Lennox HP21 User manual

Page 1
504,437M
*P504437M*
02/04
*2P0204*
2001 Lennox Industries Inc.
Dallas, Texas, USA

HP21 Outdoor Unit
Lennox HP21 two−speed outdoor units are approved and
warranted only for installation with specially matched indoor
coils, line sets and thermal expansion valves (TXV) as des-
ignated by Lennox. Refer to the Lennox Engineering Hand-
book for approved systems.
Shipping and Packing List
1 − Assembled HP21 outdoor unit unit
Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.
General Information
These instructions are intended as a general guide and do
not supersede national or local codes in any way. Consult
authorities having jurisdiction before installation. Only quali-
fied technicians should install and service the unit.
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, person-
al injury or loss of life. Installation and service must
be performed by a qualified installer or service
agency.
IMPORTANT
The Clean Air Act of 1990 bans the intentional vent-
ing of refrigerant (CFC’s and HCFC’s) as of July 1,
1992. Approved methods of recovery, recycling or
reclaiming must be followed. Fines and/or incarcera-
tion may be levied for noncompliance.
INSTALLATION
INSTRUCTIONS
HP21 SERIES UNITS
HEAT PUMP UNITS
504,437M
02/04
Supersedes 12/02
Table of Contents
HP21 Outdoor Unit 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shipping and Packing List 1. . . . . . . . . . . . . . . . . . . . . . .
General Information 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts Arrangement 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Unit 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Refrigerant Piping 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Refrigerant Metering Device 11. . . . . . . . . . . . . . . . . . . .
Manifold Gauge Set 11. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Valves 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Leak Testing 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Evacuation 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Start−Up 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Charging 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Two−Speed Control (TSC6) 16. . . . . . . . . . . . . . . . . . . . .
System Operation 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defrost System 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Optional Accessories 22. . . . . . . . . . . . . . . . . . . . . . . . . .
HP21 Check Points 22. . . . . . . . . . . . . . . . . . . . . . . . . . . .
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE
WARNING
This product and/or the indoor unit it is matched with
may contain fiberglass wool
Disturbing the insulation during installation, mainte-
nance, or repair will expose you to fiberglass wool
dust. Breathing this may cause lung cancer. (Fiber-
glass wool is known to the State of California to
cause cancer.)
Fiberglass wool may also cause respiratory, skin,
and eye irritation.
To reduce exposure to this substance or for further
information, consult material safety data sheets
available from address shown below, or contact your
supervisor.
Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379−9900
Litho U.S.A.

2-3/4
(70)
4-1/2
(114)
COMPRESSOR
INLET AIR
INLET AIR
INLET
AIR
TOP VIEW
FRONT VIEWSIDE VIEW
ELECTRICAL
INLETS
VAPOR LINE
INLET
LIQUID LINE
INLET
DISCHARGE AIR
COIL DRAIN
OUTLETS
(Around perimeter
of base)
A
1-3/8
(35)
6-1/16
(154)
4
(102)
2-1/2
(64)
32-1/8
(816)
34-1/16
(865)
26-5/8 (676)
18-5/8 (473)
28-1/8
(714) 2−1/4 (57)
4
(102)
2-7/8
(73)
B
2−1/4 (57)
9−1/8
(232)
9−1/8
(232)
3−1/8
(79)
3−1/8
(79) 3−1/8
(79)
Page 2
Unit Dimensions − inches (mm)
Model
A B
Model
No. in. mm in. mm
HP21-36 34-7/8 886 16-3/4 425
HP21-48 40-7/8 1038 19-3/4 502
HP21-60 44-7/8 1140 19-3/4 502

Page 3
Parts Arrangement
Figure 1
HP21 Parts Arrangement
COMPRESSOR
TERMINAL BOX
COMPRESSOR
OUTDOOR
FAN
TRANSFORMER
LIQUID LINE
SERVICE VALVE
VAPOR LINE
SERVICE VALVE
UNIT CONTROL
BOX
HIGH PRESSURE
SWITCH
DISCHARGE LINE
MUFFLER
FILTER/DRIER
REVERSING
VALVE
Setting the Unit
CAUTION
In order to avoid injury, take proper precaution when
lifting heavy objects.
CAUTION
Sharp sheet metal edges can cause injury. When
installing the unit, avoid accidental contact with
sharp edges.
Outdoor units operate under a wide range of weather con-
ditions; therefore, several factors must be considered
when positioning the outdoor unit. The unit must be posi-
tioned to give adequate clearances for sufficient airflow
and servicing. A minimum clearance of 24 inches (610 mm)
between multiple units must be maintained. Refer to figure
2 for installation clearances.
36"
(914 mm) 36"
(914 mm)
*36"
(914 mm)
*36"
(914 mm)
Installation Clearances
Figure 2
NOTE − A service access
clearance of 30" (762 mm)
must be maintained in front
of the service access panel.
Clearance to one side must
be 36" (914 mm). Clearance
to one of the remaining two
sides may be 12" (304 mm)
and the final side may be 6"
(152 mm).
NOTE − A clearance of 24" (610 mm)
must be maintained between two units.
NOTE − 48" (1219 mm) clearance required on top
of unit. Maximum soffit overhang is 36" (914 mm).

Page 4
1 − Place a sound−absorbing material, such as Isomode,
under the unit if you plan to install it in a location or posi-
tion that will transmit sound or vibration to the living
area or adjacent buildings.
2 − Mount the unit high enough above ground or roof to al-
low adequate drainage of defrost water and to prevent
ice build−up.
3 − In heavy snow areas, do not locate the unit where snow
build−up will occur. The unit base should be elevated
above the depth of average snows.
NOTE − Construct a frame using suitable materials to
elevate the unit. If you construct a support frame, it
must not block the drain holes in the base of the unit.
4 − If the unit is installed in areas where low ambient tem-
peratures exist, locate the unit so that winter prevailing
winds do not blow directly into the outdoor coil.
5 − Locate the unit away from overhanging roof lines which
would allow water or ice to drop on, or in front of, the coil
or into the unit.
Slab Mounting − Figure 3
When installing the unit at grade level, the top of the slab
should be high enough above the grade so that water from
higher ground will not collect around the unit. See figure 3.
Slab should have a slope tolerance away from the building
of 2 degrees or 2 inches per 5 feet (51 mm per 1.5 m). This
will prevent ice build−up under the unit during a defrost
cycle. Refer to the next section (roof mounting) for barrier
construction if the unit must face prevailing winter winds.
2 degrees or
2 in. per 5 foot
(51 mm per 1.5 m)
slope tolerance away
from building structure
Slab Mounting
Figure 3
ground level
mounting
slab
building
structure
discharge air
Roof Mounting − Figure 4
Install the unit at least 4 inches above the surface of the roof.
The weight of the unit must be properly distributed over roof
joists and rafters. Use redwood or steel supports. Consult
local codes for rooftop applications.
If the unit coil cannot be mounted away from prevailing win-
ter winds, construct a wind barrier. The barrier must match
the size of the outdoor unit. Mount the barrier 36 inches
(914 mm) from the sides of the unit in the direction of pre-
vailing winds.
INLET AIR
INLET AIR
INLET
AIR
WIND BARRIER
PREVAILING WINTER WINDS
Rooftop Application
Wind Barrier Construction
Figure 4
36 in.
(914 mm)
Electrical
In the U.S.A., wiring must conform with current local codes
and the current National Electric Code (NEC). In Canada,
wiring must conform with current local codes and the current
Canadian Electrical Code (CEC).
Refer to the furnace or blower coil installation instructions
for additional wiring application diagrams and refer to unit
nameplate for minimum circuit ampacity and maximum
overcurrent protection size.
WARNING
Electric Shock Hazard. Unit must be grounded in ac-
cordance with national and local codes. Can cause
injury or death.
1 −Install line voltage power supply to unit from a properly
sized disconnect switch.
2 −Ground unit at unit disconnect switch or to an earth
ground.
NOTE − To facilitate conduit, a hole is in the bottom of
the control box. Connect conduit to the control box us
ing a proper conduit fitting.
NOTE − Units are approved for use only with copper
conductors.
24V, Class II circuit connections are made in the low
voltage junction box. Refer to figures 5 and 7 for field
wiring diagram.
NOTE − A complete unit wiring diagram is located in
side the unit control box cover.
3 − Install room thermostat (ordered separately) on an in-
side wall approximately in the center of the conditioned
area and 5 feet (1.5 m) from the floor. It should not be
installed on an outside wall or where it can be effected
by sunlight, drafts or vibrations.
4 − Install voltage wiring from outdoor to indoor unit and
from thermostat to indoor unit. See figure 7.

Page 5
HP21 Single Phase Typical Wiring Field Wiring Diagram
x
Figure 5
HP21 Three Phase Typical Wiring Field Wiring Diagram
x
Figure 6

Page 6
FIELD WIRING DIAGRAM HP21 WITH CB
24VAC 18GA. MIN.
6
6
Jumpers
Required
FIELD INSTALLED JUMPERS REQUIRED
FOR TERMINAL STRIP TB1
With CCB1
Humidity
Control
Without CCB1
Humidity
Control
Outdoor UnitHumidity
Control
Single-Speed Outdoor Unit Y1 to Y2
Two-Speed Outdoor Unit none
Single-Speed Outdoor Unit
Two-Speed Outdoor Unit
DS to Y1
DS to Y2
Figure 7
C
C
RGCT
T

Page 7
Refrigerant Piping
Field refrigerant piping consists of liquid and vapor lines
from the outdoor unit (sweat connections) to the indoor
evaporator coil (typically flare connections). Use Lennox
L15 line sets as shown in table 1 or use field−fabricated re-
frigerant lines. Refer to Refrigerant Piping Guide (Corp.
9351−L9) for proper size, type, and application of field−fab-
ricated lines. Valve sizes are also listed in table 1.
Table 1
Refrigerant Line Sets
Mdl
Valve Field Size
Connections Recommended Line Set
Model
Liquid
Line
Vapor
Line Liquid
Line
Vapor
Line
L15
Line Sets
−36 3/8 in.
(10 mm)
3/8 in.
(10 mm)
3/8 in.
(10 mm)
3/4 in.
(19 mm)
L15−41
15 ft − 50 ft
(4.6 m − 15 m)
−48
3/8 in.
(10 mm)
7/8 in.
(22 mm)
3/8 in.
(10 mm)
7/8 in.
(22 mm)
L15−65
15 ft− 50 ft
(4.6 m − 15 m)
−60
3/8 in.
(10 mm)
7/8 in.
(22 mm)
3/8 in.
(10 mm)
1−1/8 in.
(29 mm) Field
Fabricated
NOTE − Units are designed for line sets of up to 50 feet (15
m). For applications longer than 50 feet, consult the Len-
nox Refrigerant Piping Guide (Corp. 9351−L9).Select line
set diameters from table 1 to ensure that oil returns to the
compressor.
Installing Refrigerant Line
During the installation of any heat pump or a/c system, it is
important to properly isolate the refrigerant lines to prevent
unnecessary vibration. Line set contact with the structure
(wall, ceiling or floor) causes some objectionable noise
when vibration is translated into sound. As a result, more
energy or vibration can be expected. Closer attention to
line set isolation must be observed.
Following are some points to consider when placing and
installing a high−efficiency outdoor unit:
1- Placement − Be aware some localities are adopting
sound ordinances based on how noisy the unit is from
the adjacent property not at the original installation.
Install the unit as far as possible from the property line.
When possible, do not install the unit directly outside a
window. Glass has a very high level of sound transmis-
sion.
2- Line Set Isolation − The following illustrations demon-
strate procedures which ensure proper refrigerant line
set isolation. Figure 8 shows how to install line sets on
vertical runs. Figure 9 shows how to install line sets on
horizontal runs. Figure 10 shows how to make a transi-
tion from horizontal to vertical. Finally, figure 11 shows
how to place the outdoor unit and line set.

Page 8
Refrigerant Line Sets
How To Install Vertical Runs
(new construction shown)
PVC Pipe Fiberglass
Insulation
Caulk
Outside Wall
Vapor Line
(wrapped with Armaflex)
Liquid Line
IMPORTANT - Refrigerant
lines must not contact
structure.
Outside Wall
Inside Wall
Liquid LineVapor Line
IMPORTANT - Refrigerant
lines must not contact wall.
Wood Block
Between Studs
Strap
Sleeve
Wood Block
Strap
Sleeve
Wire Tie
Wire Tie
Wire Tie
NOTE - Similar installation practices should be used if
line set is to be installed on exterior of outside wall.
Figure 8

Page 9
Refrigerant Line Sets:
Installing Horizontal Runs
8 feet
8 feet
Metal Sleeve
Strapping Material (around vapor line only)
Tape or Wire Tie
Wire Tie
(around vapor line only)
Floor Joist or
Roof Rafter
Tape or Wire Tie
Strap the vapor line to the joist or rafter at 8 ft.
intervals then strap the liquid line to the vapor line.
To hang line set from joist or rafter,
use either metal strapping material
or anchored heavy nylon wire ties.
Floor Joist or Roof Rafter
Figure 9

Page 10
Refrigerant Line Sets:
Transition From Vertical To Horizontal
Liquid Line
Vapor Line
Wrapped in
Armaflex
Strap Liquid Line
To Vapor Line
Metal
Sleeve
Anchored Heavy
Nylon Wire Tie
Automotive
Muffler-Type
Hanger
Wall
Stud
Wall
Stud
Liquid Line
Vapor Line
Wrapped in
Armaflex
Strap Liquid Line
To Vapor Line
Metal
Sleeve
Figure 10
Outside Unit Placement and Installation
Install unit away from windows.
Two 90° elbows
installed in line set
will reduce line set
vibration.
Figure 11

Page 11
Brazing Connection Procedure
1 − Cut ends of the refrigerant lines square (free from nicks
or dents). Debur the ends. The pipe must remain
round, do not pinch end of the line.
2 − Before making line set connections, use dry nitrogen to
purge the refrigerant piping. This will help to prevent
oxidation and the introduction of moisture into the sys-
tem.
3 − Use silver alloy brazing rods (5 or 6 percent minimum
silver alloy for copper−to−copper brazing or 45 percent
silver alloy for copper−to−brass or copper−to−steel braz-
ing) which are rated for use with HCFC−22 refrigerant.
Wrap a wet cloth around the valve body and the copper
tube stub. Braze the line set to the service valve.
4 − Wrap a wet cloth around the valve body and copper
tube stub to protect it from heat damage during braz-
ing. Wrap another wet cloth underneath the valve body
to protect the base paint.
NOTE − The tube end must stay bottomed in the fitting
during final assembly to ensure proper seating, sealing
and rigidity.
5 − Install a field−provided thermal expansion valve (ap-
proved for use with HCFC−22 refrigerant) in the liquid
line at the indoor coil.
Refrigerant Metering Device
These units are used in check expansion valve systems
only. See the Lennox Engineering Handbook for approved
TXV match-ups and application information.
Check expansion valves equipped with Chatleff fittings
are available from Lennox. Refer to the Engineering
Handbook for applicable expansion valves for use with
specific match-ups.
If you install a check expansion valve with an indoor coil
that includes a fixed orifice, remove the orifice before
installing the check expansion valve.
See figure 12 for installation of the check expansion valve.
IMPORTANT
Failure to remove RFC orifice when installing an ex-
pansion valve on the indoor coil will result in improp-
er operation and damage to the system.
Metering Device Installation
expansion
valve
o−ring
o−ring
strainer
liquid line
stub
distributor
Figure 12
Manifold Gauge Set
Use a manifold gauge set equipped with low loss" hoses
when checking the charge of the unit. Do not use A man-
ifold gauge set with anything other than low loss" hose.
See figure 13.

Page 12
HP21 Cooling Cycle
(Shows Gauge Manifold Connections)
Figure 13
LOW
PRESSURE
HIGH
PRESSURE
COMPRESSOR
REVERSING
VALVE
Indoor Unit
Outdoor Unit
CHECK AND
EXPANSION
VALVE
VAPOR LINE
VALVE
LIQUID LINE
VALVE
ACCUMULATOR
LOW
PRESSURE
CONNECTION
HEATING
CYCLE
LOW
PRESSURE
CONNECTION
COOLING
CYCLE
CHARGE
COMPENSATOR
FILTER/DRIER
(BI−FLOW)
HIGH
PRESSURE
SWITCH
DISCHARGE
MUFFLER
CHECK AND
EXPANSION
VALVE
TO
REFRIGERANT
DRUM
OUTDOOR COIL
INDOOR COIL
Service Valves
The liquid line and vapor line service valves (figure 7) and
and gauge ports are used for leak testing, evacuating,
charging and checking charge. See table 2 for torque re-
quirements.
Each valve is equipped with a service port which has a fac-
tory−installed Schrader valve. A service port cap protects
the Schrader valve from contamination and serves as the
primary leak seal.
Table 2
Torque Requirements
Part Recommended Torque
Service valve cap 8 ft.− lb. 11 NM
Sheet metal screws 16 in.− lb. 2 NM
Machine screws #10 28 in.− lb. 3 NM
Compressor bolts 90 in.− lb. 10 NM
Gauge port seal cap 8 ft.− lb. 11 NM
IMPORTANT
Service valves are closed to the outdoor unit unit and
open to line set connections. Do not open until refrig-
erant lines have been leak tested and evacuated. All
precautions should be exercised in keeping the sys-
tem free from dirt, moisture and air.
Accessing the Schrader Port:
1 − Remove the service port cap with an adjustable wrench.
2 − Connect the gauge to the service port.
3 − When testing is complete, replace the service port cap.
Tighten finger tight, then tighten an additional 1/6 turn.
Opening Liquid or Vapor Line Service Valve:
1 − Remove the stem cap with an adjustable wrench.
2 − Use a service wrench with a hex head extension to back
the stem out counterclockwise as far as it will go.
NOTE − Use a 3/16" hex head extension for liquid line
sizes or a 5/16" extension for vapor line sizes.
3 − Replace the stem cap. Tighten finger tight, then tighten
an additional 1/6 turn.

Page 13
Closing the Liquid or Vapor Line Service Valve:
1 − Remove the stem cap with an adjustable wrench.
2 − Use a service wrench with a hex head extension to turn
the stem clockwise to seat the valve. Tighten firmly.
NOTE − Use a 3/16" hex head extension for liquid line
sizes or a 5/16" extension for vapor line sizes.
3 − Replace the stem cap. Tighten finger tight, then tighten
an additional 1/6 turn.
Liquid or Vapor Service Valve
(Valve Closed)
Schrader valve open
to line set when valve is
closed (front seated)
service
port
service
port cap
stem cap
insert hex
wrench here
(valve front seated)
to outdoor coil
to indoor coil
Liquid or Vapor Service Valve
(Valve Open)
Schrader
valve
service
port
service port
cap
insert hex
wrench here
to indoor coil
to outdoor coil
stem cap
Figure 14
Leak Testing
After the line set has been connected to the indoor and
outdoor units, check the line set connections and indoor
unit for leaks.
WARNING
Danger of fire. Bleeding the refrigerant
charge from only the high side may
result in the low side shell and suc-
tion tubing being pressurized. App-
plication of a brazing torch while pres-
surized may result in ignition of the
refrigerant and oil mixture − check the
high and low pressures before unbra-
zing.
WARNING
Refrigerant can be harmful if it is inhaled. Refrigerant
must be used and recovered responsibly.
Failure to follow this warning may result in person-
al injury or death.
WARNING
Danger of explosion: Can cause
equipment damage, injury or death.
Never use oxygen to pressurize a re-
frigeration or air conditioning system.
Oxygen will explode on contact with
oil and could cause personal injury.
WARNING
Danger of explosion: Can cause equipment damage,
injury or death. 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).
Using an Electronic Leak Detector or Halide
1 − Connect a cylinder of R22 to the center port of the man-
ifold gauge set.
2 − With both manifold valves closed, open the valve on
the R22 cylinder (vapor only).

Page 14
3 − Open the high pressure side of the manifold to allow
the R22 into the line set and indoor unit. Weigh in a
trace amount of R22. [A trace amount is a maximum of
2 ounces (57 g) or 3 pounds (31 kPa) pressure.] Close
the valve on the R22 cylinder and the valve on the high
pressure side of the manifold gauge set. Disconnect
the R22 cylinder.
4 − Connect a cylinder of nitrogen with a pressure regulat-
ing valve to the center port of the manifold gauge set.
5 − Connect the manifold gauge set high pressure hose to
the vapor valve service port. (Normally, the high pres-
sure hose is connected to the liquid line port; however,
connecting it to the vapor port better protects the man-
ifold gauge set from high pressure damage.)
6 − Adjust the nitrogen pressure to 150 psig (1034 kPa).
Open the valve on the high side of the manifold gauge
set which will pressurize line set and indoor unit.
7 − After a few minutes, open a refrigerant port to ensure
the refrigerant you added is adequate to be detected.
(Amounts of refrigerant will vary with line lengths.)
Check all joints for leaks. Purge nitrogen and R22 mix-
ture. Correct any leaks and recheck.
Evacuation
Evacuating the system of noncondensables is critical for
proper operation of the unit. Noncondensables are defined
as any gas that will not condense under temperatures and
pressures present during operation of an air conditioning
system. Noncondensables and water vapor combine with
refrigerant to produce substances that corrode copper pip-
ing and compressor parts.
IMPORTANT
Use a thermocouple or thermistor electronic vacuum
gauge that is calibrated in microns. Use an instrument
that reads from 50 microns to at least 10,000 microns.
1 − Connect the manifold gauge set to the service valve
ports as follows:
 low pressure gauge to vapor line service valve
 high pressure gauge to liquid line service valve
2 −Connect micron gauge.
3 − Connect the vacuum pump (with vacuum gauge) to
the center port of the manifold gauge set.
4 − Open both manifold valves and start the vacuum
pump.
5 − Evacuate the line set and indoor unit to an absolute
pressure of 23,000 microns (29.01 inches of mercu-
ry). During the early stages of evacuation, it is desir-
able to close the manifold gauge valve at least once to
determine if there is a rapid rise in absolute pressure.
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 pres-
sure in a vacuum is equal to atmospheric pressure mi-
nus vacuum pressure.
6 − When the absolute pressure reaches 23,000 microns
(29.01 inches of mercury), close the manifold gauge
valves, turn off the vacuum pump and disconnect the
manifold gauge center port hose from vacuum pump.
Attach the manifold center port hose to a nitrogen cyl-
inder with pressure regulator set to 150 psig (1034
kPa) and purge the hose. Open the manifold gauge
valves to break the vacuum in the line set and indoor
unit. Close the manifold gauge valves.
CAUTION
Danger of Equipment Damage.
Avoid deep vacuum operation. Do not use compres-
sors to evacuate a system.
Extremely low vacuums can cause internal arcing
and compressor failure.
Damage caused by deep vacuum operation will void
warranty.
7 − Shut off the nitrogen cylinder and remove the manifold
gauge hose from the cylinder. Open the manifold
gauge valves to release the nitrogen from the line set
and indoor unit.
8 − Reconnect the manifold gauge to the vacuum pump,
turn the pump on, and continue to evacuate the line set
and indoor unit until the absolute pressure does not
rise above 500 microns (29.9 inches of mercury) with-
in a 20−minute period after shutting off the vacuum
pump and closing the manifold gauge valves.
9 − When the absolute pressure requirement above has
been met, disconnect the manifold hose from the vacu-
um pump and connect it to an upright cylinder of R22
refrigerant. Open the manifold gauge valves to break
the vacuum from 1 to 2 psig positive pressure in the line
set and indoor unit. Close manifold gauge valves and
shut off the R22 cylinder and remove the manifold
gauge set.
Start−Up
IMPORTANT
If unit is equipped with crankcase heater, it should be
energized 24 hours before unit start−up to prevent
compressor damage as a result of slugging.
1 − Rotate fan to check for frozen bearings or binding.
2 − Inspect all factory− and field-installed wiring for loose
connections.

Page 15
3 − After evacuation is complete, open the liquid line and
vapor line service valves (counterclockwise) to release
refrigerant charge (contained in outdoor unit) into the
system.
4 − Replace stem caps and secure finger tight, then tight-
en an additional (1/6) one-sixth of a turn.
5 − Check voltage supply at the disconnect switch. The
voltage must be within the range listed on the unit
nameplate. If not, do not start the equipment until the
power company has been consulted and the voltage
condition has been corrected.
6 − Set the thermostat for a cooling demand, turn on power
to indoor blower unit and close the outdoor unit discon-
nect to start the unit.
7 − Recheck voltage while the unit is running. Power must
be within range shown on the nameplate.
Charging
Units are factory charged with the amount of R22 refrigerant
indicated on the unit’s rating plate. This charge is based on a
matching indoor coil and outdoor coil with a 15 foot (4.6 m)
line set. For varying lengths of line set, see table 3 for adjust-
ing the refrigerant charge.
Table 3
Liquid Line Set
Diameter
Oz. per 5 ft. (grams per 1.5 m) adjust
from 15 ft. (4.6 m) line set*
3/8 in. (10 mm) 3 oz. per 5 ft (85 g per 1.5 m)
*If line length is greater than 15 feet (4.6 m), add this amount. If
line length is less than 15 feet (4.6 m), subtract this amount.
The outdoor unit should be charged during warm weather.
However, applications arise in which charging must occur
in the colder months. The method of charging is deter-
mined by the unit’s refrigerant metering device and the
outdoor ambient temperature.
Measure the liquid line temperature and the outdoor ambi-
ent temperature as outlined below:
1 − Close manifold gauge set valves. Connect the man-
ifold gauge set to the service valves.
 low pressure gauge to vapor valve service port
 high pressure gauge to liquid valve service port
Connect the center manifold hose to an upright cylin-
der of R22.
2 − Set the room thermostat to call for heat. This will create
the necessary load for properly charging the system in
the cooling cycle.
3 − Use a digital thermometer to record the outdoor ambi-
ent temperature.
4 − When the heating demand has been satisfied, switch
the thermostat to cooling mode with a set point of 68F
(20C). When pressures have stabilized, use a digital
thermometer to record the liquid line temperature.
5 − The outdoor temperature will determine which charg-
ing method to use. Proceed with the appropriate charg-
ing procedure.
Weighing in the Charge Fixed Orifice or
TXV Systems – Outdoor Temp. < 65F (18C)
If the system is void of refrigerant, or if the outdoor ambient
temperature is cool, the refrigerant charge should be
weighed into the unit. Do this after any leaks have been re-
paired.
1 − Recover the refrigerant from the unit.
2 − Conduct a leak check, then evacuate as previously
outlined.
3 − Weigh in the unit nameplate charge.
If weighing facilities are not available or if you are charging
the unit during warm weather, follow one of the other proce-
dures outlined below.
Charging Using Normal Operating Pressures
and the Approach Method
TXV Systems – Outdoor Temp. > 65F (18C)
The following procedure is intended as a general guide and
is for use on expansion valve systems only. For best results,
indoor temperature should be 70°F (21°C) to 80°F (26°C).
Monitor system pressures while charging.
1 − Record outdoor ambient temperature using a digital
thermometer.
2 − Attach high pressure gauge set and operate unit for
several minutes to allow system pressures to stabilize.
3 − Compare stabilized pressures with those provided in
table 5, Normal Operating Pressures." Minor varia-
tions in these pressures may be expected due to differ-
ences in installations. Significant differences could
mean that the system is not properly charged or that a
problem exists with some component in the system.
Pressures higher than those listed indicate that the
system is overcharged. Pressures lower than those
listed indicate that the system is undercharged. Verify
adjusted charge using the approach method.
Approach Method
4 − Use the same digital thermometer you used to check
the outdoor ambient temperature to check the liquid
line temperature.
5 − The difference between the ambient and liquid temper-
atures should match values given in table 4. If the val-
ues don’t agree with the those in table 4, add refriger-
ant to lower the approach temperature, or recover re-
frigerant from the system to increase the approach
temperature.
Table 4
Approach Temperature
Approach Temperature
Liquid Line _F − Outdoor Ambient _F
HP21−36 HP21−48 HP21−60
9 + 2 7 + 2 10 + 2
NOTE − For best results, use the same thermometer to check both
outdoor ambient and liquid temperatures.

Page 16
Table 5
Normal Operating Pressures
Mode Out. Coil
Enterin
g
−36 −48 −60
Entering
Air Temp.
5F (5C) Liq. Suc. Liq. Suc. Liq. Suc.
75°(24°)175 74 177 80 182 76
Cooling
TXV
85 °(29°)208 76 190 84 213 79
g
TXV
Onl
y
95°(35°)245 78 228 86 242 80
Only
105°( 41°)277 80 266 88 276 82
20°(−7°)180 33 160 32 175 31
Heatin
g
30°(−1°)191 40 171 40 185 38
Heating
All Units 40°(4°)206 49 184 50 206 47
50°(10°)225 59 204 62 227 57
IMPORTANT
Use table 5 to perform maintenance checks. Table 5
is not a procedure for charging the system. Minor
variations in these pressures may be due to differ-
ences in installations. Significant deviations could
mean that the system is not properly charged or that
a problem exists with some component in the system.
Two−Speed Control (TSC6)
Electrostatic Discharge (ESD)
Precautions and Procedures
CAUTION
Electrostatic discharge can affect electronic com-
ponents. Take precautions during furnace installa-
tion and service to protect the furnace’s electronic
controls. Precautions will help to avoid control ex-
posure to electrostatic discharge by putting the fur-
nace, the control and the technician at the same
electrostatic potential. Neutralize electrostatic
charge by touching hand and all tools on an un-
painted unit surface, such as the gas valve or blower
deck, before performing any service procedure.
The two−speed control changes the speed of the compres-
sor based on demands from the indoor thermostat. See fig-
ure 15 for TSC6 control component identification. The con-
trol features diagnostic lights and the capability of storing
diagnostic codes.
You may choose various modes of operation by changing
the jumper selections. A manual override button is located
on the control to bypass some time delays and to display
memorized problem codes. The control allows for two dif-
ferent compressor safety options to be used with an op-
tional safety device such as a low ambient kit. The control
is also equipped with a service light relay. Diagnostic
lights indicate in which speed the unit is operating, if the
control is functioning properly, and if any failures or fault
conditions exist.
Safety Lockout Conditions
If the motor windings overheat, the TSC6 will stop the
compressor. The compressor stops operating for either a
minimum of five minutes or until the motor windings cool to
a temperature within a specified range.
The control will lock out the compressor operation for
five minutes when a safety device (high pressure
switch) terminates operation.
Compressor operation will lock out if overheating or
compressor safety devices interrupt the compressor
operation three times during one thermostat demand.
Compressor operation is locked out until the thermo-
stat demand is removed or power supply to control is
removed.
The control has an adjustment potentiometer (POT)
which is used for setting the low speed lockout tempera-
ture. The adjustment range is 38°F to 55°F +/− 2°F
(3.3°C to 12.78°C, +/− 1.1°C). This lockout will occur in
both heating and cooling modes.
Time Delays
Speed Change Delay − provides a one−minute delay be-
tween speed changes which cannot be bypassed.
Short Cycle Protection Delay − prevents compressor
from short cycling with a five minute timed−off delay.
This delay may be bypassed by pushing the override
button on the control.
Thermostat Bounce Delay − ignores any momentary
openings or closing of the thermostat inputs, for three
seconds, which avoids increased cycling due to ther-
mostat switch bounces.

Page 17
Fi
gu
r
e
1
5
TSC6 Two-speed Control Components
Diagnostic LEDs
D8, D4, D2, D1
(see table 6 for diagnostic codes)
Y1 LED
Y2 LED
Main Control Plug
High Speed
LED
Low Speed
LED
Service Relay
Connectors
Heartbeat
LED
Mode Selection
Jumpers
Option 1 Enable
Jumper OPtion 2 Enable
Jumper
Option 2
Connector
Compressor Sensor
Connectors
Manual Override
Button
Option 1
Connector
Outdoor Temp.
Sensor Connector
Low Speed Lockout
Temperature Adjust
Manual Override Button
The two−speed control is equipped with a manual override
button that bypasses the five−minute timed−off delay for
servicing unit. It does not bypass the one−minute delay be-
tween the speed changes.
The override button is also used to initiate the Test mode,
step back through the stored diagnostic codes, and erase
the code memory.
Service Light Relay
The control is equipped with a 24VAC / 1 amp service light
relay. This relay can be used with thermostats equipped
with a service light to indicate a lockout condition or other
problems. Connecting the thermostat terminal L to this
relay will display a lockout at the thermostat.
Mode Jumper Selections
The TSC6 has six jumper settings to
select the operating modes, recall a
diagnostic problem code, or to run a
diagnostic test.
The Normal, Latch1, 2, and 3 jumper
settings are operational mode selec-
tions. Latch 1, 2, and 3 jumper settings
allow for various customized two−speed operations different
than the Normal mode. These selections are helpful in high
humidity areas.
Normal − Select this jumper setting for normal two−speed
operation. Upon a Y1 demand, the compressor oper-
ates on low speed and upon a Y2 demand, the com-
pressor operates on high speed whether or not a de-
mand for Y1 is present. Normal is the default mode.
Latch 1 − After a high speed demand, the control allows the
compressor to latch into high speed until the low speed
demand is met.
Latch 2 − This mode limits the time the compressor can run
in low speed to 15 minutes. After operating at low
speed for 15 minutes, the control switches the com-
pressor to high speed until low speed demand has
been met.
Latch 3 − This mode limits the time the compressor can run
in low speed to 30 minutes. After operating in low
speed for 30 minutes, the control switches the com-
pressor to high speed until low speed demand is met.
Recall − This jumper setting is used in with the override but-
ton to recall the stored diagnostic codes. By pressing
the override button, the stored codes are displayed as
shown in the Diagnostic LED section. The control will
continue to operate in the mode in which it was pre-
viously operating before the jumper was moved to Re-
call. However, if a reset (loss of power) has occurred
while the jumper is in the recall position, the control will
default to Normal operation. If problems are detected
during Recall, the control will take action but not store
or display the codes.
Test − This jumper setting is used in with the override button
to test the two−speed control. See the Test Mode sec-
tion below.
IMPORTANT
If the jumper falls off, is left off, or is left in the Recall
or Test position, the control will continue to operate
in the mode that it previously operated in until the
control is reset (loss of power). After a reset or loss
of power, the control will default to the Normal mode.
TEST
RECALL
LATCH3
LATCH2
LATCH1
NORMAL
Fi
g
ure 16
Mode Jumper
Selections

Page 18
Options 1 and 2 Jumper Selections
These two jumper settings are used with optional safety
devices (with a normally closed switch) such as a low
ambient control. Unless an optional kit is being used
with the HP21, the jumper setting for options 1 and 2
must be on NO. Placing the jumper on YES without an op-
tional kit will cause a lockout condition.
Option 1 − This jumper assists an optional safety kit and will
lock out the compressor after the third occurrence of a
problem (open contacts) with the optional safety de-
vice. To reset the control, remove the power or the
cycle thermostat demand.
Option 2 − This jumper assists an optional safety device
and will only display and store the code for kit related
problems (open contacts). The control will not lockout
the compressor through Option 2.
Diagnostic LEDs
Diagnostic troubleshooting lights (LEDs) and operational
lights are located on the two−speed control.
Y1 and Y2 LEDs are connected directly to the inputs from
the thermostat. These two lights indicate the room
thermostat demands.
HI and LO LEDs are connected directly across the contac-
tor coils and indicate if the high or low speed contactors
are energized.
HB LED (also called HeartBeat) is connected to the brains
of the two−speed control to indicate that the control itself
is functioning properly. The light also indicates if the
control is in a delay (such as the 1 or 5 minute delay).
During normal operation, the HB light will blink four
times a second. If the control is in delay, the light will
blink once every two seconds. If the HB light is continu-
ously on or off (when power is on), the control is not
functioning properly and should be replaced.
1, 2, 4, and 8 LEDs are used to display diagnostic codes in-
dicating a lockout, problem, or condition. Each problem
code is numbered. To convert the row of lights to code
numbers, add the display numbers together for all the
lights that are on. For example, if lights 2 and 8 are on,
the display code is 10: (2 + 8 = 10). If lights 1, 2, and 4
are on, the display code is 7: (1 + 2 + 4 = 7). See table 6
for each problem code and the corresponding number.
Test Mode Procedure
The TSC6 two−speed control test mode allows you to test
the control as well as the HP21 contactors and compres-
sor.
To initiate the test mode, position the mode jumper on the
TEST jumper selection and press the manual override but-
ton. The override button starts the test sequence; if you do
not press the override button, the control will remain in the
last selected mode. Once the TEST procedure starts, Code
14 will be displayed until the jumper is moved. The control
will operate the compressor in low speed for ten seconds,
turn off for ten seconds, then operate in high speed for ten
seconds. If the test detects a problem condition, the code is
displayed. See table 6.
NOTE − The control will only go into TEST mode if there is
no thermostat demand, and five minutes have elapsed
since the last test. The TEST mode will only be allowed to
run once every five minutes so as not to damage the com-
pressor.
If the compressor is operating when the jumper is in the
TEST mode position, the control will not start the test until
the demand is met. If there is no demand, pressing the but-
ton to override the five minute delay will start the test opera-
tion immediately.
If the jumper is moved after the test sequence has started,
the control will continue with the test until completion. If the
jumper is left in the TEST position, the control will continue to
operate (at the next demand) in the previous mode until a
reset occurs. After a reset, the control defaults to NORMAL
mode operation.
Diagnostic Code Display
A problem code is normally displayed only for the duration of
the error. However, there is one exception. During a lockout,
the code for the problem that is causing the lockout flashes
once a second even if the problem condition no longer exists.
If other problems occur during a lockout condition, the codes
for those problems will be saved in memory, but not dis-
played. The stored problem codes are displayed by recalling
them from memory.
Not all codes cause lockouts or indicate problems. The
diagnostic lights tell the installer or service technician the
status of the entire system, not just the two−speed con-
trol. Some codes do indicate malfunctions or problems
with either the control or the HP21. Others inform the
technician of the unit’s status. All codes (with the excep-
tion of codes 2, 13 and 15) are stored in memory and may
be recalled.
Code 1 − Power Loss for Two Electrical Cycles
This code indicates that the unit’s power skipped two elec-
trical cycles (33−40 milliseconds), and it may suggest the
power to the unit is dirty" or is of low quality. Code 1 is
stored.
Code 2 − Input Indication
This code indicates that a change has been made and that
the control acknowledges the change. It does not indicate a
problem condition. A change could consist of moving jump-
er settings, pressing the override button to override a delay,
or adding an optional safety device to Option 1 or 2. Code 2
is not stored.
Code 3 − Unsteady Thermostat Input
Code 3 indicates intermittent inputs from the room thermo-
stat. Most likely, there is a loose connection at the thermo-
stat when this condition appears. Code 3 is stored.

Page 19
Table 6
TSC6 Diagnostics Codes
Code #
Condition
Display Lights
Code # Condition 8 4 2 1
1Power loss for two cycles OFF OFF OFF ON
2Input Indication OFF OFF ON OFF
3Unsteady Input OFF OFF ON ON
4Pressure Switch Open
<2 minutes
OFF ON OFF OFF
5Pressure Switch Open
> 2 minutes
OFF ON OFF ON
6Hot Compressor < 5 min.
(or open sensor)
OFF ON ON OFF
7Hot Compressor > 5 min.
(or open sensor)
OFF ON ON ON
8Option 1 < 5 minutes ON OFF OFF OFF
9Option 1 > 5 minutes ON OFF OFF ON
10 Option 2 Open ON OFF ON OFF
11 Compressor Temperature
Sensor Problem
ON OFF ON ON
12 Outdoor Temperature
Sensor Problem
ON ON OFF OFF
13 Not Used ON ON OFF ON
14 Test Mode ON ON ON OFF
15 No Jumper in Place
Indication
ON ON ON ON
Code 4 − Pressure Switch Opens < Two Minutes
If the low or high pressure switch opens after the compres-
sor has run for less than two minutes, Code 4 is displayed.
This may indicate blockage or fan failure. Code 4 is stored.
If the unit still operates after Code 4 is displayed, the low
pressure switch stops operation (low pressure is auto−re-
set). Check for low system charge.
Code 5 − Pressure Switch Opens > Two Minutes
If the low or high pressure switch opens after the compres-
sor has run for more than two minutes, Code 5 is displayed.
This may indicate an improper charge or coil obstruction.
Code 5 is stored. If the unit still operates after code 5 is dis-
played, the low pressure switch stops operation (low pres-
sure is auto−reset). Check for low system charge.
Code 6 − Hot Compressor < Five Minutes
Code 6 indicates the compressor temperature has exceeded
its limit after running less than five minutes. Code 6 is stored.
Code 7 − Hot Compressor > Five Minutes
Code 7 indicates the compressor temperature exceeded
its limit after running more than five minutes. Code 7 is
stored.
Code 8 − Option 1 < Five Minutes
Code 8 occurs if the Option 1 safety device switch opens
after the compressor runs less than five minutes. Code 8 is
stored.
Code 9 − Option 1 > Five Minutes
Code 9 occurs if the Option 1 safety device switch opens
after the compressor runs more than five minutes. Code 9
is stored.
Code 10 − Option 2
Code 10 is displayed if the Option 2 safety device switch
opens. Code 10 is stored.
Code 11 − Compressor Temperature Sensor Shorted
This code indicates that the compressor temperature sen-
sor wires have shorted together. Code 11 is stored.
Code 12 − Outdoor Temperature Sensor Shorted
This code indicates a problem with the operation of the out-
door temperature sensor. Code 12 is stored.
Code 13 − Not Used
This code may be used in future models of the TSC6 two−
speed control but at this time has no function and therefore
is not stored.
Code 14 − Test Mode
Code 14 does not indicate a problem. The control is in
TEST mode when this code is displayed. See Mode Jump-
er Selections section. Code 14 is stored.
Code 15 − No Jumper in Place
Code 15 is displayed when the mode jumper is not in place.
Make sure jumper is placed securely across the selected
set of pins for the appropriate mode of operation. Code 15
is not stored.
Recalling Stored Diagnostic Codes
To recall stored diagnostic codes, place mode jumper on
the Recall setting.
The codes are recalled in opposite order of occurrence (the
last condition to occur is the first condition displayed).
Press the override button to display each diagnostic code.
Each time the you press the override button, the next code
stored in memory will be displayed. The control will store
the most recent 63 diagnostic codes even if the power is re-
moved. When the last code has been displayed, that code
will stay on until the codes are erased.
To erase the stored codes from memory, press the override
button until the code lights go off (approximately 5 sec-
onds). Erase stored codes after every service call.
System Operation
The outdoor unit and indoor blower run through a cycle when
the thermostat sends a demand. When the thermostat blower
switch is moved to the ON position, the indoor blower oper-
ates continuously.

Page 20
High Pressure Switch
HP21 units are equipped with a high pressure switch that is
located in the discharge line of the compressor. The switch
(SPST, manual reset, which is normally closed) removes
power from the compressor when the discharge pressure
rises above the factory setting at 410 + 10 psig.
Low Pressure Switch
HP21 units are also equipped with a low pressure switch
that is located in the vapor line of the compressor. The
switch (SPST, auto−reset, normally closed) removes power
from the compressor when vapor line pressure drops be-
low the factory setting at 25 + 5 psig.
Crankcase Temperature Limit Switch
HP21 units are equipped with a crankcase temperature
limit switch which is strapped to the outside bottom of the
compressor shell. This limit switch prevents compressor
operation at exceedingly high oil temperature by opening
the control circuit at 190°F (87.8°C). It automatically resets
at 110°F (43.3°C).
Crankcase Heater
IMPORTANT
Crankcase heater (when provided) should be ener-
gized 24 hours before unit start−up. This heater must
always be energized before start−up to prevent com-
pressor damage as a result of slugging.
Filter Drier
The HP21 drier is equipped with an internal check valve for
correct refrigerant flow (Refer to figure 13). If replacement
is necessary, order another of like design and capacity. A
liquid line strainer gives additional compressor protection.
Thermostat Operation
The electromechanical room thermostat is not included
with the unit and must be purchased separately. The ther-
mostat incorporates isolating contacts and an emergency
heat function (which includes an orange indicating light).
The thermostat displays additional indicator lights and
uses an ambient compensating thermistor. Each feature is
explained below.
1 − Emergency Heat (Orange Light) − An emergency
heat function is designed into the thermostat. This fea-
ture is applicable only to those systems with auxiliary
electric heat staged by outdoor thermostats. When the
thermostat is placed in the emergency heat position,
the outdoor unit control circuit is isolated from power
and field−provided relays bypass the outdoor thermo-
stats. An orange indicating light simultaneously comes
on to remind the homeowner that the unit is operating
in the emergency heat mode.
Emergency heat is usually used during a outdoor unit
shutdown. 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.
2 − Service Light (Red) −The service light is wired in series
with the second−stage heat bulb of the room thermostat
and a thermal sensor that is strapped to the compressor
discharge line. The sensor monitors discharge temper-
ature and closes on a temperature fall which indicates
the compressor is not operating properly and that ser-
vice is required. A red light represents an outdoor unit
malfunction during the heating mode. It warns the
homeowner that the electric elements are providing all
the heat.
If the red light comes on, place the room thermostat
into emergency heat to bypass any outdoor thermo-
stat(s) making all the auxiliary heat available. Under
these conditions, the orange light will be energized
continuously and the red light will cycle with the indoor
unit.
3 − When the system is operating on low speed the green
light will come on.
4 − When the system is operating on high speed the amber
light comes on.
5 − The ambient compensating thermistor (located in the
outdoor unit) cuts down thermostat droop to improve the
operating characteristics of the outdoor unit system.
Defrost System
Components
HP21 units are equipped with a demand defrost system
which initiates a defrost cycle based on temperature differ-
ential and compressor run time. The control board includes
two permanently attached sensors which monitor coil and
outdoor ambient temperatures. The coil temperature sen-
sor is equipped with a spring clip which allows proper posi-
tioning on the outdoor coil return bend. The ambient tem-
perature sensor is installed in a sampling tube at the base
of the unit. These sensors must not be detached from the
control board and must be replaced as part of the control
board. Do not attempt to cut or splice the temperature sen-
sor wires.