost calibration and defrost modes.
NOTE − Colder climates could require a high discharge termination temperature setting to maintain a clear coil.
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XP21
UNIT SENSORS
Sensors connect to the heat pump control through a fieldreplaceable harness assembly that plugs into the control.
Through the sensors, the control detects outdoor ambient,
coil, and discharge temperature fault conditions. As the detected temperature changes, the resistance across the
sensor changes. Tables 29 and 30 shows how the resistance varies as the temperature changes for both type of
sensors. Sensor resistance values can be checked by ohming across pins shown in table 28.
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 28, 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.
Ambient Temperature Sensor (RT13)
The ambient sensor (location shown in figure 1) considers
outdoor temperatures below −35°F (−37°C) or above 120°F
(48°C) as a fault. If the ambient sensor is detected as being
open, shorted or out of the temperature range of the sensor, the control will not perform demand defrost operation.
The control will revert to time/temperature defrost operation and will display the appropriate alert code. Heating and
cooling operation will be allowed in this fault condition.
Coil Temperature Sensor (RT21)
This sensor (location shown in figure 1) considers coil temperatures below −35°F (−37°C) or above 120°F (48°C) to be
a fault. If the defrost coil sensor is open, shorted or out of
the temperature range of the sensor, the heat pump control
will not perform demand or time/temperature defrost operation and will display the appropriate fault code. Heating
and cooling operation will be allowed in this fault condition.
High Discharge Line Temperature Sensor (RT28)
The high discharge line temperature sensor (location
shown in figure 1 monitors temperature range and open/
short conditions. See figure 45 for the high discharge line
temperature sensor sequence of operation.
Table 28. Sensor Temperature / Resistance Range
Sensor
Temperature
Range °F (°C)
Resistance values
range (ohms)
Pins/Wire
Color
Discharge
(RT28)
24 (−4) to 350
(176)
41,000 to 103 1 and 2
(Yellow)
Outdoor
(Ambient)
(RT13)
−35 (−37) to 120
(48)
280,000 to 3750 3 and 4
(Black)
Coil (RT21) −35 (−37) to 120
(48)
280,000 to 3750 5 and 6
(Brown)
NOTE Sensor resistance decreases as sensed temperature
increases (see tables 29 and 30).
W Input Fault or Miswire
In case of a W input fault or possible miswire, the system
will function as listed in the sequence of operation in figure
47.
SECOND−STAGE OPERATION
If the control receives a call for second−stage compressor
operation Y2 in heating or cooling mode and the first-stage
compressor output is active, the second-stage compressor
solenoid output will be energized by the heat pump control
system operation function.
NOTE Figure 36 illustrates the correct Y2 field wiring
configuration.
NOTE The heat pump control system operation monitor
has a five second delay between Y2 being powered and the
solenoid energizing.
Second Stage Lock−in
If first-stage compressor output is active in heating mode
and the outdoor ambient temperature is below the selected
compressor lock−in temperature, the second-stage compressor solenoid output will be energized even without a
Y2 room thermostat input.
If the jumper is not connected to one of the temperature
selection pins (40, 45, 50, 55°F), the default lock−in temperature of 40°F (4.5°C) will be used.
The heat pump control de−energizes the second-stage
compressor solenoid output immediately when the Y2 sig-
nal is removed or the outdoor ambient temperature is 5°F
above the selected compressor lock−in temperature, or the
first-stage compressor output is de−energized for any reason.
Shift Delay
The heat pump control has a field−selectable function to reduce occasional sounds that may occur while the unit is
cycling in and out of the defrost mode. Units are shipped
with jumper installed on pins.
* When the jumper is installed: There is a 30−second
compressor shift delay which de−energizes the compressor contactor output and ECM fan outputs. After
the delay expires, the compressor contactor and ECM
fan outputs are energized.
* When the jumper is not installed: The reversing valve
is changed by de−energizing the outputs immediately.
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XP21
Table 29. Ambient (RT13) and Coil (RT21) Sensors Temperature / Resistance Range
Degrees
Fahrenheit
Resistance
Degrees
Fahrenheit
Resistance
Degrees
Fahrenheit
Resistance
Degrees
Fahrenheit
Resistance
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
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XP21
Table 30. High Discharge Sensor (RT28) Temperature / Resistance Range
Degrees
Fahrenheit
Resistance
Degrees
Fahrenheit
Resistance
Degrees
Fahrenheit
Resistance
Degrees
Fahrenheit
Resistance
303.1 183 186.1 1052 136.8 2656 94.5 6613
298.1 195 185.0 1072 136.0 2698 93.6 6739
293.4 207 183.9 1093 135.2 2740 92.8 6869
289.0 220 182.8 1114 134.5 2783 92.0 7002
284.8 232 181.8 1135 133.7 2827 91.2 7139
280.9 245 180.7 1157 132.9 2872 90.3 7281
277.1 258 179.6 1179 132.2 2917 89.5 7426
273.6 270 178.6 1201 131.4 2963 88.6 7575
270.2 283 177.6 1223 130.6 3010 87.8 7729
267.0 297 176.6 1245 129.9 3057 86.9 7888
263.9 310 175.5 1268 129.1 3105 86.0 8051
260.9 323 174.6 1291 128.4 3154 85.2 8220
258.1 336 173.6 1315 127.6 3204 84.3 8394
255.3 350 172.6 1338 126.8 3255 83.4 8574
252.7 364 171.6 1362 126.1 3307 82.5 8759
250.1 378 170.6 1386 125.3 3359 81.6 8951
247.7 391 169.7 1411 124.6 3413 80.7 9149
245.3 405 168.7 1435 123.8 3467 79.8 9354
243.0 420 167.8 1460 123.1 3523 78.8 9566
240.8 434 166.9 1486 122.3 3579 77.9 9786
238.6 448 165.9 1511 121.6 3637 76.9 10013
236.5 463 165.0 1537 120.8 3695 76.0 10250
234.4 478 164.1 1563 120.1 3755 75.0 10495
232.4 492 163.2 1590 119.3 3816 74.1 10749
230.5 507 162.3 1617 118.5 3877 73.1 11014
228.6 523 161.4 1644 117.8 3940 72.1 11289
226.7 538 160.5 1672 117.0 4005 71.1 11575
224.9 553 159.7 1699 116.3 4070 70.0 11873
223.2 569 158.8 1728 115.5 4137 69.0 12184
221.5 584 157.9 1756 114.8 4205 68.0 12509
219.8 600 157.1 1785 114.0 4274 66.9 12848
218.1 616 156.2 1815 113.2 4345 65.8 13202
216.5 632 155.3 1845 112.5 4418 64.7 13573
214.9 649 154.5 1875 111.7 4491 63.6 13961
213.4 665 153.6 1905 111.0 4567 62.5 14368
211.9 682 152.8 1936 110.2 4644 61.3 14796
210.4 698 152.0 1968 109.4 4722 60.2 15246
208.9 715 151.1 1999 108.7 4802 59.0 15719
207.5 732 150.3 2032 107.9 4884 57.8 16218
206.0 750 149.5 2064 107.1 4968 56.6 16744
204.6 767 148.7 2098 106.4 5054 55.3 17301
203.3 785 147.9 2131 105.6 5141 54.0 17891
201.9 803 147.1 2165 104.8 5231 52.7 18516
200.6 821 146.2 2200 104.0 5323 51.4 19180
199.3 839 145.4 2235 103.3 5416 50.0 19887
198.0 857 144.6 2270 102.5 5512 48.6 20641
196.8 876 143.8 2306 101.7 5610 47.2 21448
195.5 894 143.0 2343 100.9 5711 45.7 22311
194.3 913 142.3 2380 100.1 5814
193.1 932 141.5 2418 99.3 5920
191.9 952 140.7 2456 98.5 6028
190.7 971 139.9 2495 97.7 6139
189.5 991 139.1 2534 96.9 6253
188.4 1011 138.3 2574 96.1 6370
187.2 1031 137.6 2615 95.3 6489
Page 65
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XP21
TOP GRILLE OR FAN MOTOR MOUNT ADJUSTMENT FOR FAN CLEARANCE
Sometimes during shipping, either the fan motor mounting or top grille may become out of alignment. This may cause the fan
motor blade to not clear the orifice ring. If this situation occurs, simply adjust either or both the fan motor mount or top grille
positions to allow proper clearance. The top grille four fastener insertion points to the plastic top and motor mount locations
are larger than the fasteners used to secure the grille and fan motor mounts. Use the procedures provided in figure 32 to
adjust for fan clearance.
GRILLE MOUNTING
POINTS
GRILLE MOUNTING POINTS
FASTENER
INSERTION POINT
FAN MOTOR MOUNTING POINTS
PUSH
FORWARD
PUSH
FORWARD
THE FOUR MOUNTING POINT HOLES THAT SECURE THE TOP
GRILLE TO THE PLASTIC TOP ARE LARGER THAN THE
FASTENERS USED TO SECURE THE GRILLE. THIS IS ALSO TRUE
FOR THE FOUR FASTENERS SECURING THE FAN MOTOR TO THE
TOP GRILLE. TO PROVIDE MORE CLEARANCE, PREFORM EITHER
OR BOTH OF THE FOLLOWING PROCEDURES.
TOP GRILLE ADJUSTMENT
1. LOOSEN THE FOUR GRILLE MOUNTING FASTENERS AND
PUSH THE GRILLE FORWARD. TIGHTEN MOUNTING
HARDWARE. IF THERE IS STILL INSUFFICIENT CLEARANCE
PROCEED TO STEP 2.
FAN MOTOR POSITION ADJUSTMENT
2. LOOSEN THE FOUR FAN MOTOR GRILLE MOUNTING
FASTENERS AND PUSH THE FAN MOTOR FORWARD.
TIGHTEN MOUNTING HARDWARE.
ORIFICE RING
Figure 32. Fan Blade Clearance Adjustment
Page 66
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XP21
CRANKCASE HEATER (HR1)
Compressors in all units are equipped with a 70 watt bellyband type crankcase heater. HR1 prevents liquid from
accumulating in the compressor. HR1 is controlled by the
crankcase heater thermostat.
CRANKCASE HEATER THERMOSTAT (S40)
Thermostat S40 controls the crankcase heater in all units.
S40 is located on the liquid line. When liquid line temperature drops below 50°F the thermostat S40 closes
energizing HR1. The thermostat will open, de−energizing
HR1 once liquid line temperature reaches 70°F .
REVERSING VALVE (L1)
The primary components of the reversing valve are reversing valve, solenoid and wiring harness.
TO COMPRESSOR
DISCHARGE LINE
LINE TO OUTDOOR
COIL
SUCTION LINE (TO
COMPRESSOR)
VAPOR LINE (TO SERVICE VALVE)
SOLENOID
IMPORTANT CONFIRM CORRECT CONNECTIONS OF
REFRIGERANT LINES TO REVERSING VALVE BEFORE
BRAZING IN VALVE.
IMPORTANT ENSURE NEW REVERSING VALVE IS INSTALL EXACTLY AS ORIGINAL
VALVE.
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.
REVERSING VALVE
OPERATION
Figure 33. Typical Reversing Valve Components and Operation
Page 67
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XP21
Maintenance
DEALER
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 pre−lubricated and sealed. No
further lubrication is needed.
3. Visually inspect all connecting lines, joints and coils for
evidence of oil leaks.
4. Check all wiring for loose connections.
5. Check for correct voltage at unit (unit operating).
6. Check amp draw on outdoor fan motor.
Motor Nameplate:_________ Actual:__________.
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.
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 loca-
tions can carry salt, which is corrosive to most metal.
Units that are located near the ocean require frequent
inspections and maintenance. These inspections will
determine the necessary need to wash the unit including the outdoor coil. Consult your installing contractor
for proper intervals/procedures for your geographic
area or service contract.
INDOOR UNIT MAINTENANCE
Indoor Unit
1. Clean or change filters.
2. Lennox blower motors are prelubricated and permanently sealed. No more lubrication is needed.
3. Adjust blower speed for cooling. Measure the pressure
drop over the coil to determine the correct blower CFM.
Refer to the unit information service manual for pressure
drop tables and procedure.
4. Belt Drive Blowers − Check belt for wear and proper
tension.
5. Check all wiring for loose connections.
6. Check for correct voltage at unit. (blower operating)
7. Check amp draw on blower motor.
Motor Nameplate:_________ Actual:__________.
Indoor Coil
1. Clean coil if necessary.
2. Check connecting lines, joints and coil for evidence of
oil leaks.
3. Check condensate line and clean if necessary.
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.
Figure 34. 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
®
Home Energy System.
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).
Page 68
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XP21
Checklists
TWO STAGE COMPRESSOR CHECKOUT
Use this check-out procedure to verify part- and full-load
capacity operation of two-stage modulation compressor.
IMPORTANT
This performance check is ONLY valid on systems that
have clean indoor and outdoor coils, proper airflow over
coils, and correct system refrigerant charge. All
components in the system must be functioning proper to
correctly perform compressor modulation operational
check. (Accurate measurements are critical to this test as
indoor system loading and outdoor ambient can affect
variations between low and high capacity readings).
TOOLS REQUIRED
Refrigeration gauge set
Digital volt/amp meter
Electronic temperature thermometer
On-off toggle switch
PROCEDURE
1. Turn main power OFF to outdoor unit.
2. Adjust room thermostat set point 5ºF above (heating
operation) or 5ºF below (cooling operation) the room
temperature.
3. Remove control access panel. Install refrigeration
gauges on unit. Attach the amp meter to the common
(black wire) wire of the compressor harness. Attach
thermometer to discharge line as close as possible to
the compressor.
4. Turn toggle switch OFF. Install switch in series with Y2
wire from room thermostat (see note ** in the Field Op-
erational Checklist on page 68).
5. Cycle main power ON.
6. Allow pressures and temperatures to stabilize before
taking any measured reading (may take up to 10 minutes).
7. Record all of the readings for the Y1 demand.
8. Close switch to energize Y2 demand. Verify power is
going to compressor solenoid (see note ** in the Field
Operational Checklist on page 68).
9. Allow pressures and temperatures to stabilize before
taking any measured reading (this may take up to 10
minutes).
10. Record all of the readings with the Y1 and Y2 demand.
11. If temperatures and pressures change in the direction
noted in chart, the compressor is properly modulating
from low to high capacity. (If no amperage, pressures
or temperature readings change when this test is performed, the compressor is not switching between low
and high capacity and replacement is necessary).
12. After testing is complete, return unit to original set up.
XP21 Field Operational Checklist
Unit Readings
Cooling*** Heating***
Y1
First
Stage
Expected results
during Y2 demand
(Toggle switch On)
Y2
Second
Stage
Y1
First Stage
Expected results
during Y2 demand
(Toggle switch On)
Y2 Second
Stage
Compressor
Voltage Same Same
Amperage Higher Higher
Condenser Fan motor
Amperage Same or Higher Same or Higher
Temperature
Ambient Same Same
Outdoor Coil Discharge Air Higher Lower
Compressor Discharge Line Higher Higher
Indoor Return Air Same Same
Indoor Coil Discharge Air Lower Higher
Pressures
Suction (Vapor) Lower Down
Liquid Higher Higher
Note − Heat pump may have a low ambient control or Control that locks in second−stage below its set point. It may be necessary to remove a wire
from the control when performing this check out.
** On the XP21 units, the System Operation Monitor controls the second−stage solenoid coil in compressor.
*** Cooling Mode Operation − Block outdoor coil to maintain a minimum of 375 psig during testing.
Heating Mode Operation − Block indoor coil to maintain a minimum of 375 psig during testing.
Page 69
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XP21
Unit Wiring Diagrams
The following wiring diagrams were used during various stages of unit production. Service technician will need to visually
inspect the unit being service to determine which wiring diagram is applicable. Quick verification can usually be made by
comparing the wiring diagram located on the unit access panel to the following diagrams.
Figure 35. Typical XP21 Wiring (XP21−XXX−230−01 only)
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XP21
Figure 36. Typical XP21 Wiring (XP21−024−230−02, −03 and −04, XP21−036−230−02 and −03, XP21−048−230−02 and
−03, XP21−060−230−02 and −03)
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XP21
Figure 37. Typical XP21 Wiring (XP21−024−230−05, XP21−036−230−04, XP21−048−230−04 and XP21−060−230−04)
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XP21
Factory Wiring Diagrams
Figure 38. Typical Factory Wiring (XP21−XX−230−01)
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XP21
Figure 39. Typical Factory Wiring (XP21−024−230−02, −03 and −04, XP21−036−230−02 and −03, XP21−048−230−02 and
−03, XP21−060−230−02 and −03)
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XP21
Figure 40. Typical Factory Wiring (XP21−024−230−05, XP21−036−230−04, XP21−048−230−04, XP21−060−230−04)
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XP21
Unit Sequence of Operations
The following figures illustrated the overall unit sequence of operations along with various pressure switches and temperature sensor operations. The figures also illustration the use of the compressor anti−short cycle function in relations to unit
Status, Fault and Lockout LED Codes system operations interaction.
On 24VAC power−up or heat pump control (A175) reset, the heat pump control shall perform the
following tasks:
1. Start the anti−short cycle delay.
2. Check temperature sensor and pressure switches at the start of cooling demand.
3. Heat pump control responds to the thermostat input after the anti−short cycle timer expires. If there is
no thermostat input, control goes to standby mode.
Heat Pump control receives
cooling input.
The heat pump control (A175) will apply:
1. 24VAC to compressor contactor output Y1 OUT..
2. 24VAC to reversing valve output O terminal.
3. Output between 24 and 32 VDC on heat pump control’s
ECM fan terminals ECM Y1 FAN and ECM C.
NOTE − If low pressure switch is closed, system will ignore for
90 seconds.
The outdoor fan control (A177) will:
Receive the DC voltage signal from the outdoor control (A175) and
converted the signal to a pulse width modulation (PWM) signal. Jumper
settings will determine fan PWM OUT fan speed.
NOTE Refer to 17 for jumper settings.
1. For low (S87) and high (S4) pressure switches sequence of
operations, see figures 43 and 44.
2. For temperature switch RT28 sequence of operations, see
figure 45.
3. For Defrost calibration sequence of operations see figure 46.
4. For Defrost sequence of operations see figure 46.
Room thermostat calls for high (two−stage)
The heat pump control will apply::
1. 24VAC to second−stage solenoid output that will energized after the
first−stage compressor has been active for a minimum of five (5)
seconds.
2. Output between 24 and 32 VDC on heat pump control’s
second−stage ECM fan terminals ECM Y2 AND ECM C.
The outdoor fan control (A177) will:
Receive the DC voltage signal from the outdoor control (A175)
and converted the signal to a pulse width modulation (PWM)
signal. Jumper settings will determine fan PWM OUT fan speed.
NOTE Refer to table 17 for jumper settings.
Two−stage Ambient Lock−in Temperature
Should the ambient temperature be below the selected two−stage lock−in
temperature (jumper in place on jumper pin strip) , the two−stage solenoid
output will be energized after the one−stage minimum run timer expires
Energize two−stage ECM fan outputs ECM Y2 Fan and Y2 input/output.
Appropriate system status LED code is displayed to indicate two−stage heat
lock−in.
Room thermostat
calls for low (one−
stage)
Heat Pump control receives
heating input.
The heat pump control (A175) will apply:
1. 24VAC to compressor contactor output Y1 OUT..
2. Output between 24 and 32 VDC on heat pump
control’s ECM fan terminals ECM Y1 FAN and
ECM C.
NOTE − If low pressure switch is closed, system will
ignore for 90 seconds.
Figure 41. One− and Two−Stage Cooling Sequence of Operations (101796−XX Only)
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XP21
On 24VAC power−up or heat pump control (A175) reset, the heat pump control shall perform the following tasks:
1. Start the anti−short cycle delay.
2. Check temperature sensor and pressure switches at the start of demand.
3. Heat pump control responds to the thermostat input after the anti−short cycle timer expires. If there is no thermostat input, control goes to
standby mode.
Heat Pump control receives
cooling input.
The heat pump control (A175) will apply:
1. 24VAC to compressor contactor output Y1 OUT..
2. 24VAC to reversing valve output O terminal.
3. A field programmed RPM (DC voltage that represents
an RPM output value) is applied to the FAN PWM and
COM terminals.(The control’s 7 segment will display the
field programmed RPM of the outdoor fan motor)
NOTE − If low pressure switch is closed, system will ignore for
90 seconds.
1. For low (S87) and high (S4) pressure switches sequence of
operations, see figures 43 and 44.
2. For temperature switch RT28 sequence of operations, see
figure 45.
3. For Defrost calibration sequence of operations see figure 46.
4. For Defrost sequence of operations see figure 46.
Room thermostat calls for high (two−stage)
The heat pump control will apply::
1. 24VAC to second−stage solenoid output that will energized after the first−stage compressor has been active for a minimum of five (5)
seconds.
2. A field programmed RPM (DC voltage that represents an RPM output value) is applied to the FAN PWM and COM terminals. (The
control’s 7 segment will display the field programmed RPM of the outdoor fan motor)
The outdoor fan motor (B4) receive the (PWM) Pulse Width
Modulation DC volt signal from the control and runs the fan motor
at the field programmed RPM speed.
Two−stage Ambient Lock−in Temperature
Should the ambient temperature be below the selected two−stage lock−in
temperature (jumper in place on jumper pin strip) , the two−stage solenoid
output will be energized, after the 1st stage 5 second delay expires, the
outdoor fan will go to high stage and a Y2 signal will be output to the indoor
unit to cycle the indoor fan to high speed.
Room thermostat
calls for low (one−
stage)
Heat Pump control receives
heating input.
The heat pump control (A175) will apply:
1. 24VAC to compressor contactor output Y1 OUT..
2. A field programmed RPM (DC voltage that represents an
RPM output value) is applied to the FAN PWM and COM
terminals.(The control’s 7 segment will display the field
programmed RPM of the outdoor fan motor)
NOTE − If low pressure switch is closed, system will ignore for 90
seconds.
The outdoor fan motor (B4) receive the (PWM) Pulse Width
Modulation DC volt signal from the control and runs the fan motor
at the field programmed RPM speed.
Figure 42. One− and Two−Stage Cooling Sequence of Operations (103369−01 Only)
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XP21
Y1 DEMAND
LOW
PRESSURE
SWITCH (S87)
COMPRESSOR
CONTACTOR
ENERGIZED
INITIAL TRIP
SWITCH IS
IGNORED FOR
90 SECONDS
LOW
PRESSURE
SWITCH (S87)
COMPRESSOR
CONTACTOR
DE−ENERGIZED
COMPRESSOR
ANTI−SHORT
CYCLE TIMER
BEGINS
INCREMENT
5−STRIKE
COUNTER
1
LED ALERT
CODE / OR
MODERATE
ALERT 410
DISPLAYED
ANTI−SHORT
CYCLE TIMER
ENDS
COMPRESSOR
CONTACTOR
ENERGIZED
LOW
PRESSURE
SWITCH (S87)
WAITING FOR
PRESSURE
SWITCH TO
CLOSE
SWITCH IS CLOSED OR OUTDOOR
AMBIENT TEMPERATURE IS 15ºF
OR BELOW
5−STRIKE
COUNTER
REACHES 5
WITHIN A SINGLE
Y1 DEMAND
LOW
PRESSURE
SWITCH (S87)
LOCKOUT
LED ALERT
CODE / OR
CRITICAL
ALERT 411
DISPLAYED
SERVICE
REQUIRED
2
LED ALERT
CODE / OR
MODERATE
ALERT 410
DISPLAYED
SERVICE
REQUIRED
2
NORMAL
OPERATION
CLOSED
CLOSED
OPEN
OPEN
1
If 5−strike counter has four or less strikes when Y1 demand
is terminated or satisfied, the strike counter will reset to
zero. In a icomfort setup, the thermostat will terminate
demand when the compressor contactor is de−energized. If
demand is satisfied when alarm is not active, the 5−strike
counter will reset.
2
Lockouts can be reset by either cycling power off to the
heat pump control’s (A175) R terminal, or placing a jumper
on the field test pins (E33) between 1 to 2 seconds.
OPEN
CLOSED
CLOSED
Figure 43. Low Pressure Switch (S87) Sequence of Operation (All Versions)
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XP21
Y1 DEMAND
HIGH
PRESSURE
SWITCH (S4)
COMPRESSOR
CONTACTOR
ENERGIZED
HIGH
PRESSURE
SWITCH (S4)
COMPRESSOR
CONTACTOR
DE−ENERGIZED
COMPRESSOR
ANTI−SHORT
CYCLE TIMER
BEGINS
INCREMENT
5−STRIKE
COUNTER
1
LED ALERT
CODE / OR
MODERATE
ALERT 412
DISPLAYED
ANTI−SHORT
CYCLE TIMER
ENDS
COMPRESSOR
CONTACTOR
ENERGIZED
HIGH
PRESSURE
SWITCH (S4)
WAITING FOR
PRESSURE
SWITCH TO
CLOSE
5−STRIKE
COUNTER
REACHES 5
WITHIN A SINGLE
Y1 DEMAND
HIGH
PRESSURE
SWITCH (S4)
LOCKOUT
LED ALERT
CODE / OR
CRITICAL
ALERT 413
CLEARED
SERVICE
REQUIRED
2
LED ALERT
CODE / OR
MODERATE
ALERT 412
DISPLAYED
SERVICE
REQUIRED
2
NORMAL
OPERATION
CLOSED
CLOSED
OPEN
OPEN
1
If 5−strike counter has four or less strikes when Y1 demand
is terminated or satisfied, the strike counter will reset to
zero. In a icomfort
setup, the thermostat will terminate
demand when the compressor contactor is de−energized. If
demand is satisfied when alarm is not active, the 5−strike
counter will reset.
2
Lockouts can be reset by either cycling power off to the
heat pump control’s (A175) R terminal, or placing a jumper
on the field test pins (E33) between 1 to 2 seconds.
OPEN
CLOSED
CLOSED
Figure 44. High Pressure Switch (S4) Sequence of Operation (All Versions)
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XP21
Y1 DEMAND
DISCHARGE
SENSOR
(RT28)*
COMPRESSOR
CONTACTOR
ENERGIZED
HIGH
PRESSURE
SWITCH (S4)
COMPRESSOR
CONTACTOR
DE−ENERGIZED
COMPRESSOR
ANTI−SHORT
CYCLE TIMER
BEGINS
INCREMENT
5−STRIKE
COUNTER
1
LED ALERT
CODE / OR
MODERATE
ALERT 414
DISPLAYED
ANTI−SHORT
CYCLE TIMER
ENDS
COMPRESSOR
CONTACTOR
ENERGIZED
DISCHARGE
SENSOR (RT28)
IS AT OR
BELOW 225ºF
WAITING FOR
TEMPERATURE
DROP TO OR
BELOW 225ºF
5−STRIKE
COUNTER
REACHES 5
WITHIN A SINGLE
Y1 DEMAND
DISCHARGE
SENSOR (RT28)
LOCKOUT
LED ALERT
CODE / OR
CRITICAL
ALERT 415
CLEARED
SERVICE
REQUIRED
2
LED ALERT
CODE / OR
MODERATE
ALERT 414
CLEARED
NORMAL
OPERATION
CLOSED
CLOSED
OPEN
OPEN
1
If 5−strike counter has four or less strikes when Y1 demand
is terminated or satisfied, the strike counter will reset to
zero. In a icomfort setup, the thermostat will terminate
demand when the compressor contactor is de−energized. If
demand is satisfied when alarm is not active, the 5−strike
counter will reset.
2
Lockouts can be reset by either cycling power off to the
heat pump control’s (A175) R terminal, or placing a jumper
on the field test pins (E33) between 1 to 2 seconds.
NO
*
If temperature is at or above 279ºF.
YES
Figure 45. High Discharge Temperature Sensor (RT28) Sequence of Operation (All Versions)
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XP21
Continue to
accumulate
run time.
Heat pump control monitors mode of
operation through outdoor ambient
temperature (RT13), outdoor coil
temperature (RT21) and compressor
run−time to determine when a defrost
cycle is required.
Defrost Calibration
Defrost Mode
Coil temperature sensor input
(RT21) reached specified defrost termination temperature
as set on heat pump control
E47 pins*.
Calibration Attempted
(Unit Running in Heat
Mode)
Calibration
Demand Mode
After the initial calibration, the heat pump control disables the defrost mode for 30−34 minutes in order to avoid unnecessary defrosts.
Beyond this timing period, both the ambient
(RT13) and coil (RT21) sensors are continuously monitored. If the coil temperature is below 35°F (2°C) and the calibration delta is
reached or accumulated compressor run−time
is more than six (6) hours, a defrost is to be initiated.
100
90
DEGREE
TARGET
70
DEGREE
TARGET
*50
DEGREE
TARGET
100
90
70
50
DEGREE
TARGET
100
90
70
50
100
90
70
50
100
90
70
50
E47
*Heat Pump Control (A175)
Defrost Termination (E47)
Pins (Factory Default is 50ºF)
Coil sensor
below 35°F {2°C}
No attempt
to calibrate.
30−35 minutes
compressor
run−time
Accumulate compressor run−time while outdoor
coil temperature sensor input (RT21) is below
35°F (2°C)
Defrosted for 14 minutes without the coil temperature sensor
input (RT21) reaching defrost
termination temperature as set
on heat pump control E47
pins*.
How did defrost
terminate?
NO
NO
YES
YES
NO
Coil sensor (RT21) detects temperature below 35°F {2°C}
during either initial power−up, after loss of power or after
cooling mode, a sacrificial defrost will be used to ensure there
is a clear coil before attempting calibration.
Initiate a defrost and monitor coil temperature
sensor input (RT21) and accumulate defrost time.
YES
NOTE No system alert codes can
be active for defrost calibration to be
achieved.
Figure 46. Defrost Calibration and Defrost Mode Sequence of Operations (All Versions)
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XP21
Y1 DEMAND
COMPRESSOR
CONTACTOR
ENERGIZED
INITIAL TRIP
SWITCH IS
IGNORED FOR
90 SECONDS
W OUTPUT
ACTIVE)
COMPRESSOR
CONTACTOR
DE−ENERGIZED
COMPRESSOR
ANTI−SHORT
CYCLE TIMER
BEGINS
INCREMENT
5−STRIKE
COUNTER
1
LED ALERT
CODE / OR
MODERATE
ALERT 418
DISPLAYED
ANTI−SHORT
CYCLE TIMER
ENDS
W OUTPUT
HARDWARE
FAULT
LOCKOUT
WAITING FOR
W OUTPUT TO
DEACTIVATE
5−STRIKE
COUNTER
REACHES 5
WITHIN A SINGLE
Y1 DEMAND
LED ALERT
CODE / OR
MODERATE
ALERT 418
DISPLAYED
LED ALERT
CODE / OR
CRITICAL
ALERT 419
DISPLAYED
SERVICE
REQUIRED
2
YES
W OUTPUT
ACTIVE)
NO
COMPRESSOR
ANTI−SHORT
CYCLE TIMER
BEGINS
YES
LED ALERT
CODE / OR
MODERATE
ALERT 418
CLEARED
ANTI−SHORT
CYCLE TIMER
ENDS
W OUTPUT
ACTIVE)
NORMAL
OPERATION
LED ALERT
CODE / OR
MODERATE
ALERT 418
CLEARED
NO
YES
NO
1
If 5−strike counter has four or less strikes when Y1 demand is terminated or satisfied,
the strike counter will reset to zero. In a comfort
®
enabled setup, the thermostat will
terminate demand when the compressor contactor is de−energized. If demand is
satisfied when alarm is not active, the 5−strike counter will reset.
2
Lockouts can be reset by either cycling power off to the heat pump control’s (A175)
R terminal, or placing a jumper on the field test pins (E33) between 1 to 2 seconds.
Figure 47. W Input Fault or Miswire Sequence of Operation (All Versions)
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