Lenox Air Conditioner Elite Series XP16 Units Heat Pumps User Manual

INSTALLATION  
INSTRUCTIONS  
E20 Lennox Industries Inc.  
Dallas, Texas, USA  
Elite® Series XP16 Units  
HEAT PUMPS  
506640−01  
12/10  
These instructions are intended as a  
Litho U.S.A.  
general guide and do not supersede  
local codes in any way. Consult  
authorities having jurisdiction before  
installation.  
Supersedes 11/10  
TABLE OF CONTENTS  
Shipping and Packing List . . . . . . . . . . . . . . . . . . . . . .  
Model Number Identification . . . . . . . . . . . . . . . . . . . .  
Typical Parts Arrangement . . . . . . . . . . . . . . . . . . . . . .  
Caps and Fasteners Torque Requirements . . . . . . . .  
Operating Gauge Set and Service Valves . . . . . . . . .  
Recovering Refrigerant from Existing System . . . . .  
New Outdoor Unit Placement . . . . . . . . . . . . . . . . . . .  
Removing and Installing Panels . . . . . . . . . . . . . . . . .  
Line Set Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  
RETAIN THESE INSTRUCTIONS FOR FUTURE  
REFERENCE  
NOTICE TO INSTALLER  
BRAZING LINE SET TO SERVICE VALVES  
It is imperative to follow the brazing technique illustrated starting on  
page 11 to avoid damaging the service valve’s internal seals.  
Indoor Refrigerant Metering Device Removal and  
Flushing Line Set and Indoor Coil . . . . . . . . . . . . . . . . 14  
WARNING  
Improper installation, adjustment, alteration, service or  
maintenance can cause personal injury, loss of life, or  
damage to property.  
Installing New Indoor Metering Device . . . . . . . . . . . . 15  
Leak Test Line Set and Indoor Coil . . . . . . . . . . . . . . . 16  
Evacuating Line Set and Indoor Coil . . . . . . . . . . . . . 17  
Installation and service must be performed by a licensed  
professional installer (or equivalent) or a service agency.  
Servicing and Weighing In Refrigerant for Units  
IMPORTANT  
Optimizing System Refrigerant Charge . . . . . . . . . . . 26  
Two−Stage Modulation Compressors Checks . . . . . . 40  
The Clean Air Act of 1990 bans the intentional venting of  
refrigerant (CFCs, HFCs, and HCFCs) as of July 1,  
1992. Approved methods of recovery, recycling or  
reclaiming must be followed. Fines and/or incarceration  
may be levied for noncompliance.  
Shipping and Packing List  
IMPORTANT  
This unit must be matched with an indoor coil as  
specified in Lennox XP16 Engineering Handbook.  
Coils previously charged with HCFC−22 must be  
flushed.  
Check unit for shipping damage. Consult last carrier  
immediately if damage is found.  
1 − Assembled outdoor unit  
General  
The XP16 outdoor unit uses HFC−410A refrigerant. This  
unit must be installed with a matching indoor blower coil  
and line set as outlined in the XP16 Lennox Engineering  
Handbook. Elite® Series outdoor units are designed for  
use in check / expansion valve (CTXV) systems only and  
are not to be used with other refrigerant flow control  
devices. An indoor coil check / expansion valve approved  
for use with HFC−410A must be ordered separately and  
installed prior to operating the unit.  
CAUTION  
Physical contact with metal edges and corners while  
applying excessive force or rapid motion can result in  
personal injury. Be aware of, and use caution when  
working near these areas during installation or while  
servicing this equipment.  
12/10  
506640−01  
Page 1  
*2P1210*  
*P506640-01*  
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Typical Unit Parts Arrangement  
FOR COIL SENSOR (RT21)  
LOCATION SEE DETAIL A  
COMPRESSOR  
DUAL RUN CAPACITOR (C12)  
(−024, −036 AND −048 ONLY)  
SINGLE RUN CAPACITOR (C1)  
(−060 ONLY)  
DEMAND DEFROST  
CONTROL (A108)  
DISCHARGE LINE  
SENSOR (RT28)  
REVERSING  
VALVE (L1)  
TRUE SUCTION  
PORT  
HIGH PRESSURE  
SWITCH (S4)  
EXPANSION VALVE  
SENSING BULB  
CHECK /  
EXPANSION  
VALVE  
LIQUID VALVE AND GAUGE  
PORT / LIQUID LINE  
CONNECTIONS  
LIQUID LINE  
BI−FLOW FILTER  
DRIER  
GROUND  
LUG  
LOW PRESSURE  
SWITCH (S87)  
SINGLE POLE  
CONTACTOR  
(K1)  
AMBIENT  
TEMPERATURE  
SENSOR (RT13)  
VAPOR VALVE AND GAUGE PORT /  
SUCTION LINE CONNECTIONS  
DETAIL A  
XP16−048  
COIL SENSOR − EIGHT HAIRPIN  
UP FROM THE BOTTOM ON  
INSIDE ROW.  
XP16−036  
XP16−060  
COIL SENSOR −  
SIXTH HAIRPIN UP  
FROM THE BOTTOM  
COIL SENSOR − NINTH  
HAIRPIN UP FROM THE  
BOTTOM ON INSIDE  
ROW.  
ON INSIDE ROW.  
XP16−024  
COIL SENSOR −THIRD  
HAIRPIN DOWN FROM  
THE TOP ON INSIDE  
ROW.  
Figure 1. Unit Parts Arrangement  
Caps and Fasteners Torque Requirements  
When servicing or repairing HVAC equipment and  
components, ensure the fasteners are appropriately  
fasteners.  
IMPORTANT  
Only use Allen wrenches of sufficient hardness (50Rc −  
Rockwell Harness Scale minimum). Fully insert the  
wrench into the valve stem recess.  
Table 1. Torque Requirements  
Parts  
Recommended Torque  
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.  
Service valve cap  
Sheet metal screws  
Machine screws #10  
Compressor bolts  
Gauge port seal cap  
8 ft.− lb.  
11 NM  
2 NM  
16 in.− lb.  
28 in.− lb.  
90 in.− lb.  
8 ft.− lb.  
3 NM  
10 NM  
11 NM  
See the Lennox Service and Application Notes  
Corp.0807−L5 (C−08−1) for further details and  
information.  
Page 3  
XP16 SERIES  
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Operating Gauge Set and Service Valves  
USING MANIFOLD GAUGE SET  
IMPORTANT  
To prevent stripping of the various caps used, the  
appropriately sized wrench should be used and fitted  
snugly over the cap before tightening.  
When checking the system charge, only use a manifold  
gauge set that features low−loss anti−blow back fittings.  
Manifold gauge set used for HFC−410A refrigerant  
systems must be capable of handling the higher system  
operating pressures. The manifold gauges should be rated  
for:  
OPERATING SERVICE VALVES  
The liquid and vapor line service valves are used for  
refrigerant recovery, flushing, leak testing, evacuating,  
weighing in refrigerant and optimizing system charge.  
S
S
S
High side ꢀ Pressure range of 0 − 800 pound−force per  
square inch gauge (psig)  
Low side ꢀ Use with 30" vacuum to 250 psig with  
dampened speed to 500 psig  
Each valve is equipped with a service port which has a  
factory−installed valve core. Figure 2 provides information  
on how to access and operate both angle− and ball−type  
service valves.  
Manifold gauge set hoses must be rated for use to 800  
psig of pressure with a 4000 psig burst rating.  
Operating Angle−Type Service Valve:  
1. Remove stem cap with an appropriately sized wrench.  
INSERT HEX−HEAD  
EXTENSION HERE  
2
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 to open  
the service valve.  
SERVICE PORT CAP  
TO INDOOR  
UNIT  
SERVICE PORT CORE  
TO OUTDOOR  
UNIT  
SERVICE PORT  
CORE  
(VALVE STEM SHOWN OPEN)  
INSERT HEX WRENCH HERE  
VALVE STEM  
SHOWN  
CLOSED  
TO INDOOR  
UNIT  
REMOVE  
STEM CAP  
1
When service valve stem is in the CLOSED position,  
the service port is open to the line set and indoor unit.  
STEM CAP  
TO OUTDOOR UNIT  
To Access Service Port:  
When service valve is OPEN, the service port is open to line set,  
indoor and outdoor unit.  
1/6 TURN  
A service port cap protects the service port core from  
contaminationand serves as the primary leak seal.  
Operating Ball−Type Service Valve:  
12  
6
1
5
11  
10  
1. Remove service port cap with an appropriately sized  
wrench.  
2
1. Remove stem cap with an appropriately sized wrench.  
2. Use an appropriately sized wrenched to open.  
9
3
2. Connect gauge set to service port.  
4
8
7
A
To open rotate stem  
counterclockwise  
90°.  
3. When testing is completed, replace service port cap and  
tighten as follows:  
TO INDOOR UNIT  
S
With torque wrench: Finger tighten and torque cap per table 1.  
B
To close rotate stem  
clockwise 90°.  
S
Reinstall Stem Cap:  
Without torque wrench: Finger tighten and use an appropriately sized  
wrench to turn an additional 1/6 turn clockwise.  
1/12 TURN  
BALL (SHOWN CLOSED)  
VALVE STEM  
2
Stem cap protects the valve stem from damage and  
serves as the primary seal. Replace the stem cap and  
tighten as follows:  
12  
1
5
11  
10  
SERVICE PORT  
2
SERVICE PORT CORE  
SERVICE PORT CAP  
9
3
S
S
With Torque Wrench: Finger tighten and then  
torque cap per table 1.  
4
8
7
6
Without Torque Wrench: Finger tighten and use an  
REMOVE  
STEM CAP  
TO OUTDOOR UNIT  
appropriatelysized wrench to turn an additional 1/12 turn clockwise.  
1
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−Type Service Valves  
Page 4  
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Recovering Refrigerant from Existing System  
CONNECT MANIFOLD GAUGE SET  
DISCONNECT POWER  
Connect a manifold gauge set, clean recovery cylinder and a  
recovery machine to the service ports of the existing unit..  
Disconnect all power to the existing outdoor unit at the disconnect  
switch and/or main fuse box/breaker panel.  
2
1
NOTE ꢀ Use the recovery machine instructions to make  
the correct manifold gauge set connections for recovery  
refrigerant.The illustration below is a typical connection.  
MAIN FUSE  
BOX/BREAKER  
PANEL  
MANIFOLD GAUGES  
DISCONNECT  
SWITCH  
RECOVERY MACHINE  
LOW  
HIGH  
OUTDOOR UNIT  
CLEAN RECOVERY  
CYLINDER  
RECOVERING REFRIGERANT  
3
Remove existing HCFC−22 refrigerant using one of the following procedures:  
METHOD 2 LIMITATIONS  
METHOD 1:  
Use Method 1 if the existing outdoor unit is not equipped with shut−off valves, or  
if the unit is not operational and you plan to use the existing HCFC−22 to flush  
the system.  
NOTE ꢀ When using Method 2, the listed devices  
below could prevent full system charge recovery into  
the outdoor unit:  
Recover all HCFC−22 refrigerant from the existing system using a recovery  
machine and clean recovery cylinder. Check gauges after shutdown to confirm  
that the entire system is completely void of refrigerant.  
S
Outdoor unit’s high or low−pressure switches (if  
applicable) when tripped can cycle the  
compressor OFF.  
S
S
Compressor can stop pumping due to tripped  
internal pressure relief valve.  
METHOD 2:  
Use Method 2 if the existing outdoor unit is equipped with manual shut−off valves,  
and you plan to use new HCFC−22 refrigerant to flush the system.  
Compressor has internal vacuum protection that  
is designed to unload the scrolls (compressor  
stops pumping) when the pressure ratio meets a  
certain value or when the suction pressure is as  
high as 20 psig. (Compressor suction  
pressuresshould never be allowed to go into  
a vacuum. Prolonged operation at low suction  
pressures will result in overheating of the  
scrolls and permanent damage to the scroll  
tips, drive bearings and internal seals.)  
Perform the following task:  
A
Start the existing HCFC−22 system in the cooling mode and close the liquid line  
valve.  
B
Use the compressor to pump as much of the existing HCFC−22 refrigerant into  
the outdoor unit until the outdoor system is full. Turn the outdoor unit main power  
OFF and use a recovery machine to remove the remaining refrigerant from the  
system.  
NOTE ꢀ It may be necessary to bypass the low pressure switches (if equipped) to  
ensure complete refrigerant evacuation.  
Once the compressor can not pump down to a lower  
pressure due to any of the above mentioned system  
conditions, shut off the vapor valve. Turn OFF the main  
power to unit and use a recovery machine to recover  
any refrigerant left in the indoor coil and line set.  
C
D
When the low side system pressures reach 0 psig, close the vapor line valve.  
Check gauges after shutdown to confirm that the valves are not allowing  
refrigerantto flow back into the low side of the system.  
Figure 3. Refrigerant Recovery  
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.  
WARNING  
Refrigerant can be harmful if it is inhaled. Refrigerant must be used and recovered responsibly.  
Failure to follow this warning may result in personal injury or death.  
Page 5  
XP16 SERIES  
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New Outdoor Unit Placement  
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.  
CAUTION  
In order to avoid injury, take proper precaution when lift-  
ing heavy objects.  
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.  
Remove existing outdoor unit prior to placement of new  
outdoor unit. See Unit Dimensions on page 2 for sizing  
mounting slab, platforms or supports. Refer to figure 4 for  
mandatory installation clearance requirements.  
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.  
POSITIONING CONSIDERATIONS  
Consider the following when positioning the unit:  
S
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.  
ROOF MOUNTING  
Install the unit a minimum of 6 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. See figure 5, detail F for other roof top  
mounting considerations.  
S
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.  
NOTICE  
Roof Damage!  
This system contains both refrigerant and oil. Some  
rubber roofing material may absorb oil and cause the  
rubber to swell when it comes into contact with oil. The  
rubber will then bubble and could cause leaks. Protect  
the roof surface to avoid exposure to refrigerant and oil  
during service and installation. Failure to follow this  
notice could result in damage to roof surface.  
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  
MINIMUM CLEARANCE  
ABOVE UNIT  
CLEARANCE ON ALL SIDES ꢀ INCHES (MILLIMETERS)  
6 (152)  
ACCESS PANEL  
NOTES:  
S
S
Clearance to one of the other three  
sides must be 36 inches (914mm).  
30 (762)  
48 (1219)  
12 (305)  
Clearance to one of the remaining  
two sides may be 12 inches  
(305mm) and the final side may be  
6 inches (152mm).  
LINE SET  
CONNECTIONS  
36 (914)  
MINIMUM CLEARANCE BETWEEN TWO UNITS  
24  
(610)  
Figure 4. Installation Clearances  
Page 6  
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ꢀ Outside Unit Placement  
DETAIL A  
Install unit away from windows.  
ꢀ Slab Mounting at Ground Level  
DETAIL B  
Install unit level or, if on a slope, maintain slope tolerance of two (2)  
degrees (or two inches per five feet [50 mm per 1.5 m]) away from  
building structure.  
BUILDING  
STRUCTURE  
MOUNTING  
SLAB  
GROUND LEVEL  
TWO 90° ELBOWS INSTALLED IN LINE SET WILL  
REDUCE LINE SET VIBRATION.  
Elevated Slab Mounting  
DETAIL C ꢀ  
ꢀ Slab Side Mounting  
DETAIL D  
using Feet Extenders  
#10 1/2" LONG SELF−DRILLING  
SHEET METAL SCREWS  
COIL  
STABILIZING BRACKET (18 GAUGE  
METAL ꢀ 2" WIDTH; HEIGHT AS  
REQUIRED)  
BASE PAN  
#10 1−1/4" LONG HEX HD SCREW  
AND FLAT WASHER  
CORNER POST  
Concrete slab ꢀ use two plastic anchors (hole  
drill 1/4")  
BASE  
Wood or plastic slab ꢀ no plastic anchor (hole  
drill 1/8")  
Stabilizing bracket (18 gauge metal ꢀ 2" (50.8mm) width; height as required); bend to form  
right angle as exampled below.  
LEG DETAIL  
2" (50.8MM) SCH 40  
FEMALE THREADED  
ADAPTER  
ꢀ Roof Top Mounting  
DETAIL F  
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 as illustrated.  
2" (50.8MM) SCH 40  
MALE THREADED  
ADAPTER  
PREVAILING WINTER WINDS  
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.  
WIND BARRIER  
INLET AIR  
ꢀ Deck Top Mounting  
DETAIL E  
MINIMUM ONE  
PER SIDE  
One bracket per side  
(minimum). For extra  
INLET AIR  
INLET AIR  
stability, two brackets per  
side, two inches (51mm)  
from each corner.  
SAME FASTENERS AS  
SLAB SIDE MOUNTING.  
FOR EXTRA  
STABILITY  
INLET AIR  
Figure 5. Placement, Slab Mounting and Stabilizing Unit  
Page 7  
XP16 SERIES  
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Removing and Installing Panels  
LOUVERED PANEL REMOVAL  
Remove the louvered panels as follows:  
IMPORTANT! DO NOT ALLOW PANELS TO HANG ON UNIT BY TOP TAB. TAB IS FOR  
ALIGNMENT AND NOT DESIGNED TO SUPPORT WEIGHT OF PANEL.  
1. Remove two screws, allowing the panel to swing open  
slightly.  
PANEL SHOWN SLIGHTLY ROTATED TO ALLOW TOP TAB TO EXIT (OR  
ENTER) TOP SLOT FOR REMOVING (OR INSTALLING) PANEL.  
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.  
SCREW  
HOLES  
3. Move panel down until lip of upper tab clears the top slot in  
corner post as illustrated in detail A.  
LIP  
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:  
Detail A  
Detail B  
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.  
ROTATE IN THIS DIRECTION;  
THEN DOWN TO REMOVE  
PANEL  
HOLD DOOR FIRMLY TO THE HINGED  
SIDE TO MAINTAIN  
FULLY−ENGAGED TABS  
ANGLE MAY BE TOO  
EXTREME  
Detail C  
PREFERRED ANGLE  
FOR INSTALLATION  
Detail D  
MAINTAIN MINIMUM PANEL ANGLE (AS CLOSE TO  
PARALLEL WITH THE UNIT AS POSSIBLE) WHILE  
INSTALLING PANEL.  
Figure 6. Removing and Installing Panels  
WARNING  
To prevent personal injury, or damage to panels, unit or structure, be sure to observe the following:  
While installing or servicing this unit, carefully stow all removed panels out of the way, so that the panels will not cause  
injury to personnel, nor cause damage to objects or structures nearby, nor will the panels be subjected to damage (e.g.,  
being bent or scratched).  
While handling or stowing the panels, consider any weather conditions, especially windy conditions, that may cause  
panels to be blown around and battered.  
Page 8  
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Line Set Requirements  
This section provides information on: installation of new or  
replacement line set.  
S
S
Model (XP16) 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.  
S
S
S
Adding Polyol ester oil requirements  
New or replacement line set installation  
Using existing line set.  
S
Number of elbows vertical rise or drop in the piping.  
USING EXISTING LINE SET  
ADDING POLYOL ESTER OIL REQUIREMENTS  
Things to consider:  
S
S
S
Liquid line that meter the refrigerant, such as RFC1  
liquid line, must not be used in this application.  
IMPORTANT  
Mineral oils are not compatible with HFC−410A. If oil  
must be added, it must be a Polyol Ester oil.  
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 Line Set and Indoor Coil on page 14).  
The compressor is charged with sufficient Polyol Ester oil  
(POE) for line set lengths up to 50 feet. Recommend  
adding oil to system based on the amount of refrigerant  
charge in the system. Systems with 20 pounds or less of  
refrigerant required no oil to be added.  
If existing line set is being used, then proceed to Brazing  
Connections on page 11.  
For systems over 20 pounds − add one ounce for every five  
(5) pounds of HFC−410A refrigerant.  
IMPORTANT  
Recommended topping−off POE oils are Mobil EAL  
ARCTIC 22 CC or ICI EMKARATEt RL32CF.  
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 Line Set and Indoor Coil on page  
13.  
NEW OR REPLACEMENT LINE SET INSTALLATION  
Field refrigerant piping consists of both liquid and vapor  
lines from the outdoor unit to the indoor coil. Use Lennox  
L15 (sweat, non−flare) series line set, or field−fabricated  
refrigerant line sizes as specified in table 2.  
IMPORTANT  
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.  
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.  
NOTE ꢀ When installing refrigerant lines longer than 50  
feet, see the Lennox Refrigerant Piping Design and  
Fabrication Guidelines, CORP. 9351−L9, or contact  
Lennox Technical Support Product Applications for  
assistance. To obtain the correct information from Lennox,  
be sure to communicate the following information:  
Failure to properly flush the system per the  
instructions below will void the warranty.  
Table 2. Refrigerant Line Set ꢀ Inches (mm)  
Field Connections  
Recommended Line Set  
Model  
Liquid Line  
Suction Line  
Liquid Line  
Suction Line  
L15 Line Set  
XP16−024−230  
XP16−036−230  
XP16−048−230  
XP16−060−230  
3/8" (10 mm)  
3/8" (10 mm)  
3/8" (10 mm)  
3/4" (19 mm)  
3/8" (10 mm)  
3/4" (19 mm)  
L15−41 ꢀ 15 ft. − 50 ft. (4.6m − 15 m)  
7/8" (22 mm)  
3/8" (10 mm)  
3/8" (10 mm)  
7/8" (22 mm)  
L15−65 ꢀ 15 ft. − 50 ft. (4.6 m − 15 m)  
Field Fabricated  
1−1/8" (29 mm)  
1−1/8" (29 mm)  
NOTE ꢀ Some applications may required a field provided 7/8" to 1−1/8" adapter  
Page 9  
XP16 SERIES  
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Line Set Isolation ꢀ The following illustrations are examples of proper refrigerant line set isolation:  
REFRIGERANT LINE SET ꢀ INSTALLING  
VERTICAL RUNS (NEW CONSTRUCTION SHOWN)  
REFRIGERANT LINE SET ꢀ TRANSITION  
FROM VERTICAL TO HORIZONTAL  
NOTE ꢀ Insulate liquid line when it is routed through areas where the  
surrounding ambient temperature could become higher than the  
temperatureof the liquid line or when pressure drop is equal to or greater  
than 20 psig.  
ANCHORED HEAVY NYLON  
WIRE TIE OR AUTOMOTIVE  
AUTOMOTIVE  
MUFFLER-TYPE HANGER  
MUFFLER-TYPE HANGER  
OUTSIDE WALL  
LIQUID LINE  
VAPOR LINE  
WALL  
STUD  
WIRE TIE  
INSIDE WALL  
STRAP  
WOOD BLOCK  
BETWEEN STUDS  
STRAP LIQUID LINE TO  
VAPOR LINE  
NON−CORROSIVE  
METAL SLEEVE  
WIRE TIE  
LIQUID LINE  
NON−CORROSIVE  
METAL SLEEVE  
WOOD BLOCK  
WIRE TIE  
VAPOR LINE − WRAPPED  
IN ARMAFLEX  
STRAP  
REFRIGERANT LINE SET ꢀ INSTALLING  
HORIZONTAL RUNS  
SLEEVE  
To hang line set from joist or rafter, use either metal strapping material  
or anchored heavy nylon wire ties.  
WIRE TIE (AROUND  
VAPOR LINE ONLY)  
VAPOR LINE WRAPPED  
WITH ARMAFLEX  
8 FEET (2.43 METERS)  
OUTSIDE  
WALL  
STRAPPING  
MATERIAL (AROUND  
VAPOR LINE ONLY)  
FLOOR JOIST OR  
LIQUID  
LINE  
ROOF RAFTER  
TAPE OR  
WIRE TIE  
8 FEET (2.43 METERS)  
PVC  
PIPE  
CAULK  
NON−CORROSIVE  
METAL SLEEVE  
FIBERGLASS  
INSULATION  
STRAP THE VAPOR LINE TO THE JOIST  
OR RAFTER AT 8 FEET (2.43 METERS)  
INTERVALS THEN STRAP THE LIQUID  
LINE TO THE VAPOR LINE.  
TAPE OR  
WIRE TIE  
NOTE ꢀ Similar installation practices should be used if line set is  
to be installed on exterior of outside wall.  
FLOOR JOIST OR  
ROOF RAFTER  
Figure 7. Line Set Installation  
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Brazing Connections  
WARNING  
IMPORTANT  
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.  
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  
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  
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 ex-  
plosion, that could result in property  
damage, personal injury or death.  
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.  
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XP16 SERIES  
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CAP AND CORE REMOVAL  
CUT AND DEBUR  
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 / vapor and liquid line  
service ports.  
2
1
CUT AND DEBUR  
SERVICE PORT  
CAP  
SERVICE  
PORT  
CORE  
LINE SET SIZE MATCHES  
SERVICE VALVE CONNECTION  
SERVICE  
PORT  
CORE  
SERVICE VALVE  
CONNECTION  
SERVICE  
PORT CAP  
COPPER TUBE  
STUB  
LIQUID LINE SERVICE  
VALVE  
SUCTION / VAPOR LINE  
SERVICE VALVE  
REDUCER  
LINE SET SIZE IS SMALLER  
THAN CONNECTION  
DO NOT CRIMP SERVICE VALVE  
CONNECTOR WHEN PIPE IS  
SMALLER THAN CONNECTION  
REFRIGERANT LINE  
ATTACH THE MANIFOLD GAUGE SET FOR BRAZING LIQUID AND SUCTION / VAPOR LINE SERVICE  
VALVES  
3
Flow regulated nitrogen (at 1 to 2 psig) through the low−side refrigeration gauge set into the liquid line service port valve, and out of the suction /  
vapor line service port valve.  
A
B
C
Connect gauge set low pressure side to  
liquid line service valve (service port).  
USE REGULATOR TO FLOW  
NITROGEN AT 1 TO 2 PSIG.  
LOW  
HIGH  
Connect gauge set center port to bottle of  
nitrogenwith regulator.  
Remove core from valve in suction / vapor  
line service port to allow nitrogen to escape.  
ATTACH  
GAUGES  
B
SUCTION / VAPOR SERVICE PORT MUST BE  
OPEN TO ALLOW EXIT POINT FOR NITROGEN  
SUCTION /  
VAPOR LINE  
SERVICE  
VALVE  
C
VAPOR LINE  
OUTDOOR  
UNIT  
INDOOR  
UNIT  
NITROGEN  
LIQUID LINE SERVICE  
VALVE  
WHEN BRAZING LINE SET TO  
SERVICE VALVES, POINT FLAME  
AWAY FROM SERVICE VALVE.  
LIQUID LINE  
A
Figure 8. Brazing Procedures  
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).  
Page 12  
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WRAP SERVICE VALVES  
To help protect service valve seals during brazing, wrap water saturated cloths around service valve bodies and copper tube stubs. Use  
additionalwater 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 manifold gauge set connections  
5
6
BRAZE LINE SET  
Wrap both service valves with water saturated cloths as illustrated here and as mentioned in step 4, before brazing to line set. Water  
saturated cloths must remain water saturated throughout the brazing and cool−down process.  
LIQUID LINE SERVICE VALVE  
WHEN BRAZING LINE SET TO  
SERVICE VALVES, POINT FLAME  
AWAY FROM SERVICE VALVE.  
IMPORTANT ꢀ Allow braze joint to cool. Apply  
additional water saturated cloths to help cool brazed  
joint. Do not remove water saturated cloths until piping  
has cooled. Temperatures above 250ºF will damage  
valve seals.  
WATER SATURATED  
CLOTH  
LIQUID LINE  
WARNING  
SUCTION / VAPOR LINE  
SERVICE VALVE  
1. FIRE, PERSONAL INJURY, OR PROPERTY  
DAMAGE may 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.  
WHEN BRAZING LINE SET TO  
SERVICE VALVES, POINT FLAME  
AWAY FROM SERVICE VALVE.  
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.  
SUCTION / VAPOR LINE  
WATER SATURATED  
CLOTH  
PREPARATION FOR NEXT STEP  
After all connections have been brazed, disconnect manifold gauge set from service ports. Apply additional water saturated cloths to both  
service valves to cool piping. Once piping is cool, remove all water saturated cloths.  
7
Figure 9. Brazing Procedures (continued)  
Page 13  
XP16 SERIES  
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Indoor Refrigerant Metering Device Removal and Flushing Line Set and Indoor Coil  
Flushing is only required when the existing system used HCFC−22 refrigerant. If the existing system used HFC−410a, then  
remove the original indoor coil metering device and proceed to Installing New Indoor Metering Device on page 15.  
TYPICAL EXISTING FIXED ORIFICE  
REMOVAL PROCEDURE (UNCASED  
COIL SHOWN)  
TYPICAL EXISTING EXPANSION VALVE REMOVAL  
PROCEDURE (UNCASED COIL SHOWN)  
OR  
1B  
1A  
STUB END  
TWO PIECE PATCH PLATE  
(UNCASED COIL ONLY)  
LIQUID LINE  
ORIFICE  
HOUSING  
CHECK  
EXPANSION  
VALVE  
DISTRIBUTOR TUBES  
LIQUID LINE ORIFICE HOUSING  
DISTRIBUTOR  
TUBES  
®
TEFLON  
RING  
®
TEFLON RING  
FIXED ORIFICE  
BRASS NUT  
®
TEFLON  
RING  
SENSING  
LINE  
DISTRIBUTOR  
ASSEMBLY  
DISTRIBUTOR  
ASSEMBLY  
EQUALIZER  
LINE  
REMOVE AND DISCARD  
®
WHITE TEFLON SEAL  
(IF PRESENT)  
LIQUID LINE ASSEMBLY  
(INCLUDES STRAINER)  
LIQUID LINE  
ASSEMBLY WITH  
BRASS NUT  
A
B
On fully cased coils, remove the coil access and plumbing panels.  
Remove any shipping clamps holding the liquid line and distributor as-  
sembly.  
MALE EQUALIZER  
LINE FITTING  
VAPOR  
LINE  
C
Using two wrenches, disconnect liquid line from liquid line orifice hous-  
ing. Take care not to twist or damage distributor tubes during this pro-  
cess.  
LIQUID  
LINE  
SENSING BULB  
A
B
On fully cased coils, remove the coil access and plumbing panels.  
D
E
Remove and discard fixed orifice, valve stem assembly if present and  
®
Teflon washer as illustrated above.  
Remove any shipping clamps holding the liquid line and distributor  
assembly.  
Use a field−provided fitting to temporary reconnect the liquid line to the  
indoor unit’s liquid line orifice housing.  
C
Disconnect the equalizer line from the check expansion valve  
equalizer line fitting on the vapor line.  
D
E
Remove the vapor line sensing bulb.  
CONNECT GAUGES AND EQUIPMENT FOR  
FLUSHING PROCEDURE  
Disconnect the liquid line from the check expansion valve at the liquid  
line assembly.  
2
INVERTED HCFC−22  
GAUGE  
MANIFOLD  
F
Disconnect the check expansion valve from the liquid line orifice  
housing.Take care not to twist or damage distributor tubes during this  
process.  
CYLINDER CONTAINS  
CLEAN HCFC−22 TO BE  
USED FOR FLUSHING.  
A
®
G
H
Remove and discard check expansion valve and the two Teflon rings.  
LOW  
HIGH  
1
Use a field−provided fitting to temporary reconnect the liquid line to the  
indoor unit’s liquid line orifice housing.  
NEW  
OUTDOOR  
UNIT  
VAPOR LINE  
SERVICE VALVE  
FLUSHING LINE SET  
OPENED  
CLOSED  
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.  
EXISTING  
INDOOR  
UNIT  
3
B
LIQUID LINE SERVICE  
VALVE  
A
Set the recovery machine for liquid recovery and start the  
recovery machine. Open the gauge set valves to allow the  
RECOVERY  
CYLINDER  
TANK  
RETURN  
rBecovery machine to pull a vacuum on the existing system line  
set and indoor unit coil.  
C
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.  
INLET  
D
DISCHARGE  
RECOVERY MACHINE  
A
Inverted HCFC−22 cylinder with clean refrigerant to the vapor service  
valve.  
C
D
After all of the liquid refrigerant has been recovered, switch the  
recovery machine to vapor recovery so that all of the HCFC−22  
vapor is recovered. Allow the recovery machine to pull down to 0  
the system.  
B
C
HCFC−22 gauge set (low side) to the liquid line valve.  
HCFC−22 gauge set center port to inlet on the recovery machine with an  
empty recovery tank to the gauge set.  
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.  
D
Connect recovery tank to recovery machines per machine instructions.  
Figure 10. Removing Indoor Refrigerate Metering Device and Flushing Procedures  
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Installing New Indoor Metering Device  
This outdoor unit is designed for use in HFC−410A systems that use a check / expansion valve metering device (purchased  
separately) at the indoor coil.  
See the Lennox XP16 Engineering Handbook for approved check / expansion valve kit match−ups. The check / expansion  
valve device can be installed either 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  
1/2 Turn  
A
B
Remove the field−provided fitting that temporarily  
reconnectedthe liquid line to the indoor unit’s distributor  
assembly.  
INDOOR EXPANSION VALVE INSTALLATION  
TWO PIECE  
12  
PATCH PLATE  
(Uncased Coil Shown)  
1
11  
10  
®
(UNCASED  
STUB  
END  
2
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  
LIQUID LINE  
ORIFICE  
COIL ONLY)  
9
3
CHECK /  
EXPANSION  
VALVE  
4
8
HOUSING  
5
7
®
6
DISTRIBUTOR  
TUBES  
the Teflon ring with refrigerant oil.  
®
TEFLON  
RING  
C
D
E
Attach the stubbed end of the expansion valve to the  
liquid line orifice housing. Finger tighten and use an  
appropriatelysized wrench to turn an additional 1/2 turn  
clockwise as illustrated in the figure above, or 20 ft−lb.  
®
®
Place the remaining Teflon washer around the other  
end of the check / expansion valve. Lightly lubricate  
TEFLON  
RING  
SENSING  
LINE  
®
connector threads and expose surface of the Teflon  
ring with refrigerant oil.  
DISTRIBUTOR  
ASSEMBLY  
EQUALIZER  
LINE  
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  
illustratedin the figure above or 20 ft−lb.  
LIQUID LINE  
ASSEMBLY WITH  
BRASS NUT  
SENSING BULB INSTALLATION  
A
Attach the vapor line sensing bulb in the proper  
orientationas illustrated to the right using the clamp and  
screws provided.  
1/8 Turn  
MALE EQUALIZER LINE  
FITTING (SEE  
VAPOR  
LINE  
EQUALIZER LINE  
INSTALLATION FOR  
FURTHER DETAILS)  
NOTE ꢀ Confirm proper thermal contact between vapor line  
and expansion bulb before insulating the sensing bulb once  
installed.  
12  
1
5
11  
10  
2
LIQUID LINE  
9
3
4
8
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.  
7
Sensing bulb insulation is  
required if mounted external to  
the coil casing.  
6
ON LINES SMALLER THAN  
7/8", MOUNT SENSING  
BULB AT EITHER THE 3 OR  
9 O’CLOCK POSITION.  
VAPOR LINE  
EQUALIZER LINE INSTALLATION  
Remove and discard either the flare seal cap or flare nut with  
copper flare seal bonnet from the equalizer line port on the vapor  
line as illustrated in the figure to the right.  
12  
BULB  
BULB  
FLARE SEAL CAP  
FLARE NUT  
VAPOR LINE  
ON 7/8" AND LARGER LINES,  
MOUNT SENSING BULB AT  
EITHER THE 4 OR 8 O’CLOCK  
POSITION. NEVER MOUNT ON  
BOTTOM OF LINE.  
COPPER FLARE  
SEAL BONNET  
OR  
12  
MALE BRASS EQUALIZER  
LINE FITTING  
BULB  
BULB  
NOTE ꢀ NEVER MOUNT ON BOTTOM OF LINE.  
VAPOR LINE  
Figure 11. Installing Indoor Check / Expansion Valve  
Page 15  
XP16 SERIES  
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Leak Test Line Set and Indoor Coil  
IMPORTANT  
Leak detector must be capable of sensing HFC refrigerant.  
CONNECT GAUGE SET  
A
Connect an HFC−410A manifold gauge set high pressure hose to the  
vapor valve service port.  
LOW  
HIGH  
MANIFOLD GAUGE SET  
NOTE ꢀ Normally, the high pressure hose is connected to the liquid  
line port. However, connecting it to the vapor port better protects the  
manifoldgauge set from high pressure damage.  
B
With both manifold valves closed, connect the cylinder of HFC−410A  
refrigerantto the center port of the manifold gauge set.  
OUTDOOR UNIT  
NOTE ꢀ Later in the procedure, the  
HFC−410A container will be replaced by  
the nitrogen container.  
A
B
TO VAPOR  
SERVICE VALVE  
NITROGEN  
HFC−410A  
Figure 12. Manifold Gauge Set Connections for Leak Testing  
TEST FOR LEAKS  
side of the manifold gauge set. Disconnect the  
HFC−410A cylinder.  
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:  
3. Connect a cylinder of dry nitrogen with a pressure  
regulating valve to the center port of the manifold  
gauge set.  
1. 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).  
4. 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.  
2. 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  
5. 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.  
6. After leak testing disconnect gauges from service  
ports.  
Page 16  
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Evacuating Line Set and Indoor Coil  
Evacuating the system of non−condensables is critical for proper operation of the unit. Non−condensables are defined as any  
gas that will not condense under temperatures and pressures present during operation of an air conditioning system.  
Non−condensables and water suction combine with refrigerant to produce substances that corrode copper piping and  
compressor parts.  
CONNECT GAUGE SET  
NOTE ꢀ Remove cores from service valves (if not already done).  
LOW  
HIGH  
1
A
Connect low side of manifold gauge set  
with 1/4 SAE in−line tee to vapor line  
service valve  
B
C
D
Connect high side of manifold gauge  
set to liquid line service valve  
OUTDOOR  
UNIT  
MANIFOLD  
GAUGE SET  
A34000 1/4 SAE TEE WITH  
SWIVEL COUPLER  
Connect micron gauge available  
connector on the 1/4 SAE in−line tee.  
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.  
A
500  
MICRON  
GAUGE  
C
TO VAPOR  
SERVICE VALVE  
NITROGEN  
HFC−410A  
B
VACUUM PUMP  
TO LIQUID LINE  
SERVICE VALVE  
D
EVACUATE THE SYSTEM  
RECOMMEND  
MINIMUM 3/8" HOSE  
A
B
Open both manifold valves and start the vacuum pump.  
Evacuate the line set and indoor unit to an absolute pressure of 23,000 microns (29.01 inches of mercury).  
2
NOTE ꢀ During the early stages of evacuation, it is desirable to close the manifold gauge valve at least once. A rapid rise in pressure  
indicates a relatively large leak. If this occurs, repeat the leak testing procedure.  
NOTE ꢀ The term absolute pressure means the total actual pressure within a given volume or system, above the absolute zero of  
pressure. Absolute pressure in a vacuum is equal to atmospheric pressure minus vacuum pressure.  
C
When the absolute pressure reaches 23,000 microns (29.01 inches of mercury), perform the following:  
S
S
S
S
S
S
Close manifold gauge valves  
Close valve on vacuum pump and turn off vacuum pump  
Disconnect manifold gauge center port hose from vacuum pump  
Attach manifold center port hose to a dry nitrogen cylinder with pressure regulator set to 150 psig (1034 kPa) and purge the hose.  
Open manifold gauge valves to break the vacuum in the line set and indoor unit.  
Close manifold gauge valves.  
D
E
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.  
Reconnect the manifold gauge to the vacuum pump, turn the pump on, and continue to evacuate the line set and indoor unit until the  
absolutepressure 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.  
1/6 TURN  
G
Perform the following:  
S
S
S
S
Close manifold gauge valves.  
Shut off HFC−410A cylinder.  
12  
1
5
11  
7
2
4
10  
Reinstall service valve cores by removing manifold hose from service valve. Quickly install cores with core  
tool while maintaining a positive system pressure.  
9
3
8
Replace stem caps and secure finger tight, then tighten an additional one−sixth (1/6) of a turn as illustrated.  
6
Figure 13. Evacuating Line Set and Indoor Coil  
Page 17  
XP16 SERIES  
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Electrical Connections  
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.  
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.  
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.  
24VAC TRANSFORMER  
Use the transformer provided with the furnace or air  
handler for low-voltage control power (24VAC − 40 VA  
minimum)  
INSTALL THERMOSTAT  
SIZE CIRCUIT AND INSTALL DISCONNECT  
SWITCH  
Install room thermostat (ordered separately) on an inside wall  
2approximately 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.  
1
Refer to the unit nameplate for minimum circuit ampacity, and  
maximum fuse or circuit breaker (HACR per NEC). Install power  
wiring and properly sized disconnect switch.  
THERMOSTAT  
MAIN FUSE BOX/  
BREAKER PANEL  
DISCONNECT  
SWITCH  
5 FEET  
(1.5M)  
NOTE ꢀ 24VAC, Class II circuit connections are made in the control  
panel.  
NOTE ꢀ Units are approved for use only with copper conductors.  
Ground unit at disconnect switch or to an earth ground.  
WARNING  
Electric Shock Hazard. Can cause injury or death. Unit must be grounded in accordance with national and  
local codes.  
Line voltage is present at all components when unit is not in operation on units with single-pole contactors.  
Disconnect all remote electric power supplies before opening access panel. Unit may have multiple power  
supplies.  
Page 18  
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HIGH VOLTAGE FIELD WIRING  
LOW VOLTAGE CONNECTIONS  
LOW VOLTAGE (24V) FIELD WIRING  
3
WIRE RUN LENGTH  
AWG# INSULATION TYPE  
LESS THAN 100’ (30 METERS)  
MORE THAN 100’ (30 METERS)  
18  
16  
TEMPERATURE RATING  
35ºC MINIMUM.  
NOTE − For proper voltages, select thermostat wire (control wires)  
gauge per table above.  
NOTE − Do not bundle any excess 24VAC control wires inside  
control box.  
C
A
B
C
D
Run 24VAC control wires through cutout with grommet.  
Run 24VAC control wires through wire tie.  
Make 24VAC control wire connections.  
Tighten wire tie to security 24V control wiring.  
NOTE − Wire tie provides low voltage wire strain relief and to maintain  
separation of field installed low and high voltage circuits.  
CUTOUT WITH  
A
GROMMET  
TIGHTEN WIRE TIE  
24V CONTROL WIRES  
D
B
connections when connecting unit to either a CBX32MV or CBX40UHV in non−communicating mode. For connections to other Lennox air handlers  
or furnaces, see the ComfortSense® 7000 installation instruction for further match component wiring illustrations.  
HIGH VOLTAGE POWER SUPPLY CONNECTIONS  
OUTDOOR UNIT  
CONTROL BOX  
4
GROUND  
G
NOTE − Any excess high voltage field wiring  
should be trimmed and secured away from  
any low voltage field wiring.  
L1  
L2  
NOTE − To facilitate a conduit, a cutout is lo-  
cated in the bottom of the control box. Connect  
conduit to the control box using a proper con-  
duit fitting.  
CONDUIT  
CUTOUT  
CONDUIT  
Page 19  
XP16 SERIES  
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CBX32MV  
OR  
CBX40UHV  
COMFORTSENSET  
HEAT PUMP UNIT  
(TWO−STAGE)  
7000  
X2658 OUTDOOR SENSOR IS REQUIRED FOR OUTDOOR  
TEMPERATURE DISPLAY, DEW POINT CONTROL, HEAT PUMP AND  
DUAL FUEL BALANCE POINTS.  
1
R
R
R
CONNECTED ON UNIT WITH LSOM. RESISTOR KIT (CAT # 47W97)  
IS REQUIRED WHEN CONNECTING THE COMFORTSENSE 7000  
WITH THE LSOM 2.  
2
W3  
H
W2  
W2  
W1  
O
3
FIELD PROVIDED JUMPER BETWEEN Y2 OUT BL ON HEAT PUMP  
TO Y2 ON CBX40UHV.  
1
W1  
W1  
O. D.  
SENSOR  
(X2658)  
AIR  
HANDLER  
CONTROL  
O
O
L
2
L
IMPORTANT − USE CARE WHEN CUTTING LINKS TO  
PREVENT DAMAGE TO CONTROL. SEE CBX40UHV  
INSTALLATION INSTRUCTION FOR FURTHER DETAILS.  
Y1  
Y1  
Y2  
Y1  
Y2  
G
Y1−Y2  
2−STAGE  
COMPR  
CUT ON−BOARD LINK Y1−Y2 FOR TWO−STAGE HP  
CUT ON−BOARD LINK R −O.  
G
Y2  
OUT  
BL  
D
DS  
Y2  
3
R−O  
HEAT  
PUMP  
T
T
B
C
R−DS  
DEHUM  
OR  
C
C
CUT ON−BOARD LINK R−DS WHEN DEHUMIDIFICATION TERMINAL IS USED.  
HARMONY  
Figure 14. Typical Field Wiring ꢀ Heat Pump Application with CBX32MV or CBX40UHV  
CBX32MV OR  
CBX40UHV  
COMFORTSENSEt  
OUTDOOR UNIT  
7000 THERMOSTAT  
RED  
RED  
OUTDOOR  
SENSOR  
FAN RELAY (NOT REQUIRED  
WITH SINGLESPEED  
OUTDOOR FAN)  
BLACK  
PURPLE  
T
T
PURPLE  
(X2658)  
BLACK  
YELLOW  
BLUE  
BROWN (NOT USED FOR APPLICATIONS WITHOUT LSOM  
BLUE (NOT REQUIRED FOR SINGLE STAGE)  
AIR  
HANDLER  
CONTROL  
IMPORTANT − USE CARE WHEN CUTTING LINKS TO  
PREVENT DAMAGE TO CONTROL. SEE CBX40UHV  
INSTALLATION INSTRUCTION FOR FURTHER DETAILS.  
Y1−Y2  
2−STAGE  
COMPR  
RESISTOR KIT (CAT # 47W97) IS REQUIRED  
WHEN CONNECTING THE COMFORTSENSE  
7000 WITH THE LSOM 2.  
CUT ON−BOARD LINK Y1−Y2 FOR TWO−STAGE A/C ONLY  
CUT ON−BOARD LINK R −O.  
R−O  
HEAT  
PUMP  
R−DS  
DEHUM  
OR  
CUT ON−BOARD LINK R−DS WHEN DEHUMIDIFICATION  
TERMINAL IS USED.  
HARMONY  
®
Figure 15. Heat Pump Application ꢀ Humiditrol and Second−Stage Outdoor Fan Relay Wiring with  
CBX32MV or CBX40UHV  
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Figure 16. Typical Unit Wiring Diagram (−024, −036 and −048 Only)  
Page 21  
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Figure 17. Typical Unit Wiring Diagram (−060 Only)  
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Figure 18. Typical Factory Wiring Diagram (No Field Modifications)  
have consulted with the power company and the  
voltage condition has been corrected.  
Unit Start−Up  
6. Open both the liquid and vapor line service valves to  
release the refrigerant charge contained in outdoor  
unit into the system.  
IMPORTANT  
If unit is equipped with a crankcase heater, it should be  
energized 24 hours before unit start−up to prevent  
compressor damage as a result of slugging.  
7. Use figure 19 to determine next step in system  
preparation.  
OPEN BOTH VAPOR AND LIQUID SERVICE  
VALVE STEMS TO RELEASE  
REFRIGERANT FROM OUTDOOR UNIT TO  
SYSTEM.  
UNIT START−UP  
1. Rotate fan to check for binding.  
2. Inspect all factory− and field−installed wiring for loose  
connections.  
3. Verify that the manifold gauge set is connected as  
illustrated in figure 21. Use a temperature sensor  
positioned near the liquid line service port as illustrated  
in figure 21 which will be required later when using the  
subcooling method for optimizing the system  
refrigerant charge.  
NO  
YES  
GO TO SERVICE AND WEIGH  
IN REFRIGERANT CHARGE  
FOR OUTDOOR UNITS  
DELIVERED VOID OF CHARGE  
ON PAGE 24.  
GO TO OPTIMIZING SYSTEM  
REFRIGERANT CHARGE ON  
PAGE 26.  
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  
Figure 19. Outdoor Unit Factory Charge  
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Service and Weigh In Refrigerant for Outdoor Units Delivered Void of Charge  
The following procedures are only required if it has been determine that the new outdoor unit is void of charge. Skip to the  
next section if refrigerant charge is present.  
LEAK CHECK, REPAIR AND EVACUATE  
2. Connect the manifold gauge set’s low pressure side to  
the true suction port.  
If the outdoor unit is void of refrigerant, clean the system  
using the procedure described below.  
3. Connect the manifold gauge set’s high pressure side  
to the liquid line service port.  
1. Leak check system using procedures provided on  
page 16. Repair any leaks discovered during leak test.  
4. Connect the center hose of the gauge set to acylinder  
of HFC−410A and purge the hose. Then, place the  
cylinder upside down on a scale.  
2. Evacuate the system using procedure provided in  
5. Check that fan rotates freely.  
3. Use nitrogen to break the vacuum and install a new  
filter drier in the system.  
6. Inspect all factory− and field−installed wiring for loose  
connections.  
4. Evacuate the system again using procedure in figure  
12.  
7. Open the high side manifold gauge valve and weigh in  
liquid refrigerant. Use figure 20 in calculating the  
correct weigh−in charge.  
CONNECT MANIFOLD GAUGE SET AND WEIGH IN  
CHARGE  
8. Close manifold gauge valves.  
9. Monitor the system to determine the amount of  
moisture remaining in the oil. It may be necessary to  
replace the bi−flow filter drier several times to achieve  
the required dryness level. If system dryness is not  
verified, the compressor will fail in the future.  
After the evacuation procedure, reconnect the manifold  
required for initial system weigh in charging.  
1. Close manifold gauge set valves and connect the  
center hose to a cylinder of HFC−410A. Set for liquid  
phase charging.  
10. Continue to Optimizing System Refrigerant Charge  
on page 26 to optimize the system charge using  
subcooling method.  
WEIGH−IN CHARGING  
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  
refrigerantcharge:  
Additional charge specified per indoor  
Adjust amount. for variation in line set  
length listed on line set length table below.  
Amount specified on  
nameplate  
Total Charge  
+
=
+
Refrigerant Charge per Line Set Length  
OUNCES PER 5 FEET (G PER 1.5 M) ADJUST FROM 15 FEET  
(4.6 M) LINE SET*  
LIQUID LINE SET DIAMETER  
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.  
NOTE ꢀ Insulate liquid line when it is routed through areas where the surrounding ambient temperature could become higher than the temperature  
of the liquid line or when pressure drop is equal to or greater than 20 psig.  
NOTE ꢀ The above nameplate is for illustration purposes only. Go to actual nameplate on outdoor unit for charge information.  
Figure 20. Using HFC−410A Weigh In Method  
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MANIFOLD GAUGE SET  
HIGH  
LOW  
GAUGE SET  
B
CONNECTIONS FOR OPTIMIZING SYSTEM CHARGE  
TRUE SUCTION PORT  
CONNECTION  
OUTDOOR UNIT  
NOTE ꢀ Refrigerant tank should be  
turned right−side−up to deliver vapor  
during charge optimizing procedure.  
REFRIGERANT  
TANK  
A
CHARGE IN  
LIQUID PHASE  
DIGITAL SCALE  
TO LIQUID  
LINE SERVICE  
VALVE  
TEMPERATURE SENSOR  
(LIQUID LINE)  
C
D
TEMPERATURE SENSOR (USE FOR  
SUBCOOLING METHOD)  
A
B
C
D
Close manifold gauge set valves and connect the center hose to a cylinder of HFC−410A. Set for liquid phase charging.  
Connect the manifold gauge set’s low pressure side to the true suction port.  
INSIDE OUTDOOR UNIT  
Connect the manifold gauge set’s high pressure side to the liquid line service port.  
Position temperature sensor on liquid line near liquid line service port (use only for subcooling method).  
Figure 21. Gauge Set Connections for Adding Refrigerant  
DISTRIBUTOR  
OUTDOOR UNIT  
NOTE − ARROWS INDICATE DIRECTION  
OF REFRIGERANT FLOW  
REVERSING VALVE  
CHECK / EXPANSION  
VALVE  
OUTDOOR  
COIL  
INDOOR UNIT  
BI−FLOW FILTER / DRIER  
MUFFLER  
TRUE SUCTION  
PORT  
VAPOR  
SERVICE  
PORT  
LIQUID LINE  
SERVICE PORT  
COMPRESSOR  
CHECK / EXPANSION VALVE  
INDOOR  
COIL  
NOTE − Use gauge ports on vapor line valve and liquid valve for evacuating refrigerant lines and  
indoor coil. Use true suction port to measure vapor pressure during charging.  
Figure 22. Heat Pump Cooling Cycle  
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Optimizing System Refrigerant Charge  
This section provides instructions on optimizing the  
system charge. This section includes:  
efficiency. Make any air flow adjustments before  
continuing with the optimizing procedure.  
S
S
S
S
Optimizing procedure  
Adjusting indoor airflow  
Using subcooling method  
5. Use subcooling method to optimize the system  
charge (see figure 24). Adjust charge as necessary.  
ADJUSTING INDOOR AIRFLOW  
Approved matched components, targeted subcooling  
(SC) values and add charge values  
Heating Mode Indoor Airflow Check  
(Only use when indoor unit has electric heat)  
S
Normal operating pressures  
Temperature pressures  
S
Indoor blower airflow (CFM) may be calculated by  
energizing electric heat and measuring:  
OPTIMIZING PROCEDURE  
S
S
Temperature rise between the return air and supply air  
temperatures at the indoor coil blower unit,  
1. Move the low−side manifold gauge hose from the  
vapor line service valve to the true suction port (see  
Measuring voltage supplied to the unit,  
S
Measuring amperage being drawn by the heat unit(s).  
2. Set the thermostat for either cooling or heating  
demand. Turn on power to the indoor unit and close  
the outdoor unit disconnect switch to start the unit.  
Then, apply the measurements taken in the following  
formula to determine CFM:  
Amps x Volts x 3.41  
CFM =  
1.08 x Temperature rise (F)  
3. Allow unit to run for five minutes to allow pressures to  
stabilize.  
Cooling Mode Indoor Airflow Check  
Check airflow using the Delta−T (DT) process using figure  
23.  
4. Check the airflow as instructed under Adjusting Indoor  
Airflow to verify or adjust indoor airflow for maximum  
ADJUSTING INDOOR AIRFLOW  
DT  
Temp.  
of air  
entering  
indoor  
coil ºF  
1. Determine the desired DTꢀMeasure entering air temper-  
ature using dry bulb (A) and wet bulb (B). DT is the intersect-  
ing value of A and B in the table (see triangle).  
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  
2. Find temperature drop across coilꢀMeasure the coil’s dry  
bulb entering and leaving air temperatures (A and C). Tem-  
A
perature Drop Formula: (T  
) = A minus C.  
Drop  
Wet−bulb ºF  
57 58 59 60 61 62 63 64 65 66 67 68 69 70  
B
3. Determine if fan needs adjustmentꢀIf the difference between  
the measured T and the desired DT (T DT) is within  
Drop  
Drop  
+3º, no adjustment is needed. See examples: Assume DT =  
15 and A temp. = 72º, these C temperatures would necessi-  
tate stated actions:  
A
T
Drop  
C
72º  
19º  
53º  
Cº  
T
DT  
=
ºF ACTION  
Drop  
19  
B
air flow  
air flow  
53º  
58º  
62º  
15  
15  
15  
=
=
=
4
Increase the airflow  
DRY  
BULB  
DRY  
BULB  
64º  
14  
−1 (within +3º range) no change  
10  
−5 Decrease the airflow  
WET  
BULB  
INDOOR  
COIL  
All temperatures are  
expressed in ºF  
4. Adjust the fan speedꢀSee indoor unit instructions to in-  
crease/decrease fan speed.  
Changing air flow affects all temperatures; recheck tempera-  
tures to confirm that the temperature drop and DT are within  
+3º.  
Figure 23. Checking Airflow over Indoor Coil Using Delta−T Formula  
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OPTIMIZE CHARGE USING SUBCOOLING METHOD  
1. Check liquid and vapor line pressures. Compare pressures with either second−stage  
heat or cooling mode normal operating pressures listed in table 7. Table 7 is a general  
guide and expect minor pressures variations. Significant pressure differences may  
indicate improper charge or other system problem.  
2. Decide whether to use cooling or heating mode based on current outdoor ambient  
temperature:  
USE  
COOLING  
MODE  
A
Use COOLING MODE when:  
60ºF  
(15ºC)  
S
S
Outdoor ambient temperature is 60°F (15.5°C) and above.  
USE  
HEATING  
MODE  
Indoor return air temperature range is between 70 to 80°F (21−27°C). This  
temperature range is what the target subcooling values are base upon in  
tables 3 through 6.  
If indoor return air temperature is not within reference range, set thermostat to  
cooling mode and a setpoint of 68ºF (20ºC). This should place the outdoor unit  
into second−stage (high−capacity) cooling mode. When operating and  
temperature pressures have stabilized, continue to step 3.  
B
Use HEATING MODE when:  
S
S
Outdoor ambient temperature is 59°F (15.0°C) and below.  
Indoor return air temperature range is between 65−75°F (18−24°C). This  
temperature range is what the target subcooling values are base upon in  
tables 3 through 6.  
If indoor return air temperature is not within reference range, set thermostat to  
heating mode and a setpoint of 77ºF (25ºC). This should place the outdoor unit  
into second−stage (high−capacity) heating mode. When operating and  
temperature pressures have stabilized, continue to step 3.  
3. Read the liquid line pressure; then find its corresponding temperature pressure listed  
in table 8 and record it in the SATº space to the left.  
4. Read the liquid line temperature; record in the LIQº space to the left.  
SATº  
LIQº  
SCº  
5. Subtract LIQº temperature from SATº temperature to determine subcooling; record  
it in SCº space to the left..  
6. Compare SCº results with tables 3 through 6 (either Heating or Cooling mode  
column), also consider any additional charge required for line set lengths longer than  
15 feet and/or unit matched component combinations (Add Charge column).  
=
7. If subcooling value is:  
A
B
GREATER than shown for the applicable unit match component, REMOVE  
refrigerant;  
LESS than shown for the applicable unit match component, ADD refrigerant.  
8. If refrigerant is added or removed, repeat steps 3 through 6 to verify charge.  
9. Close all manifold gauge set valves and disconnect gauge set from outdoor unit.  
10. Replace the stem and service port caps and tighten as specified in Operating Service  
Valves on page 2.  
11. Recheck voltage while the unit is running. Power must be within range shown on the  
nameplate.  
Figure 24. Using HFC−410A Subcooling Method ꢀ Second Stage (High Capacity)  
Page 27  
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APPROVED MATCHED SYSTEM COMPONENTS, TARGETED SUBCOOLING (SC) VALUES AND  
ADD CHARGE VALUES  
Listed below are the approved matched system components (air handlers and indoor coils), targeted subcooling and  
add charge values for the XP16. This information is also listed on the unit charging sticker located on the outdoor unit  
access panel.  
Subcooling values listed in the following tables are based  
on outdoor ambient air temperature of:  
Table 5. XP16048230  
Heating  
Mode  
+5ºF  
Cooling  
Mode  
+1ºF  
*Add Charge  
Indoor Air Handers  
and Coils  
S
S
60°F (15.5°C) and above for cooling mode  
59°F (15.0°C) and below for heating mode.  
Subcooling  
lbs.  
1
1
3
1
1
1
1
1
1
1
1
2
2
0
1
0
0
1
1
1
oz.  
4
Table 3. XP16024230  
CBX26UH−048−230  
CBX27UH−048−230  
CBX27UH−060−230  
CBX32M−048  
CBX32M−060  
CBX32MV−048  
CBX32MV−060  
CBX32MV−068  
CBX40UHV−048  
CBX40UHV−060  
CH23−68  
10  
19  
13  
19  
14  
19  
14  
9
8
9
Heating  
Mode  
+5ºF  
Cooling  
Mode  
+1ºF  
4
*Add Charge  
Indoor Air Handers  
and Coils  
14  
9
3
Subcooling  
lb.  
0
0
1
0
1
1
1
1
1
0
1
1
oz.  
15  
9
4
CBX26UH−024  
CBX27UH−024−230  
CBX27UH−030−230  
CBX32MV−024/030  
CBX32MV−036  
CBX40UHV−024  
CBX40UHV−030  
CBX40UHV−036  
CH33−31B  
45  
20  
17  
20  
17  
17  
17  
17  
31  
45  
24  
18  
6
7
7
7
7
7
7
7
8
4
7
8
9
11  
4
9
3
9
11  
11  
4
9
8
3
19  
14  
24  
19  
19  
13  
11  
15  
15  
14  
9
9
3
9
11  
12  
5
3
10  
9
3
CH33−49C  
12  
0
CH33−50/60C  
CH33−60D  
9
5
CR33−30/36A/B/C  
CX34−31A/B  
8
0
11  
10  
CH33−62D  
9
4
CX34−38A/B  
CR33−50/60C  
CR33−60D  
7
10  
10  
0
Table 4. XP16036230  
7
Heating  
Mode  
+5ºF  
Cooling  
Mode  
+1ºF  
CX34−60D  
8
*Add Charge  
Indoor Air Handers  
and Coils  
CX34−62D  
9
6
Subcooling  
lbs.  
0
oz.  
0
CX34−62C  
8
9
9
CBX26UH−036  
CBX27UH−036−230  
CBX27UH−042−230  
CBX32M−036  
CBX32MV−036  
CBX32MV−048  
CBX40UHV−030  
CBX40UHV−036  
CBX40UHV−042  
CBX40UHV−048  
CH33−43B  
50  
22  
24  
22  
22  
24  
22  
22  
24  
24  
13  
37  
37  
49  
29  
29  
5
7
Table 6. XP16060230  
0
9
Heating  
Mode  
+5ºF  
Cooling  
Mode  
+1ºF  
*Add Charge  
Indoor Air Handers  
and Coils  
11  
7
3
0
0
9
Subcooling  
lbs.  
4
oz.  
13  
3
7
0
9
CBX26UH−060  
CBX27UH−060−230  
CBX32M−060  
CBX32MV−060  
CBX32MV−068  
CBX40UHV−060  
CH23−682  
20  
10  
17  
17  
15  
17  
37  
33  
15  
24  
24  
21  
13  
9
6
6
6
7
6
9
8
7
7
7
9
7
11  
7
3
0
2
0
9
1
12  
12  
1
7
0
9
1
11  
11  
10  
11  
11  
7
3
0
2
3
0
1
12  
10  
0
2
7
2
CH33−48C  
2
11  
11  
9
CH33−50/60C  
CH33−62D  
1
CH33−43C  
2
1
4
CR33−48B/C  
0
CR33−50/60C  
CR33−60D  
0
0
CX34−43B/C  
9
2
11  
11  
0
0
CX34−50/60C  
9
2
CX34−62C  
2
16  
4
CX34−62D  
1
*Amount of charge required in additional to charge shown on unit  
nameplate. (Remember to consider line set length difference.)  
Page 28  
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NORMAL OPERATING PRESSURES  
TEMPERATURE PRESSURES  
Use the following tables to perform maintenance checks; it  
is not a procedure for charging the system. Minor  
variations in these pressures may be due to differences in  
installations. Significant deviations could mean that the  
system is not properly charged or that a problem exists  
with some component in the system.  
Compute subcooling by determining saturated  
condensing temperature from temperature pressure  
chart. Subtract from liquid temperature entering TXV.  
Table 8. HFC−410A Temperature (°F) −  
Pressure (Psig)  
°F  
Psig  
°F Psig  
°F Psig  
°F Psig  
Typical pressures only, expressed in psig (liquid +/− 10  
and vapor +/− 5 psig); matched indoor component (air  
handler or coil), indoor air quality, and indoor load will  
cause the pressures to vary.  
32  
33  
34  
35  
100.8  
102.9  
105.0  
107.1  
63  
64  
65  
66  
178.5  
181.6  
184.3  
187.7  
94  
95  
96  
97  
290.8  
295.1  
299.4  
303.8  
125  
126  
127  
128  
445.9  
451.8  
457.6  
463.5  
Table 7. Normal Operating Pressures*  
Normal Operating Pressures − Cooling  
XP16  
−024  
Vap  
First Stage (Low Capacity) Pressure  
−036  
−048  
−060  
Liq  
36  
37  
38  
39  
40  
41  
42  
43  
44  
45  
46  
47  
48  
49  
50  
51  
52  
53  
54  
55  
56  
57  
58  
59  
60  
61  
62  
109.2  
111.4  
113.6  
115.8  
118.0  
120.3  
122.6  
125.0  
127.3  
129.7  
132.2  
134.6  
137.1  
139.6  
142.2  
144.8  
147.4  
150.1  
152.8  
155.5  
158.2  
161.0  
163.9  
166.7  
169.6  
172.6  
175.4  
67  
68  
69  
70  
71  
72  
73  
74  
75  
76  
77  
78  
79  
80  
81  
82  
83  
84  
85  
86  
87  
88  
89  
90  
91  
92  
93  
190.9  
194.1  
197.3  
200.6  
203.9  
207.2  
210.6  
214.0  
217.4  
220.9  
224.4  
228.0  
231.6  
235.3  
239.0  
242.7  
246.5  
250.3  
254.1  
258.0  
262.0  
266.0  
270.0  
274.1  
278.2  
282.3  
286.5  
98  
308.2  
312.7  
317.2  
321.8  
326.4  
331.0  
335.7  
340.5  
345.3  
350.1  
355.0  
360.0  
365.0  
370.0  
375.1  
380.2  
385.4  
390.7  
396.0  
401.3  
406.7  
412.2  
417.7  
423.2  
428.8  
434.5  
440.2  
129  
130  
131  
132  
133  
134  
135  
136  
137  
138  
139  
140  
141  
142  
143  
144  
145  
146  
147  
148  
149  
150  
151  
152  
153  
154  
155  
469.5  
475.6  
481.6  
487.8  
494.0  
500.2  
506.5  
512.9  
519.3  
525.8  
532.4  
539.0  
545.6  
552.3  
559.1  
565.9  
572.8  
579.8  
586.8  
593.8  
601.0  
608.1  
615.4  
622.7  
630.1  
637.5  
645.0  
F  
(C)**  
Liq  
Liq  
Vap  
Liq Vap  
Vap  
99  
100  
101  
102  
103  
104  
105  
106  
107  
108  
109  
110  
111  
112  
113  
114  
115  
116  
117  
118  
119  
120  
121  
122  
123  
124  
65  
(18.3)  
226  
260  
301  
346  
396  
451  
144  
145  
148  
151  
153  
156  
220  
254  
295  
340  
389  
444  
141  
144  
148  
150  
153  
156  
224  
259  
302  
346  
396  
450  
143  
143  
147  
149  
152  
155  
230  
267  
311  
357  
398  
453  
137  
139  
141  
144  
147  
149  
75  
(23.9)  
85  
(29.4)  
95  
(35.0)  
105  
(40.6)  
115  
(46.1)  
Second Stage (High Capacity) Pressure  
65  
(18.3)  
241  
279  
321  
369  
421  
480  
140  
142  
144  
146  
148  
151  
232  
269  
312  
346  
409  
465  
129  
136  
140  
142  
145  
148  
238  
278  
321  
372  
424  
481  
138  
140  
142  
144  
147  
149  
232  
276  
320  
367  
421  
479  
131  
133  
136  
138  
141  
144  
75  
(23.9)  
85  
(29.4)  
95  
(35.0)  
105  
(40.6)  
115  
(46.1)  
Normal Operating Pressures − Heating  
First Stage (Low Capacity) Pressure  
50  
(10)  
312  
330  
112  
130  
350  
372  
115  
136  
336  
363  
114  
135  
385  
414  
108  
126  
60  
(15.5)  
Second Stage (High Capacity) Pressure  
20  
(−7.0)  
299  
312  
325  
344  
358  
64  
79  
321  
347  
367  
387  
395  
61  
74  
289  
294  
321  
341  
361  
57  
69  
332  
349  
361  
383  
425  
59  
67  
30  
(−1.0)  
40  
(4.4)  
93  
90  
80  
75  
50  
(10)  
110  
128  
110  
131  
110  
128  
85  
60  
(15.5)  
122  
** Temperature of air entering outdoor coil.  
Page 29  
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UNIT COMPONENTS  
Demand Defrost Control (A108)  
System Operation  
The demand defrost control measures differential  
temperatures to detect when the system is performing  
poorly because of ice build−up on the outdoor coil. The  
controller self−calibrates when the defrost system starts  
and after each system defrost cycle. The demand defrost  
control’s: components are shown in figure 25.  
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.  
S
S
S
Demand defrost control connections, jumpers and  
This section addresses:  
Demand defrost control connections, jumpers and  
LED descriptions are listed on table 9.  
S
S
Unit components (sensors, temperature switch,  
pressure switches and demand defrost control)  
Demand defrost control status, fault and lockout LEDs  
are listed in table 10.  
Second−stage operation  
TEST PINS (P1)  
LOW AMBIENT  
THERMOSTAT PINS  
(P3)  
DEFROST TERMINATION  
PIN SETTINGS (P1)  
SENSOR PLUG IN  
(COIL AND  
AMBIENT  
SENSORS) (P4)  
DIAGNOSTIC LEDS  
(DS1 AND DS2)  
DELAY PINS  
(P5)  
24V TERMINAL STRIP  
CONNECTIONS (P2)  
REVERSING VALVE  
(O OUT)  
PRESSURE SWITCH  
CIRCUIT  
CONNECTIONS  
Note − Component locations vary by board manufacturer.  
Figure 25. Demand Defrost Control (A108)  
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Table 9. Demand Defrost Control (A108) Inputs, Outputs and Configurable Settings  
Control Control Label or  
Locations Description  
Purpose  
Function  
P1  
P1  
TEST  
Test Mode  
See Test Mode on page 39 for further details.  
The demand defrost control as illustrated in figure 25 has valid selections  
which are: 50, 70, 90, and 100°F (10, 21, 32 and 38°C). The shunt  
terminationpin is factory set at 50°F (10°C). If the temperature shunt is  
not installed, the default termination temperature is 90°F (32°C).  
Defrost Temperature  
Termination Shunt (Jumper)  
Pins  
50, 70, 90, 100  
24VAC Thermostat Input /  
Output  
W1  
24VAC input / output from indoor thermostat to indoor unit.  
C
24VAC Common  
Thermostat Service Light  
24VAC  
24VAC common  
L
Thermostat service light connection.  
24VAC  
P2  
R
Y2  
O
Thermostat Input  
Thermostat Input  
Thermostat Input  
Controls the second stage operation of the unit.  
Reversing valve solenoid.  
Controls the operation of the unit.  
Y1  
Low Ambient Thermostat Provides selection of the Y2 compressor lock−in temperature. Valid  
options are 40, 45, 50 and 55 degrees Fahrenheit.  
P3  
P4  
55, 50, 45, 40  
DIS−YEL  
Pins  
(P4−5) Ground connection for outdoor coil temperature sensor.  
(P4−6) Connection for outdoor coil temperature sensor.  
Coil Sensor  
(P4−3) Ground connection for outdoor ambient temperature sensor.  
(P4−4) Connection for outdoor ambient temperature sensor.  
AMB−BLACK  
Ambient Sensor  
COIL−BROWN  
Discharge Sensor  
No discharge sensor is used; replaced by 10K resistor.  
The demand defrost 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. When a jumper is installed on the DELAY pins, the  
compressor will be cycled off for 30 seconds going in and out of the  
defrost mode. Units are shipped with jumper installed on DELAY pins.  
P5  
DELAY  
Delay Mode  
NOTE The 30 second off cycle is NOT functional when TEST pins on  
P1 are jumpered.  
P6  
TST, PS DF, C, R, O, Y1, Y2  
RED LED  
Factory Test Connectors  
Diagnostic LED  
No field use.  
DS1  
Valid states for demand defrost control two LEDs are OFF, ON and  
FLASHING which indicate diagnostics conditions that are described in  
table 10.  
DS2  
GREEN LED  
TWO CONNECTORS  
O OUT  
FAN  
Condenser Fan Operation  
24 VAC output  
These two connections provide power for the condenser fan.  
24 VAC output connection for reversing valve.  
O OUT  
When the low pressure switch trips, the demand defrost control will cycle  
off the compressor, and the strike counter in the demand defrost control  
will count one strike. The low pressure switch is ignored under the  
following conditions:  
S
during the defrost cycle and 90 seconds after the termination of  
defrost  
LO−PS  
LO−PS  
Low−Pressure Switch  
S
S
S
when the average ambient sensor temperature is below 0°F (−18°C)  
for 90 seconds following the start up of the compressor  
during TEST mode  
Y2 OUT  
Y1 OUT  
Y2 OUT  
Y1 OUT  
24 VAC Output  
24 VAC output for second stage compressor solenoid.  
24 VAC Common Output  
24 VAC common output, switched for enabling compressor contactor.  
When the high pressure switch trips, the demand defrost control will cycle  
off the compressor, and the strike counter in the demand defrost control  
will count one strike.  
HS−PS  
HS−PS  
High−Pressure Switch  
L
L
Service Light Output  
24 Volt output  
24VAC service light output.  
24VAC typically used to supply power to the Lennox System Operation  
Monitor (LSOM). Not used in this system.  
24V  
24V  
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DEMAND DEFROST CONTROL (A108) DIAGNOSTIC LEDS  
The state (Off, On, Flashing) of two LEDs on the demand defrost control (DS1 [Red] and DS2 [Green]) indicate diagnostics  
conditions that are described in table 10.  
Table 10. Demand Defrost Control (A108) Diagnostic LEDs  
DS1 and DS2 System Status, Fault and Lockout Codes  
DS2  
Green  
DS1  
Red  
Condition/Code  
Possible Cause(s)  
Solution  
Type  
1
Check control transformer power (24V).  
If power is available to demand defrost con-  
No power (24V) to demand  
defrost control terminals R and C  
or demand defrost control failure.  
2
OFF  
OFF  
Status  
Power problem  
trol and LED(s) do not light, replace demand  
defrost control.  
Simultaneous  
SLOW Flash  
Unit operating normally or in  
standby mode.  
Status  
Status  
Normal operation  
None required.  
Alternating SLOW  
Flash  
Initial power up, safety trip, end of  
room thermostat demand.  
5−minuteanti−short cycle delay  
None required (jumper TEST pins to override)  
Sensor being detected open or shorted or out of temperature range. Demand defrost  
control will revert to time/temperature defrost operation. (System will still heat or  
cool).  
Simultaneous  
FAST Flash  
Fault  
Fault  
Fault  
Ambient Sensor Problem  
Coil Sensor Problem  
Sensor being detected open or shorted or out of temperature range. Demand defrost  
control will not perform demand or time/temperature defrost operation. (System will  
still heat or cool).  
Alternating  
FAST Flash  
Indicates that demand defrost control has internal component failure. Cycle 24VAC  
power to demand defrost control. If code does not clear, replace demand defrost  
control.  
Demand Defrost Control  
Failure  
ON  
ON  
1
Remove any blockages or restrictions from  
coils and/or fans. Check indoor and outdoor  
fan motor for proper current draws.  
SLOW  
Flash  
1
OFF  
OFF  
Fault  
Low Pressure Fault  
Low Pressure Lockout  
High Pressure Fault  
High Pressure Lockout  
Restricted air flow over indoor or  
outdoor coil.  
2
3
2
3
Improper refrigerant charge in  
system.  
Check system charge using subcooling  
method.  
ON  
Lockout  
Fault  
Improper metering device  
installed or incorrect operation  
of metering device.  
Check system operating pressures and  
compare to unit subcooling tables in this  
instruction or located on unit access panel.  
SLOW  
Flash  
OFF  
4
4
Incorrect or improper sensor  
location or connection to  
system.  
Make sure all pressure switches and sensors  
have secure connections to system to prevent  
refrigerant leaks or errors in pressure and  
temperaturemeasurements.  
ON  
OFF  
ON  
Lockout  
Fault  
SLOW  
Flash  
Discharge Line Temperature  
Fault  
This code detects shorted sensor or high discharge temperatures. If the discharge  
line temperature exceeds a temperature of 285ºF (140ºC) during compressor  
operation, the demand defrost control will de−energize the compressor contactor  
output (and the defrost output if active). The compressor will remain off until the  
discharge temperature has dropped below 225ºF (107ºC).  
FAST  
Flash  
Discharge Line Temperature  
Lockout  
ON  
Lockout  
Fault  
Fast  
Flash  
The demand defrost control detects open sensor or out of temperature sensor range.  
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  
demanddefrost control will count one fault. After 5 faults, the demand defrost control  
will lockout.  
OFF  
Discharge Sensor Fault  
Fast  
Flash  
Discharge Sensor Lockout  
OFF  
Lockout  
(Each fault adds 1 strike to that code’s counter; 5 strikes per code = LOCKOUT)  
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High Pressure Switch (S4)  
2. If the demand defrost control recognizes five  
temperature sensor range faults during a single (Y1)  
compressor demand, it reverts to a lockout mode and  
displays the appropriate code. The demand defrost  
control detects open sensor or out-of-temperature  
sensor range. 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 demand defrost control will count  
one fault. After five faults, the demand defrost control  
will lockout. Code on demand defrost control is  
Discharge Sensor Fault and Lockout.  
When the high pressure switch trips, the demand defrost  
control will cycle off the compressor, and the strike counter  
in the demand defrost control will count one strike. High  
Pressure (auto reset) − trip at 590 psig, reset at 418.  
Low Pressure Switch (S87)  
When the low pressure switch trips, the demand defrost  
control will cycle off the compressor, and the strike counter  
in the demand defrost control will count one strike. Low  
pressure switch (auto reset) − trip at 25 psig, reset at 40  
psig.  
The low pressure switch is ignored under the following  
conditions:  
The discharge line sensor, which covers a range of 150°F  
(65°C) to 350°F (176°C), is designed to mount on a ½"  
refrigerant discharge line.  
S
S
S
S
During the defrost cycle and 90 seconds after the  
termination of defrost  
NOTE − Within a single room thermostat demand, if  
5−strikes occur, the demand defrost control will lockout the  
unit. demand defrost control 24 volt power R must be  
cycled OFF or the TEST pins on demand defrost control  
must be shorted between 1 to 2 seconds to reset the  
demand defrost control.  
When the average ambient sensor temperature is  
below 15° F (−9°C)  
For 90 seconds following the start up of the  
compressor  
During test mode  
Crankcase Heater (HR1) and Crankcase Thermostat  
Switch (S40)  
Ambient Sensor (RT13)  
The ambient sensor 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 demand  
defrost control will not perform demand defrost operation.  
The demand defrost control will revert to time/temperature  
defrost operation and will display the appropriate fault  
code. Heating and cooling operation will be allowed in this  
fault condition.  
The reference models are equipped with a 70 watt, belly  
band type crankcase heater. HR1 prevents liquid from  
accumulating in the compressor. HR1 is controlled by a  
thermostat located on the liquid line. When liquid line  
temperature drops below 50° F the thermostat closes  
energizing HR1. The thermostat will open, de−energizing  
HR1 once liquid line temperature reaches 70° F .  
Liquid Line Bi−Flow Filter Drier  
The unit is equipped with a large−capacity biflow filter drier  
which keeps the system clean and dry. If replacement is  
necessary, order another of like design and capacity. The  
replacement filter drier must be suitable for use with  
HFC−410A refrigerant.  
Coil Sensor (RT21)  
Coil SensorꢀThe coil temperature sensor considers  
outdoor temperatures below −35°F (−37°C) or above 120°F  
(48°C) as a fault. If the coil temperature sensor is detected  
as being open, shorted or out of the temperature range of  
the sensor, the demand defrost 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.  
The replacement filter drier must be suitable for use with  
HFC−410A refrigerant.  
SECOND−STAGE OPERATION  
If the demand defrost control (A108) 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.  
High Discharge Temperature Sensor (RT28)  
If the discharge line temperature exceeds a temperature of  
285°F (140°C) during compressor operation, the demand  
defrost control will de−energize the compressor contactor  
output (and the defrost output, if active). The compressor  
will remain off until the discharge temperature has dropped  
below 225°F (107°C) and the 5-minute anti−short cycle  
delay has been satisfied. This sensor has two fault and  
lockout codes:  
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 without the  
Y2 input. If the jumper is not connected to one of the  
temperature selection pins on P3 (40, 45, 50, 55°F), the  
default lock−in temperature of 40°F (4.5°C) will be used.  
1. If the demand defrost control recognizes five high  
discharge line temperature faults during a single (Y1)  
compressor demand, it reverts to a lockout mode and  
displays the appropriate code. This code detects  
shorted sensor or high discharge temperatures. Code  
on demand defrost control is Discharge Line  
Temperature Fault and Lockout.  
The demand defrost control de−energizes the  
second-stage compressor solenoid output immediately  
when the Y2 signal 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.  
Page 33  
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If a pressure switch opens while the Y1 Out line is  
engaged, a 5−minute short cycle will occur after the switch  
closes.  
Defrost System  
This section addresses:  
S
S
S
Emergency Heat  
Demand Defrost Control Pressure Switch  
Connections  
Defrost System Overview  
The unit’s automatic reset pressure switches (LO PS − S87  
and HI PS − S4) are factory−wired into the demand defrost  
control on the LO−PS and HI−PS terminals, respectively.  
Defrost Control Connections, Jumper Settings and  
Features  
S
S
Operational Mode Overview (Calibration, Normal and  
Defrost)  
Demand Defrost Control Sensors  
Sensors connect to the demand defrost control through a  
field-replaceable harness assembly that plugs into the  
the sensors, the demand defrost control detects outdoor  
ambient, coil, and discharge temperature fault conditions.  
As the detected temperature changes, the resistance  
across the sensor changes.  
Defrost Cycle Actuation  
EMERGENCY HEAT (AMBER LIGHT)  
An emergency heat function is designed into some room  
thermostats. This feature is applicable when isolation of the  
outdoor unit is required, or when auxiliary electric heat is  
staged by outdoor thermostats. When the room thermostat is  
placed in the emergency heat position, the outdoor unit  
control circuit is isolated from power and field-provided relays  
bypass the outdoor thermostats. An amber indicating light  
simultaneously comes on to remind the homeowner that he  
is operating in the emergency heat mode.  
Testing Demand Defrost Control Sensors  
Sensor resistance values can be checked by ohming  
across pins shown in table 11.  
Table 11. Sensor Temperature /Resistance Range  
Emergency heat is usually used during an outdoor unit  
shutdown, but it should also be used following a power  
outage if power has been off for over an hour and the  
outdoor temperature is below 50°F (10°C). System should  
be left in the emergency heat mode at least six hours to  
allow the crankcase heater sufficient time to prevent  
compressor slugging.  
Pins/W  
ire  
Color  
Temperature  
Range °F (°C)  
Resistance values  
range (ohms)  
Sensor  
Outdoor  
−35 (−37) to 120 (48) 280,000 to 3750  
3 & 4  
(Black)  
Coil  
−35 (−37) to 120 (48) 280,000 to 3750  
5 & 6  
(Brown)  
DEFROST SYSTEM OVERVIEW  
Discharge (if 24 (−4) to 350 (176) 41,000 to 103  
applicable)  
1 & 2  
(Yellow)  
The control monitors ambient temperature, outdoor coil  
temperature, and total run time to determine when a  
defrost cycle is required. The coil temperature probe is  
designed withaspringcliptoallowmountingto theoutside  
coil tubing. The location of the coil sensor is important for  
proper defrost operation.  
Note: Sensor resistance increases as sensed temperature decreases.  
Tables 12 and 13 shows how the resistance varies as the  
temperature changes for various types of sensors.  
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 11, 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.  
NOTE − The demand defrost 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 demand defrost control initiates  
defrost cycles.  
Defrost Temperature Termination Jumper  
Settings (P1)  
DEFROST CONTROL CONNECTIONS, JUMPERS  
SETTINGS AND FEATURES  
The demand defrost control selections are: 50, 70, 90, and  
100°F (10, 21, 32 and 38°C). The shunt termination pin is  
factory set at 50°F (10°C). If temperature shunt is not  
installed, default termination temperature is 90°F (32°C).  
Pressure Switch 5−Strike Lockout  
The internal control logic of the demand defrost control  
counts the pressure switch trips only while the Y1 (Input)  
line is active. If a pressure switch opens and closes four  
times during a Y1 (Input), the control logic will reset the  
pressure switch trip counter to zero at the end of the Y1  
(Input). If the pressure switch opens for a fifth time during  
the current Y1 (Input), the control will enter a lockout  
condition.  
Test Pins (P1) Function  
Placing the jumper on the field test pins (P1) allows the  
technician to:  
S
S
S
S
Clear short cycle lockout  
Clear five−strike fault lockout  
The 5−strike pressure switch lockout condition can be reset  
by cycling OFF the 24−volt power to the demand defrost  
control or by shorting the TEST pins between 1 to 2  
seconds. All timer functions (run times) will also be reset.  
Cycle the unit in and out of defrost mode  
Place the unit in defrost mode to clear the coil  
See figure 27 for flowchart of test pin (P1) operations.  
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Compressor Delay Mode (P5)  
1. Frost Detection ꢀ If the compressor runs longer than  
30 minutes and the actual difference between the clear  
coil and frosted coil temperatures exceeds the  
maximum difference allowed by the demand defrost  
control, a defrost cycle will be initiated.  
The demand defrost 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. When a jumper is  
installed on the DELAY pins, the compressor will be cycled  
off for 30 seconds going in and out of the defrost mode.  
Units are shipped with jumper installed on DELAY pins.  
2. Time ꢀ If six hours of heating mode compressor run  
time has elapsed since the last defrost cycle while the  
coil temperature remains below 35°F (2°C), the  
demand defrost control will initiate a defrost cycle.  
NOTE − The 30 second off cycle is NOT functional when  
jumpering the TEST pins.  
OPERATIONAL MODE OVERVIEW  
The demand defrost control has three basic operational  
modes. Those modes are:  
Actuation  
When the reversing valve is de−energized, the Y1 circuit is  
energized, and the coil temperature is below 35°F (2°C),  
the demand defrost control logs the compressor run time.  
If the demand defrost control is not calibrated, a defrost  
cycle will be initiated after 30 minutes of heating mode  
compressor run time. The control will attempt to  
self−calibrate after this (and all other) defrost cycle(s).  
1. Calibration Mode ꢀ The demand defrost control is  
considered uncalibrated when power is applied to the  
demand defrost control, after cool mode operation, or  
if the coil temperature exceeds the termination  
further details).  
Calibration success depends on stable system  
temperatures during the 20−minute calibration period. If  
the demand defrost control fails to calibrate, another  
defrost cycle will be initiated after 45 minutes of heating  
mode compressor run time. Once the demand defrost  
control is calibrated, it initiates a demand defrost cycle  
when the difference between the clear coil and frosted coil  
temperatures exceeds the maximum difference allowed  
by the control or after six hours of heating mode  
compressor run time has been logged since the last  
defrost cycle.  
2. Normal Mode ꢀ The demand defrost control  
monitors the O line, to determine the system operating  
mode (heat/cool), outdoor ambient temperature, coil  
temperature (outdoor coil) and compressor run time to  
determine when a defrost cycle is required.  
Calibration of the demand defrost control occurs after  
a defrost cycle to ensure that there is no ice on the coil.  
During calibration, the temperature of both the coil and  
the ambient sensor are measured to establish the  
temperature differential which is required to allow a  
defrost cycle.  
Termination  
3. Defrost Mode ꢀ The following paragraphs provide a  
detailed description of the defrost system operation.  
The defrost cycle ends when the coil temperature exceeds  
the termination temperature or after 14 minutes of defrost  
operation. If the defrost is terminated by the 14−minute  
timer, another defrost cycle will be initiated after 30  
minutes of run time.  
DEFROST CYCLE ACTUATION  
The demand defrost control initiates a defrost cycle based  
on either frost detection or time.  
Page 35  
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DEFROST CONTROL (A108) CALIBRATION MODE SEQUENCE  
Occurs after power up and cooling operation, or if the coil temperature exceeds  
the termination temperature while in Heat Mode.  
Demand defrost control defaults to 30 minute ꢀ Time / Temperature Mode  
Reset Compressor Runtime / Reset Three / Five Strike Counter  
DEMAND MODE  
THIRTY (30) MINUTE TIME /  
TEMPERATURE MODE  
45 MINUTE  
TIME/TEMPERATURE MODE  
Accumulate compressor runtime of  
more than 30 minutes while coil  
temperature is below 35° F (2°C).  
When the accumulated compressor  
time exceeds six (6) hours or if the  
coil sensor indicates frost is present  
on coil, go to Defrost.  
Accumulate compressor runtime  
while coil temperature is below 35° F  
(2°C). When the accumulated  
compressor time exceeds 30 minutes  
go to Defrost.  
Accumulate compressor runtime  
while coil temperature is below 35°  
F (2°C). When the accumulated  
compressor time exceeds 45  
minutes go to Defrost.  
DEFROST  
S
S
S
Outdoor Fan OFF  
Reversing Valve ON  
W1 line ON  
Monitor coil temperature and  
time in defrost mode.  
HOW DID DEFROST TERMINATE?  
Defrosted for 14−minute without the coil temperature  
going above 35°F (2°C) for four (4) minutes and coil  
did not reach termination temperature.  
Coil temperature was above 35°F (2°C) for four (4)  
minutes. of the 14−minute defrost OR reached  
defrost termination temperature.  
DEFROST TERMINATION  
DEFROST TERMINATION  
S
S
S
S
Compressor runtime counter RESET  
Outdoor Fan ON  
S
S
S
S
Compressor runtime counter RESET  
Outdoor Fan ON  
Reversing Valve OFF  
W1 line OFF  
Reversing Valve OFF  
W1 line OFF  
Attempt to Calibration Temperature measurements are not taken for the first few minutes of each heat demand. This is  
to allow coil temperatures to stabilize. demand defrost control has a maximum of 20 minutes of accumulated compressor  
runtime in heat mode to calibrate demand defrost control This may involve more than one heating demand.  
NO ꢀ Demand defrost control  
reverts to 45 minute time  
temperature.  
Was stable coil temperature attained  
within 20 minutes?  
/
YES ꢀ Calibration occurred  
Figure 26. Defrost Calibration  
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Table 12. Ambient (RT13) and Coil (RT21) Sensors Temperature / Resistance Range  
Degrees  
Fahrenheit  
Degrees  
Fahrenheit  
Degrees  
Fahrenheit  
Degrees  
Fahrenheit  
Resistance  
Resistance  
Resistance  
Resistance  
136.3  
133.1  
130.1  
127.3  
124.7  
122.1  
119.7  
117.5  
115.3  
113.2  
111.2  
109.3  
107.4  
105.6  
103.9  
102.3  
100.6  
99.1  
97.6  
96.1  
94.7  
93.3  
92.0  
90.6  
89.4  
88.1  
86.9  
85.7  
84.5  
83.4  
82.3  
81.2  
80.1  
79.0  
78.0  
77.0  
76.0  
75.0  
74.1  
73.1  
72.2  
71.3  
70.4  
69.5  
68.6  
67.7  
66.9  
66.0  
65.2  
64.4  
63.6  
62.8  
62.0  
61.2  
60.5  
59.7  
59.0  
58.2  
57.5  
2680  
2859  
56.8  
56.0  
55.3  
54.6  
53.9  
53.2  
52.5  
51.9  
51.2  
50.5  
49.9  
49.2  
48.5  
47.9  
47.3  
46.6  
46.0  
45.4  
44.7  
44.1  
43.5  
42.9  
42.3  
41.7  
41.1  
40.5  
39.9  
39.3  
38.7  
38.1  
37.5  
37.0  
36.4  
35.8  
35.2  
34.7  
34.1  
33.5  
33.0  
32.4  
31.9  
31.3  
30.7  
30.2  
29.6  
29.1  
28.6  
28.0  
27.5  
26.9  
26.4  
25.8  
25.3  
24.8  
24.2  
23.7  
23.2  
22.6  
22.1  
16657  
16973  
17293  
17616  
17942  
18273  
18607  
18945  
19287  
19633  
19982  
20336  
20695  
21057  
21424  
21795  
22171  
22551  
22936  
23326  
23720  
24120  
24525  
24934  
25349  
25769  
26195  
26626  
27063  
27505  
27954  
28408  
28868  
29335  
29808  
30288  
30774  
31267  
31766  
32273  
32787  
33309  
33837  
34374  
34918  
35471  
36031  
36600  
37177  
37764  
38359  
38963  
39577  
40200  
40833  
41476  
42130  
42794  
43468  
21.6  
21.0  
20.5  
20.0  
19.4  
18.9  
18.4  
17.8  
17.3  
16.8  
16.3  
15.7  
15.2  
14.7  
14.1  
13.6  
13.1  
12.5  
12.0  
11.5  
11.0  
10.4  
9.9  
44154  
44851  
45560  
46281  
47014  
47759  
48517  
49289  
50074  
50873  
51686  
52514  
53356  
54215  
55089  
55979  
56887  
57811  
58754  
59715  
60694  
61693  
62712  
63752  
64812  
65895  
67000  
68128  
69281  
70458  
71661  
72890  
74147  
75431  
76745  
78090  
79465  
80873  
82314  
83790  
85302  
86852  
88440  
90068  
91738  
93452  
95211  
97016  
98870  
100775  
102733  
104746  
106817  
108948  
111141  
113400  
115727  
118126  
120600  
−11.3  
−11.9  
−12.6  
−13.2  
−13.9  
−14.5  
−15.2  
−15.9  
−16.5  
−17.2  
−17.9  
−18.6  
−19.3  
−20.1  
−20.8  
−21.5  
−22.3  
−23.0  
−23.8  
−24.6  
−25.4  
−26.2  
−27.0  
−27.8  
−28.7  
−29.5  
−30.4  
−31.3  
−32.2  
−33.2  
−34.1  
−35.1  
−36.1  
−37.1  
−38.2  
−39.2  
123152  
125787  
128508  
131320  
134227  
137234  
140347  
143571  
146913  
150378  
153974  
157708  
161588  
165624  
169824  
174200  
178762  
183522  
188493  
193691  
199130  
204829  
210805  
217080  
223677  
230621  
237941  
245667  
253834  
262482  
271655  
281400  
291774  
302840  
314669  
327343  
3040  
3223  
3407  
3592  
3779  
3968  
4159  
4351  
4544  
4740  
4937  
5136  
5336  
5539  
5743  
5949  
6157  
6367  
6578  
6792  
7007  
7225  
9.3  
7444  
8.8  
7666  
8.3  
7890  
7.7  
8115  
7.2  
8343  
6.7  
8573  
6.1  
8806  
5.6  
9040  
5.0  
9277  
4.5  
9516  
3.9  
9757  
3.4  
10001  
10247  
10496  
10747  
11000  
11256  
11515  
11776  
12040  
12306  
12575  
12847  
13122  
13400  
13681  
13964  
14251  
14540  
14833  
15129  
15428  
15730  
16036  
16345  
2.8  
2.3  
1.7  
1.2  
0.6  
0.0  
−0.5  
−1.1  
−1.7  
−2.2  
−2.8  
−3.4  
−4.0  
−4.6  
−5.2  
−5.7  
−6.3  
−6.9  
−7.5  
−8.2  
−8.8  
−9.4  
−10.0  
−10.6  
Page 37  
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Table 13. High Discharge Sensor (RT28) Temperature / Resistance Range  
Degrees  
Fahrenheit  
Degrees  
Fahrenheit  
Degrees  
Fahrenheit  
Degrees  
Fahrenheit  
Resistance  
Resistance  
Resistance  
Resistance  
303.1  
298.1  
293.4  
289.0  
284.8  
280.9  
277.1  
273.6  
270.2  
267.0  
263.9  
260.9  
258.1  
255.3  
252.7  
250.1  
247.7  
245.3  
243.0  
240.8  
238.6  
236.5  
234.4  
232.4  
230.5  
228.6  
226.7  
224.9  
223.2  
221.5  
219.8  
218.1  
216.5  
214.9  
213.4  
211.9  
210.4  
208.9  
207.5  
206.0  
204.6  
203.3  
201.9  
200.6  
199.3  
198.0  
196.8  
195.5  
194.3  
193.1  
191.9  
190.7  
189.5  
188.4  
187.2  
183  
195  
207  
220  
232  
245  
258  
270  
283  
297  
310  
323  
336  
350  
364  
378  
391  
405  
420  
434  
448  
463  
478  
492  
507  
523  
538  
553  
569  
584  
600  
616  
632  
649  
665  
682  
698  
715  
732  
750  
767  
785  
803  
821  
839  
857  
876  
894  
913  
932  
952  
971  
991  
1011  
1031  
186.1  
185.0  
183.9  
182.8  
181.8  
180.7  
179.6  
178.6  
177.6  
176.6  
175.5  
174.6  
173.6  
172.6  
171.6  
170.6  
169.7  
168.7  
167.8  
166.9  
165.9  
165.0  
164.1  
163.2  
162.3  
161.4  
160.5  
159.7  
158.8  
157.9  
157.1  
156.2  
155.3  
154.5  
153.6  
152.8  
152.0  
151.1  
150.3  
149.5  
148.7  
147.9  
147.1  
146.2  
145.4  
144.6  
143.8  
143.0  
142.3  
141.5  
140.7  
139.9  
139.1  
138.3  
137.6  
1052  
1072  
1093  
1114  
1135  
1157  
1179  
1201  
1223  
1245  
1268  
1291  
1315  
1338  
1362  
1386  
1411  
1435  
1460  
1486  
1511  
1537  
1563  
1590  
1617  
1644  
1672  
1699  
1728  
1756  
1785  
1815  
1845  
1875  
1905  
1936  
1968  
1999  
2032  
2064  
2098  
2131  
2165  
2200  
2235  
2270  
2306  
2343  
2380  
2418  
2456  
2495  
2534  
2574  
2615  
136.8  
136.0  
135.2  
134.5  
133.7  
132.9  
132.2  
131.4  
130.6  
129.9  
129.1  
128.4  
127.6  
126.8  
126.1  
125.3  
124.6  
123.8  
123.1  
122.3  
121.6  
120.8  
120.1  
119.3  
118.5  
117.8  
117.0  
116.3  
115.5  
114.8  
114.0  
113.2  
112.5  
111.7  
111.0  
110.2  
109.4  
108.7  
107.9  
107.1  
106.4  
105.6  
104.8  
104.0  
103.3  
102.5  
101.7  
100.9  
100.1  
99.3  
2656  
2698  
2740  
2783  
2827  
2872  
2917  
2963  
3010  
3057  
3105  
3154  
3204  
3255  
3307  
3359  
3413  
3467  
3523  
3579  
3637  
3695  
3755  
3816  
3877  
3940  
4005  
4070  
4137  
4205  
4274  
4345  
4418  
4491  
4567  
4644  
4722  
4802  
4884  
4968  
5054  
5141  
5231  
5323  
5416  
5512  
5610  
5711  
5814  
5920  
6028  
6139  
6253  
6370  
6489  
94.5  
93.6  
92.8  
92.0  
91.2  
90.3  
89.5  
88.6  
87.8  
86.9  
86.0  
85.2  
84.3  
83.4  
82.5  
81.6  
80.7  
79.8  
78.8  
77.9  
76.9  
76.0  
75.0  
74.1  
73.1  
72.1  
71.1  
70.0  
69.0  
68.0  
66.9  
65.8  
64.7  
63.6  
62.5  
61.3  
60.2  
59.0  
57.8  
56.6  
55.3  
54.0  
52.7  
51.4  
50.0  
48.6  
47.2  
45.7  
6613  
6739  
6869  
7002  
7139  
7281  
7426  
7575  
7729  
7888  
8051  
8220  
8394  
8574  
8759  
8951  
9149  
9354  
9566  
9786  
10013  
10250  
10495  
10749  
11014  
11289  
11575  
11873  
12184  
12509  
12848  
13202  
13573  
13961  
14368  
14796  
15246  
15719  
16218  
16744  
17301  
17891  
18516  
19180  
19887  
20641  
21448  
22311  
98.5  
97.7  
96.9  
96.1  
95.3  
Page 38  
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TEST  
PSlacing the jumper on the field test pins (P1) allows the technician to:  
Clear short cycle lockout  
S
S
S
Clear five−strike fault lockout  
Cycle the unit in and out of defrost mode  
Place the unit in defrost mode to clear the coil  
WhenY1 is energized and 24V power is being applied to the Control, a test cycle can be initiated by placing a jumper on the Control’s TEST pins for 2 to  
5 seconds. If the jumper remains on the TEST pins for longer than five seconds, the Control will ignore the jumpered TEST pins and revert to normal  
operation.  
The 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.  
Place a jumper on TEST pins for  
more than two seconds.  
Clears any short cycle lockout and  
five strike fault lockout function, if  
applicable.  
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.  
ACTIVE  
INACTIVE  
O Line Status  
If in HEATING Mode  
If in COOLING Mode  
If in DEFROST Mode  
The unit will terminate defrost and  
enter HEAT MODE uncalibrated  
with defrost timer set for 45 minute  
test.  
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.  
If jumper on TEST pins remains in  
place for more than five seconds.  
If jumper on TEST pins is removed  
before a maximum of five seconds.  
NOTE ꢀ Placing a jumper on the TEST pins will not bring the unit  
out of inactive mode. The only way manually activate the heat  
pump from an inactive mode is to cycle the 24VAC power to the  
Control.  
The unit will remain in DEFROST  
MODE until termination on time or  
temperature.  
The unit will return to HEAT MODE  
uncalibrated with defrost timer set  
for 34 minutes.  
Figure 27. Test Pin (P1) Functions  
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12. After testing is complete, return unit to original set up.  
Two−Stage Modulation Compressors  
Checks  
Maintenance  
DEALER  
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:  
Use this checklist on page 42 to verify part-load and  
full-load capacity operation of two-stage modulation  
compressors.  
TOOLS REQUIRED  
S
S
S
S
Refrigeration gauge set  
Digital volt/amp meter  
Outdoor Unit  
1. Clean and inspect outdoor coil (may be flushed with a  
water hose). Ensure power is off before cleaning.  
Electronic temperature thermometer  
On-off toggle switch  
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.  
IMPORTANT  
4. Check all wiring for loose connections.  
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).  
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.  
PROCEDURE  
NOTE − Block outdoor coil to maintain a minimum of 375  
psig during testing).  
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)  
1. Turn main power OFF to outdoor unit.  
2. Adjust room thermostat set point 5ºF above 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.  
S
S
Outdoor Coil ꢀ The outdoor coil may be flushed with  
a water hose.  
Outdoor Coil (Sea Coast) ꢀ Moist air in ocean  
locations can carry salt, which is corrosive to most  
metal. Units that are located near the ocean require  
frequent inspections and maintenance. These  
inspections 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.  
4. Turn toggle switch OFF and install switch in series with  
Y2 wire from room thermostat.  
5. Cycle main power ON.  
6. Allow pressures and temperatures to stabilize before  
taking measurements (may take up to 10 minutes).  
7. Record all of the readings for the Y1 demand.  
Indoor Unit  
1. Clean or change filters.  
8. Close switch to energize Y2 demand. Verify power is  
going to compressor solenoid.  
2. Lennox blower motors are prelubricated and  
permanently sealed. No more lubrication is needed.  
9. Allow pressures and temperatures to stabilize before  
taking measurements (may take up to 10 minutes).  
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.  
10. Record all of the readings with the Y1 and Y2 demand.  
11. If temperatures and pressures change in the direction  
noted in Two−Stage Modulation Compressor Field  
Operational Checklist on page 42, 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 modulating between low and high capacity and  
replacement is necessary).  
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:__________.  
Page 40  
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Indoor Coil  
1. Clean coil if necessary.  
filter to dry completely before returning it to the unit or  
grille.  
2. Check connecting lines, joints and coil for evidence of  
oil leaks.  
NOTE The filter and all access panels must be in place  
any time the unit is in operation.  
4. Indoor Unit ꢀ The indoor unit’s evaporator coil is  
equipped with a drain pan to collect condensate  
formed as your system removes humidity from the  
inside air. Have your dealer show you the location of  
the drain line and how to check for obstructions. (This  
would also apply to an auxiliary drain, if installed.)  
3. Check condensate line and clean if necessary.  
HOMEOWNER  
Cleaning of the outdoor unit’s coil should be performed by  
a trained service technician. Contact your dealer and set  
up a schedule (preferably twice a year, but at least once a  
year) to inspect and service your outdoor unit. The  
following maintenance may be performed by the  
homeowner.  
Thermostat Operation  
See the thermostat homeowner manual for instructions on  
how to operate your thermostat.  
Heat Pump Operation  
Your new Lennox heat pump has several characteristics  
that you should be aware of:  
IMPORTANT  
Sprinklers and soaker hoses should not be installed  
where they could cause prolonged exposure to the  
outdoor unit by treated water. Prolonged exposure of the  
unit to treated water (i.e., sprinkler systems, soakers,  
waste water, etc.) will corrode the surface of steel and  
aluminum parts and diminish performance and longevity  
of the unit.  
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Heat pumps satisfy heating demand by delivering  
large amounts of warm air into the living space. This  
is quite different from gas- or oil-fired furnaces or an  
electric furnace which deliver lower volumes of  
considerably hotter air to heat the space.  
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Do not be alarmed if you notice frost on the outdoor coil  
in the winter months. Frost develops on the outdoor  
coil during the heating cycle when temperatures are  
below 45F (7C). An electronic control activates a  
defrost cycle lasting 5 to 15 minutes at preset intervals  
to clear the outdoor coil of the frost.  
Outdoor Coil  
The outdoor unit must be properly maintained to ensure its  
proper operation.  
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Please contact your dealer to schedule proper  
inspection and maintenance for your equipment.  
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During the defrost cycle, you may notice steam rising  
from the outdoor unit. This is a normal occurrence. The  
thermostat may engage auxiliary heat during the  
defrost cycle to satisfy a heating demand; however,  
the unit will return to normal operation at the  
conclusion of the defrost cycle.  
Make sure no obstructions restrict airflow to the  
outdoor unit.  
Grass clippings, leaves, or shrubs crowding the unit  
can cause the unit to work harder and use more  
energy.  
Extended Power Outage  
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Keep shrubbery trimmed away from the unit and  
periodically check for debris which collects around the  
unit.  
The heat pump is equipped with a compressor crankcase  
heater which protects the compressor from refrigerant  
slugging during cold weather operation.  
Cleaning of the outdoor unit’s coil should be performed by  
a trained service technician. Contact your dealer and set  
up a schedule (preferably twice a year, but at least once a  
year) to inspect and service your outdoor unit.  
If power to your unit has been interrupted for several hours  
or more, set the room thermostat selector to the  
EMERGENCY HEAT setting to obtain temporary heat  
without the risk of serious damage to the heat pump.  
Routine Maintenance  
In EMERGENCY HEAT mode, all heating demand is  
satisfied by auxiliary heat; heat pump operation is locked  
out. After a six-hour compressor crankcase warm-up  
period, the thermostat can be switched to the HEAT setting  
and normal heat pump operation may resume.  
In order to ensure peak performance, your system must be  
properly maintained. Clogged filters and blocked airflow  
prevent your unit from operating at its most efficient level.  
1. Air Filter ꢀ Ask your Lennox dealer to show you  
where your indoor unit’s filter is located. It will be either  
at the indoor unit (installed internal or external to the  
cabinet) or behind a return air grille in the wall or  
ceiling. Check the filter monthly and clean or replace  
it as needed.  
Preservice Check  
If your system fails to operate, check the following before  
calling for service:  
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Verify room thermostat settings are correct.  
Verify that all electrical disconnect switches are ON.  
Check for any blown fuses or tripped circuit breakers.  
Verify unit access panels are in place.  
2. Disposable Filter ꢀ Disposable filters should be  
replaced with a filter of the same type and size.  
NOTE If you are unsure about the filter required for your  
system, call your Lennox dealer for assistance.  
Verify air filter is clean.  
3. Reusable Filter ꢀ Many indoor units are equipped  
with reusable foam filters. Clean foam filters with a  
mild soap and water solution; rinse thoroughly; allow  
If service is needed, locate and write down the unit  
model number and have it handy before calling.  
Page 41  
XP16 SERIES  
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Accessories  
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Lennox XP16 Engineering Handbook  
Lennox Product Catalog  
For update−to−date information, see any of the following  
publications:  
Lennox Price Book  
Checklists  
Two−Stage Modulation Compressors Field Operational Checklist  
Expected results during Y2 demand  
(Toggle switch On)  
Unit Readings  
Y1 − First-Stage  
Y2 − Second-Stage  
COMPRESSOR  
Voltage  
Same  
Amperage  
Higher  
OUTDOOR UNIT FAN MOTOR  
Amperage  
Same or Higher  
TEMPERATURE  
Ambient  
Same  
Higher  
Higher  
Same  
Lower  
Outdoor Coil Discharge Air  
Compressor Discharge Line  
Indoor Return Air  
Indoor Coil Discharge Air  
PRESSURES  
Suction (Vapor)  
Liquid  
Lower  
Higher  
Page 42  
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XP16 Start−Up and Performance  
Customer  
Address  
Serial  
Indoor Unit Model  
Outdoor Unit Model  
Notes:  
Serial  
START UP CHECKS  
RefrigerantType:  
1st Stage: Rated Load Amps  
2nd Stage: Rated Load Amps  
Outdoor Unit Fan Full Load Amps  
Actual Amps  
Actual Amps  
Rated Volts  
Actual Volts  
Actual Volts  
2nd Stage  
Rated Volts  
1st Stage  
Actual Amps:  
COOLING MODE  
Suction Pressure: 1st Stage:  
Liquid Pressure: 1st Stage:  
Supply Air Temperature: 1st Stage:  
Temperature: Ambient:  
2nd Stage:  
2nd Stage:  
2nd Stage:  
Return Air:  
System Refrigerant Charge (Refer to manufacturer’s information on unit or installation instructions for required subcooling and approach tempera-  
tures.)  
A
A
A
B
B
B
SUBCOOLING  
Subcooling:  
=
=
=
Saturated Condensing Temperature (A) minus Liquid  
Line Temperature (B)  
APPROACH  
Approach:  
Liquid Line Temperature (A) minus Outdoor Air  
Temperature (B)  
COIL TEMP DROP  
Indoor Coil Temperature Drop (18 to 22°F)  
Return Air Temperature (A) minus Supply Air  
Temperature (B)  
Page 43  
XP16 SERIES  
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