Armstrong Air RP16AC Series User manual
507635-05 Page 1 of 22Issue 2245
INSTALLATION AND MAINTENANCE
INSTRUCTIONS
*RP16AC AND *RP16HP SERIES UNITS
RESIDENTIAL PACKAGED UNITS
Air Conditioners and Heat Pumps
507635-05
11/2022
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
Save these instructions for future reference
Table of Contents
Unit Dimensions ..........................................................2
Roof Curb Dimensions ................................................4
Adjustable Roof Curb Dimensions...............................6
Installation ...................................................................9
Electrical Wiring.........................................................11
Duct System ..............................................................12
Condensate Drain......................................................12
Sequence of Operation..............................................14
Defrost System..........................................................15
System Performance.................................................18
Maintenance..............................................................18
Wiring Diagrams........................................................21
The installation of this appliance must conform to the requirements of the National Fire Protection Association; the National
Electrical Code, ANSI/NFPA No. 70 (latest edition) in the United States; the Canadian Electrical Code Part 1, CSA 22.1
(latest edition) in Canada; and any state or provincial laws or local ordinances. Local authorities having jurisdiction should
be consulted before installation is made. Such applicable regulations or requirements take precedence over the general
instructions in this manual.
CAUTION
See Unit Nameplate for Manufacturer
(P) 507635-05
*P507635-05*
Installation and servicing of air conditioning equipment
can be hazardous due to internal refrigerant pressure
and live electrical components. Only trained and
qualied service personnel should install or service
this equipment. Installation and service performed by
unqualied persons can result in property damage,
personal injury, or death.
WARNING
For your safety, do not store or use gasoline or other
ammable vapors and liquids in the vicinity of this or any
other appliance. Such actions could result in property
damage, personal injury, or death.
WARNING
Page 2 of 22 507635-05Issue 2245
12.12
3.87
3.62
4.06
29.59
34.19
POWER ENTRY
1-1/8 DIA. KNOCKOUT
LOW VOLTAGE ENTRY
7/8 DIA. KNOCKOUT
ELECTRIC HEAT
POWER ENTRY
5.863.07
6.20
17.07
13.44
13.44
14.32
6.20
40.89 21.63
13.21
TYPICAL DRAIN
LOCATION
CONDENSATE
DRAIN 3/4 NPT
SIDE VIEWS
11.49
2.33
47.66
1.98
16.77
2.48
14.02
47.66
POWER ENTRY
POWER ENTRY
6.94
2.33
11.49 16.07
18.52
3.25
4.56
20.31
21.06
23.19
RETURN
AIR
SUPPLY
AIR
TOP VIEW
Unit Dimensions - Small Base Air Conditioners & Heat Pumps
507635-05 Page 3 of 22Issue 2245
3.87
3.62
4.06
38.19
12.14
33.59
POWER ENTRY
1-1/8 DIA. KNOCKOUT
LOW VOLTAGE ENTRY
7/8 DIA. KNOCKOUT
ELECTRIC HEAT
POWER ENTRY
14.32
4.20
3.76
6.20
17.07
18.19 18.19
6.20
44.89 21.63
13.21
TYPICAL DRAIN
LOCATION
CONDENSATE
DRAIN 3/4 NPT
SIDE VIEWS
TOP VIEW
POWER ENTRY
POWER ENTRY
RETURN
AIR
2.11
19.49
2.39 2.33
11.49 16.07
18.52
6.94
3.25
10.06
19.49
SUPPLY
AIR
25.81
26.56
28.68
11.49
2.33
47.66
56.13
Unit Dimensions - Large Base Air Conditioners & Heat Pumps
Page 4 of 22 507635-05Issue 2245
NOTE - Roof deck may be omitted within confines of curb.
Insulated
Panels
Opening for Power Entry
Through Unit Base
5-1/2 x 5-5/8 in.
(140 x 31 mm)
Opening for Power Entry
Through Unit Base
3 x 13 in.
(76 x 330 mm)
44-3/8
(1127)
44-3/8
(1127)
16-7/8
(429)
13-7/8
(352)
2-1/8
(54)
11-1/2
(287)
SUPPLY
OPENING
RETURN
OPENING
8 (203)
14 (356)
18 (457)
24 (610)
3/4 (19)
1 (25)
5-1/2
(140)
5-3/4
(146)
11-1/2
(287)
17-1/4
(438)
1-3/8
(35)
3-3/4
(95)
13
(330)
3
(76)
Roof Curb Dimensions - Small Base Air Conditioners & Heat Pumps
507635-05 Page 5 of 22Issue 2245
NOTE - Roof deck may be omitted within confines of curb.
Insulated
Panels
Opening for Power Entr
y
Through Unit Base
5-1/2 x 5-5/8 in.
(140 x 31 mm)
Opening for Power Entry
Through Unit Base
3 x 13 in.
(76 x 330 mm)
52-7/8
(1343)
44-3/8
(1127)
19-1/2
(380)
11-1/2
(287)
19-1/2
(380)
2-1/8
(54)
11-1/2
(287)
SUPPLY
OPENING
RETURN
OPENING
8 (203)
14 (356)
18 (457)
24 (610)
3-3/4
(95)
22-7/8
(581)
7 (178)
3/4 (19)
1 (25)
Roof Curb Dimensions - Large Base Air Conditioners & Heat Pumps
Page 6 of 22 507635-05Issue 2245
Top Edge
Wood Nailer Strip
Bottom Flange
Typical Slot
Typical Locking Ta b
See Cliplock 1000 installation instructions for complete
assembly and installation procedures and requirements.
NOTE:
CLIPLOCK CORNER DETAIL
CURB PROFILE
1
1/2
1-3/4
1
11-5/8
2-1/8
14
1
3-1/2
13-1/2
44-3/8
Bottom Curb
Assembly
Opening for Power
Entry thru base
11-5/8
5-1/2
5-3/4
3-5/8 1-3/8
17-1/4
13-7/8
16-7/8
44-3/8
Insulated Panels
Opening for Power
Line Entry thru base
NOTE - Roof deck may be omitted within confines of curb.
Adjustable Roof Curb Dimensions - Small Base Air Conditioners & Heat Pumps
(Knock-Down Style)
507635-05 Page 7 of 22Issue 2245
Top Edge
Wood Nailer Strip
Bottom Flange
Typical Slot
Typical Locking Ta b
See Cliplock 1000 installation instructions for complete
assembly and installation procedures and requirements.
NOTE:
CLIPLOCK CORNER DETAIL
CURB PROFILE
1
1/2
1-3/4 1
19-5/8
11-5/8
2-1/8
19-3/8
11-5/8
14
23-1/8
1
5-1/2
5-3/4
3-1/2
3-1/2
13-1/2
6-7/8
52-7/8
44-3/8
Insulated Panels
Opening for Power
Line Entry thru base
Bottom Cur
b
Assembly
Opening for Power
Entry thru base
NOTE - Roof deck may be omitted within confines of curb.
Adjustable Roof Curb Dimensions - Large Base Air Conditioners & Heat Pumps
(Knock-Down Style)
Page 8 of 22 507635-05Issue 2245
Adjustable Roof Curb Dimensions - Air Conditioners & Heat Pumps
(Welded Style)
A
BC
3/4 (76)
6
(152)
1
(25)
11 -1/2
(292)
42-7/8
(1089)
2-1/ 8
(54)
Built-In Rain
Diverter
(Not Shown)
Front Flange
8 (203)
NOTE:
Minimum
Height
4 (102)
Built-In Drip Edge
Unit Base Rail
Unit Base Rail
Clips (4)
Sides and
Back Flange
6 (152)
Unit Base Rail
Clips (4)
Supply
Air
Opening
Return
Air
Opening
Usage A B C
in. mm in. mm in. mm
24,30,36 42-7/8 1089 13-7/8 352 16-7/8 429
42,48,60 51-3/8 1305 19-1/2 495 19-1/2 495
507635-05 Page 9 of 22Issue 2245
Improper installation, adjustment, alteration, service,
or maintenance can cause injury or property damage.
Refer to this manual. For assistance or additional
information, consult a qualied installer or service
agency.
WARNING
Installation
These instructions explain the recommended method
of installation of the packaged heat pump and/or air
conditioner units and associated electrical wiring.
This unit is designed and approved for use as a self-
contained air-to-air outdoor heat pump and air conditioner
system.
The units are factory-equipped with a transformer and
blower control for applications without auxiliary heat.
Electric heat accessory kits (PHK-) can be ordered for eld
installation of additional heat where required.
These instructions, and any instructions packaged with
mating components and/or accessories, should be carefully
read prior to beginning installation. Note particularly any
CAUTIONS or WARNINGS in these instructions and all
labels on the units.
These instructions are intended as a general guide only,
for use by qualied personnel and do not supersede any
national or local codes in any way. Compliance with all local,
state, provincial, or national codes pertaining to this type of
equipment should be determined prior to installation.
Inspection of Shipment
Upon receipt of equipment, carefully inspect it for possible
shipping damage. If damage is found, it should be noted on
the carrier’s freight bill. Take special care to examine the
unit inside the carton if the carton is damaged. If damaged,
le a claim with the transportation company.
If any damages are discovered and reported to the carrier,
DO NOT INSTALL THE UNIT, as claim may be denied.
Check the unit rating plate to conrm specications
are as ordered.
Limitations
The unit should be installed in accordance with all national
and local safety codes.
Limitations of the unit and appropriate accessories must
also be observed.
The unit must not be installed with any ductwork in the
outdoor air stream. The outdoor fan is not designed to
operate against any additional static pressure.
Location
The unit is designed to be located outdoors with sucient
clearance for free entrance to the air inlet and discharge
air openings. The location must also allow for adequate
service access.
The unit must be installed on a solid foundation that will
not settle or shift. Adequate structural support must be
provided. Install the unit in level position. Isolate the base
from the building structure to avoid possible transmission
of sound or vibration into the conditioned space.
The heat pump unit foundation should be raised to a
minimum of 3” above nish grade. In areas which have
prolonged periods of temperature below freezing and
snowfall, the heat pump unit should be elevated above the
average snow line. Extra precaution should be taken to
allow free drainage of condensate from defrost cycles to
prevent ice accumulation. The unit should not be located
near walkways, to prevent possible icing of surface from
defrost condensate.
Avoid placing the unit near quiet areas, such as
sleeping quarters or study rooms. Normal operating
sound levels may be objectionable if the unit is placed near
certain rooms.
For improved start-up performance, the condenser coil
should be washed with suitable detergent to remove
any residue from manufacturing processes.
Use of Unit During Construction
Use of this unit as a construction heater or air conditioner is
not recommended during any phase of construction. Very
low return air temperatures, harmful vapors and operation
of the unit with clogged or misplaced lters will damage
the unit.
If this unit has been used for heating or cooling of buildings
or structures under construction, the following conditions
must be met or the warranty will be void:
• A room thermostat must control the unit. The use of
xed jumpers that will provide continuous heating or
cooling is not allowed.
• A pre-lter must be installed at the entry to the return
air duct.
• The return air duct must be provided and sealed to
the unit.
• Return air temperature range between 55°F (13°C)
and 80°F (27°C) must be maintained.
• Air lters must be replaced and pre-lters must be
removed upon construction completion.
• The input rate and temperature rise must be set per
the unit rating plate.
• The heat exchanger, components, duct system, air
lters and evaporator coil must be thoroughly cleaned
following nal construction clean-up.
Page 10 of 22 507635-05Issue 2245
Compressor
Units are shipped with compressor mountings factory
adjusted and ready for operation. Do not loosen compressor
mounting bolts.
Roof Curb Installation
If a roof curb is used, follow the manufacturer’s installation
instructions and be sure that all required clearances are
observed (see Clearances section).
Prior to setting the unit on the roof curb, the shipping
bracket located underneath the unit must be removed.
Remove the two screws in the base rail (located on the
front and rear sides of the unit). The four screws and the
bracket can be discarded. See Figure 1.
Rigging Unit
Exercise care when moving the unit. Do not remove any
packaging until the unit is near the place of installation.
1. Connect rigging to the unit base rails using both holes
in each corner.
2. All panels must be in place for rigging.
3. Place eld-provided spreaders in place. Spreaders
must be of adequate strength and length (must exceed
unit dimension by 6 inches).
Units may also be moved or lifted with a forklift. The
lengths of the forks of the forklift must be a minimum
of 42 inches.
• The unit operating conditions (including airow,
cooling operation, ignition, input rate, temperature
rise and venting) must be veried according to these
installation instructions.
Clearances
All units require certain clearances for proper operation
and service. Refer to Table 1 for the minimum clearances
to combustibles required for construction, servicing, and
proper unit operation.
In the U.S., units may be installed on combustible oors
made from wood or class A, B, or C roof covering material.
In Canada, units may be installed on combustible oors.
Units must be installed outdoors.
Do not permit overhanging structures or shrubs to
obstruct condenser air discharge outlet.
Clearance to
Combustibles
Clearance for
Service Access
Front of unit 0 in. 24 in.
Back of unit 0 in. 0 in.
Left side 0 in. 24 in.
Right side 0 in. 24 in.
Base of unit 0 in. 0 in.
Top of unit 0 in. 48 in.
For any future service, installer must provide access to
screws of top and rear panels.
Table 1. Minimum Clearances
Shipping Bracket and Mounting Screws Must be
Removed for Rooftop or Downflow Application
Field-Provided Lifting
Spreaders Recommended
Figure 1.
507635-05 Page 11 of 22Issue 2245
Before lifting a unit, make sure that the weight is
distributed equally on the cables so that it will lift evenly.
CAUTION
Unpacking
Locate the four stacking brackets at each corner of the top
panel. Remove the screws and washers that secure these
brackets. All screws must be re-installed. The washers and
stacking brackets can be discarded. Remove the bag and
remaining packaging material, which can be discarded.
Locate the four plastic fork slot bumpers on the base rails.
Remove the fasteners and bumpers and discard.
As with any mechanical equipment, personal injury can
result from contact with sharp sheet metal edges. Be
careful when you handle this equipment.
CAUTION
Service Access
Access to all serviceable components is provided by four
removable panels: upper access panel (for blower, ID coil,
and optional lter), Aux heat access, control access panel,
and compressor access.
This unit is charged with HFC-410A refrigerant.
Operating pressures for units charged with HFC-410A
are higher than pressures in units charged with HCFC-
22. All service equipment MUST be rated for use with
HFC-410A refrigerant.
WARNING
Electrical Wiring
All eld wiring must be done in accordance with National
Electrical Code recommendations, local codes, and
applicable requirements of UL Standards, or in accordance
with Canadian Electrical Code recommendations, local
codes, or CSA Standards.
Power wiring, disconnect means, and over-current
protection are to be supplied by the installer. Refer to the
unit rating plate for maximum over-current protection and
minimum circuit ampacity, as well as operating voltage.
The power supply must be sized and protected according
to specications supplied.
The unit must be grounded with a separate ground
conductor. See Figure 2 for typical eld wiring connection.
The wiring diagram can be found on the unit inside the
access panel. Low voltage control wiring are terminal strip
or pigtail leads located on the main control box and are
color-coded to match the connection called out on the
wiring schematic.
NOTE: An optional bottom-entry power kit is available for
these units. See the kit instructions for proper installation
details.
Figure 2. Typical Wiring Connections
R
G
W
O
Y2
Y1
C
R
G
W
O
Y2
Y1
C
THERMOSTAT OUTDOOR UNIT
Red
Blue
Yellow
Yellow w/
Blue Stripe
Orange
White
Green
*
!CAUTION
required by the indoor thermostat. Refer to the
thermostat installation instructions.
Do not connectconnections except when
C
*“O” connection used only on heat pump models
SINGLE PHASE
L2 L1 GROUND
SCREW
POWER WIRING
208/230-1-60
(75° MIN. WIRE)
POWER WIRING
24V CONTROL WIRING
(NEC CLASS 2)
W1, W2 can be used to stage electric heat accessory on 10,
15 & 20 kW models. 5 And 7 kW heater accessory function
o W1 only.
When connecting electrical power and control wiring
to the unit, waterproof-type connectors must be used
so that water or moisture cannot be drawn into the unit
during normal operation.
CAUTION
Units are factory wired for a 230-volt power supply.
If power supply is 208 volts, it will be necessary to
change a wire connection on the unit transformer from
240V terminal to 208V terminal as shown on the wiring
diagram.
Page 12 of 22 507635-05Issue 2245
Use only copper conductors.
If any of the original unit wiring is replaced, the same size
and type wire must be used.
If 208 Volt is supplied, transformer connection
must be changed
SINGLE PHASE
POWER SUPPLY
GROUND
LUG
CONTACTOR FIELD-SUPPLIED FUSED
OR CIRCUIT BREAKER
DISCONNECT
Figure 3. 208 / 230 Line Voltage Wiring
Thermostat
The room thermostat should be located on an inside
wall where it will not be subject to drafts, sun exposure,
or heat from electrical xtures or appliances. Follow the
manufacturer’s instructions enclosed with the thermostat
for general installation procedure. Color-coded insulated
wires (#18 AWG) should be used to connect the thermostat
to the unit. A minimum of ve wires are required for proper
installation.
Duct System
The duct system should be designed and sized according
to the methods in the Air Conditioning Contractors of
America (ACCA) manual that is most appropriate to the
installation application.
A closed return duct system shall be used. This shall not
preclude use of economizers or outdoor fresh air intake. It
is recommended that supply and return duct connections
at the unit be made with exible joints.
The supply and return air duct systems should be designed
for the CFM and static requirements of the job. They
should not be sized to match the dimensions of the duct
connections on the unit.
The unit is shipped ready for horizontal ow (side duct
connections) or downow (bottom duct connections). All
units are equipped with a drain pan overow switch that is
installed and wired at the factory. Duct attachment screws
are intended to go into the duct panel anges. Duct to unit
connections must be sealed and weather proofed.
For horizontal duct systems:
1. Remove the duct covers on side of the unit. They can
be discarded.
2. Install the duct system to the unit.
For downow duct systems:
1. Remove the duct covers on side of the unit. Keep the
screws and the covers as they will be re-installed later.
2. Remove the downow duct covers located inside unit.
Remove the four screws securing each cover. Remove
the covers from the unit. They can be discarded.
3. Remove screws located between the supply and
return air openings that attach the blower deck to the
base pan. These screws can interfere with bottom duct
connections or roof curb seals. Discard these screws.
4. Install the duct system to the unit.
5. Re-install the duct covers removed in Step 1.
Filters
Air lters are not supplied with the unit. A eld-provided air
lter must always be installed ahead of the evaporator coil
and must be kept clean or replaced. Dirty lters will reduce
the airow of the unit.
An optional lter rack kit may be purchased separately
for installation inside the unit’s coil compartment. Air lter
sizes are shown in Table 2 for use with lter rack kit.
The lter rack must be installed prior to installation of
the unit in applications where access to the rear panel
is limited.
NOTE:
Unit Model Filter 1 Filter 2
24,36 14 x 20 x 1 20 x 20 x 1
48,60 20 x 20 x 1
Table 2. Unit Air Filter Sizes - inches
A Photocatalytic Oxidation (PCO) air purication system
is available as a eld-installed accessory for this product.
A wiring harness for the installation of this accessory
has been factory installed. If this accessory is going to
be installed, it becomes critical that the system lter be
installed ahead of this unit’s return. Therefore, see the
PCO accessory for lter requirements, plan the installation
of lter ahead of this unit, and do not use the internal
lter rack described above.
Condensate Drain
Drain lines should be hand-tightened only. Do not use
tools to tighten tting into drain.
CAUTION
This package unit is equipped with a 3/4” FPT coupling
for condensate line connection. Plumbing must conform
507635-05 Page 13 of 22Issue 2245
to local codes. Use a sealing compound on male pipe
threads.
Figure 4. Typical Condensate Drain Connection
UNIT
Minimum Pitch
1 in. (25 mm)
per 10' (3 m) of line
MOUNTING
FRAME
OPEN
VENT
Trap must be deep enough to offset maximum
static difference (generally, 3 inches (76mm)
minimum). In addition, the drain lines must be
supported if longer than 10 feet.
Trap must be primed at start-up.
Do not operate unit without a drain trap. The condensate
drain is on the negative pressure side of the blower;
therefore, air being pulled through the condensate line will
prevent positive drainage without a proper trap.
The condensate drain line must be properly trapped,
routed to a suitable drain and primed prior to unit
commissioning.
NOTE: Install drain lines and trap so they do not block
service access to the unit.
See Figure 4 for proper drain arrangement. The drain line
must pitch to an open drain or pump to prevent clogging
of the line. Seal around the drain connection with suitable
material to prevent air leakage into the return air system.
To prime trap, pour several quarts of water into drain,
enough to ll drain trap and line.
Crankcase Heater (if used)
Some models may be equipped with a crankcase heater
to prevent excessive migration of liquid refrigerant into the
compressor during o cycles. Power must be maintained
to the unit to keep this feature active.
Except as required for safety while servicing, do not open
the system disconnect switch.
Figure 5.
Page 14 of 22 507635-05Issue 2245
Heater Kit Accessory (if used)
The unit is fully equipped for operation without auxiliary
heat. A heater kit accessory may also be used. To install
the heater kit accessory (see Figure 5):
1. Disconnect the power and open the main control
access.
2. Disconnect the plug separating the high voltage wire
harness. Remove the high voltage wire harness plug
and discard.
3. Remove the heater blocko by removing the four
screws holding it in place.
4. Insert the heater into the control panel and fasten in
the same mounting holes.
5. Plug the heater wiring harness into the wire harness
on the control assembly. Field wiring of the auxiliary
heater is separate from the unit power supply. Wire the
power supply wiring for the heater to the appropriate
connections on the heater kit.
Sequence of Operation
Blower Control
Units are equipped with a variable speed motor that is
capable of maintaining a specied CFM throughout the
external static range. A particular CFM can be obtained by
positioning jumpers (COOL, HEAT, and ADJUST) on the
blower control. The HEAT and COOL jumpers are labeled
A, B, C and D. Each of the numbers corresponds with an
air volume (CFM) setting. The ADJUST jumper is labeled
Test, -, +, and Norm. The + and - pin settings are used to
add or subtract a percentage of the CFM selected. The
Test jumper is used to operate the motor in the test mode.
Figure 7 shows the blower control.
The CFM LED located on the blower control ashes one
time per 100 cfm to indicate selected blower speed. For
example, if the unit is operating at 1200 CFM, the CFM
LED will ash 12 times. If the CFM is 1150, the CFM
LED will ash 11 full times plus one fast or half ash. At
times, the light may appear to icker or glow. This takes
place when the control is communicating with the motor
between cycles. This is normal operation. Read through
the jumper settings section before adjusting the jumper to
obtain the appropriate blower speed. To change jumper
positions, gently pull the jumper o the pins and place it
on the desired set of pins. The following section outlines
the dierent jumper selections available and conditions
associated with each one. Refer to Figure 7.
From the engineering handbook and/or specication
sheet, determine which row most closely matches the
desired CFM. Once a specic row has been chosen (+,
NORMAL, or -), CFM volumes from other rows cannot be
used. Below are descriptions of the jumper selections.
The variable speed motor slowly ramps up to and down
from the selected air ow during both cooling and heating
demand. This minimizes noise and eliminates the initial
blast of air when the blower is initially energized.
ADJUST
The ADJUST pins allow the motor to run at normal speed,
approximately 10 percent higher, or approximately 10
percent lower than normal speed.
The TEST pin is available to bypass the blower control
and run the motor at approximately 70 percent to make
sure that the motor is operational. This is used mainly in
troubleshooting. The G terminal must be energized for the
motor to run.
COOL
The COOL jumper is used to determine the CFM during
cooling operation. In AC units, this jumper selection is
activated for cooling when Y1/Y2 is energized. In heat
pump units, the selection is activated for cooling when Y1/
Y2 and O are energized.
The blower motor runs at 80 percent of the selected air
ow for the rst 7-1/2 minutes of each cooling demand.
This feature allows for greater humidity removal and saves
energy.
Figure 7.
507635-05 Page 15 of 22Issue 2245
In the cooling mode, the blower control delays blower
operation for 5 seconds after the compressor starts. The
blower continues to operate for 90 seconds after the
compressor is de-energized. The delay is 5 minutes on the
rst start.
HEAT
The HEAT jumper is used to determine CFM during electric
heat operation only. These jumper selections are activated
only when W1/W2 is energized.
CONTINUOUS FAN
When the thermostat is set for “Continuous Fan” operation
and there is no demand for heating or cooling, the blower
control will provide 50 percent of the COOL CFM selected.
DEHUMIDIFICATION
The blower control includes an HUM terminal, which
provides for connection of a humidistat. The JV1 resistor
on the blower control must be cut to activate the HUM
terminal. The humidistat must be wired to open on humidity
rise. When the dehumidication circuit is used, the variable
speed motor will reduce the selected air ow rate by 25
percent when humidity levels are high. An LED (D1) lights
when the blower is operating in the dehumidication mode.
Cooling System
The cooling system is factory-charged with HFC-R-410A.
The compressor is hermetically sealed and base-mounted
with rubber-insulated bolts.
Cooling
When the thermostat calls for cooling, R is closed to Y1
and O (see the wiring diagrams starting on Page 21).
This action completes the low voltage control circuit,
energizing the compressor, condenser fan motor, and
blower motor. Second-stage cooling is initiated by the
thermostat energizing Y2 in AC units and Y2 and O in heat
pumps.
Unit compressors have internal protection. In the event there
is an abnormal rise in the temperature of the compressor,
the protector will open and cause the compressor to stop.
The thermostat automatically closes the R to G circuit,
which brings on the indoor blower. Upon satisfying cooling
demand, the thermostat will open the above circuits and
open the main contactor, stopping the compressor and
outdoor fan. If the unit is equipped with a delay timer, the
blower will continue to operate for 60 to 90 seconds, which
improves system eciency.
Heating - Heat Pump Stage
Upon heating demand, the thermostat closes circuit R to
Y1, which closes the unit contactor, starting the compressor
and outdoor fan. Second-stage heating is initiated when
the thermostat energizes Y2, or when the outdoor ambient
temperature is below the lock-in temperature (see Second-
Stage Lock-In section). The reversing valve is not energized
in the heating mode. The thermostat again automatically
brings on the indoor fan at the same time. Upon satisfying
heating demand, the thermostat opens above circuits and
stops unit operation.
NOTE: O is de-energized in heating mode.
Heating - Auxiliary Electric Heat
Upon heating demand for auxiliary electric heat, the
thermostat closes circuit R to W, which energizes the
heater sequencers as well as the indoor blower. Upon
satisfying auxiliary heat demand, the thermostat opens
above circuits and heating elements sequence o; the
blower continues to operate until all heating elements have
turned o.
Auxiliary electric heat can be staged using W1, W2 on 10,
15 and 20 kW models. Staged wiring diagrams are included
with the installation instructions of electric heater kits.
Heating - Emergency Mode
When the thermostat calls for emergency heat, the R to W
circuit is closed. Upon satisfying heat demand, the circuit
is open and the blower continues to operate through an o
delay period. The primary function of emergency mode is
to provide emergency heat should the heat pump operation
fail.
Defrost System
Defrost System
Demand Defrost System
The demand defrost system measures dierential
temperatures to detect when the system is performing
poorly because of ice build-up on the outdoor coil. The
system “self-calibrates” when the defrost system starts
and after each system defrost cycle. The demand defrost
components on the control board are listed below.
NOTE: The demand defrost system 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 board initiates defrost cycles.
Defrost System Sensors
Sensors connect to the defrost board through a eld–
replaceable harness assembly that plugs into the board.
Through the sensors, the board detects outdoor ambient
and coil fault conditions. As the detected temperature
changes, the resistance across the sensor changes.
Sensor resistance values can be checked by ohming
across pins.
NOTE: When checking the ohms across a sensor, be
aware that a sensor showing a resistance value that is not
Page 16 of 22 507635-05Issue 2245
within the range shown, 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 needs to
be replaced.
Sensor Temperature
Range °F (°C)
Red LED
(DS1)
Pins / Wire
Color
Outdoor
(ambient)
-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)
NOTE: Sensor resistance decreases as sensed temperature
increases.
Table 3. Sensor Temp. / Resistance Range
Figure 6. Defrost Control Board
(2-Ton Units)
TEST PINS
DEFROST
TERMINATION
PIN SETTINGS
SENSOR
PLUG-IN
(COIL &
AMBIENT
SENSORS)
DELAY PINS
REVERSING
VALVE
PRESSURE
SWITCH
CIRCUIT
CONNECTIONS
LOW
AMBIENT
THERMOSTAT
PINS
DIAGNOSTIC
LEDs
24V TERMINAL
STRIP
CONNECTIONS
Note -
Component
Locations Vary
by Board
Manufacturer
Coil Sensor
The 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 board 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.
NOTE: The coil temperature probe is designed with a
spring clip to allow mounting to the outside coil tubing. Coil
sensor location is important for proper defrost operation.
Ambient Sensor
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 board will not
perform demand defrost operation. The board 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.
NOTE: Within a single room thermostat demand, if 5-strikes
occur, the board will lockout the unit. Control board 24 volt
power “R” must be cycled “OFF” or the “TEST” pins on
board must be shorted between 1 to 2 seconds to reset
the board.
Defrost Temperature Termination Shunt (Jumper)
Pins
The defrost board 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 the temperature shunt is not installed,
the default termination temperature is 90°F (32°C).
Delay Mode
The defrost system has a eld-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
o for 30 seconds going in and out of the defrost mode.
Units are shipped with jumper installed on DELAY pins.
NOTE: The 30 second compressor delay feature (known
as the quiet shift) must be deactivated during any unit
performance testing. The feature is deactivated by
removing the jumper located on the compressor delay pins
on the control board mounted inside the unit control box.
This feature is optional for the homeowner, but may impact
testing performance.
Defrost Operation
The defrost control system has three basic operational
modes: normal, calibration, and defrost.
• Normal Mode—The demand defrost system 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 Mode—The board is considered
uncalibrated when power is applied to the board,
after cool mode operation, or if the coil temperature
exceeds the termination temperature when it is in heat
mode.
Calibration of the board 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 dierential which is required to allow a
defrost cycle.
507635-05 Page 17 of 22Issue 2245
• Defrost Mode—The following paragraphs provide a
detailed description of the defrost system operation.
Defrost Cycles
The control board initiates a defrost cycle based on either
frost detection or time.
• Frost Detection—If the compressor runs longer than
30 minutes and the actual dierence between the
clear coil and frosted coil temperatures exceeds the
maximum dierence allowed by the control, a defrost
cycle will be initiated.
IMPORTANT - The control board will allow a greater
accumulation of frost and will initiate fewer defrost
cycles than a time/ temperature defrost system.
• Time—If 6 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 control
board will initiate a defrost cycle.
Actuation
When the reversing valve is de-energized, the Y1 circuit is
energized, and the coil temperature is below 35°F (2°C),
the board logs the compressor run time. If the board 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).
Calibration success depends on stable system
temperatures during the 20-minute calibration period. If
the board fails to calibrate, another defrost cycle will be
initiated after 45 minutes of heating mode compressor
run time. Once the control board is calibrated, it initiates
a demand defrost cycle when the dierence between
the clear coil and frosted coil temperatures exceeds the
maximum dierence allowed by the control OR after 6
hours of heating mode compressor run time has been
logged since the last defrost cycle.
NOTE: If ambient or coil fault is detected, the board will not
execute the “TEST” mode.
Termination
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.
5-Strike Lockout Feature
The internal control logic of the board 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 fth time during the current Y1 (Input),
the control will enter a lockout condition.
The 5-strike pressure switch lockout condition can be reset
by cycling OFF the 24-volt power to the control board or by
shorting the TEST pins between 1 and 2 seconds. All timer
functions (run times) will also be reset.
If a pressure switch opens while the Y1 Out line is engaged,
a 5-minute short cycle will occur after the switch closes.
Page 18 of 22 507635-05Issue 2245
Diagnostic LEDs
The defrost board uses two LEDs for diagnostics. The
LEDs ash a specic sequence according to the condition
as shown in Table 4.
Defrost Board Diagnostic LEDs
Green LED
(DS2)
Red LED
(DS1) Condition
OFF OFF No Power to Control
Simultaneous Slow FLASH Normal Operation /
Power to Control
Alternating Slow FLASH 5-min Anti-Short-Cycle Delay
ON Slow FLASH Low Pressure Switch Ignored
(Low Ambient)
Fault & Lockout Codes
OFF Slow FLASH Low Pressure Switch Fault
OFF ON Low Pressure Switch Lockout
Slow FLASH OFF High Pressure Switch Fault
ON OFF High Pressure Switch Lockout
Table 4. Defrost Control (CMC1) Diagnostic LEDs
System Performance
This equipment is a self-contained, factory optimized
refrigerant system, and should not require adjustments to
system charge when properly installed. If unit performance
is questioned, perform the following checks.
Ensure unit is installed per manufacturer’s instructions and
that line voltage and air ow is correct. Refer to Table 5
through Table 7 for proper performance value. The indoor
metering device varies by model.
If the measured performance value varies from table value
allowance, check internal seals, service panels and duct
work for air leaks, as well as restrictions and blower speed
settings. If unit performance remains questionable, remove
system charge, evacuate to 500 microns, and weigh in
refrigerant to nameplate charge. It is critical that the exact
charge is re-installed. Failure to comply will compromise
system performance.
If unit performance is still questionable, check for
refrigerant-related problems, such as blocked coil or
circuits, malfunctioning metering device or other system
components.
Maintenance
Before performing maintenance operations on the
system, shut o all electrical power to the unit. Turn o
accessory heater power switch if applicable. Electrical
shock could cause personal injury or death.
WARNING
Periodic inspection and maintenance normally consists of
changing or cleaning the lters and cleaning the evaporator
coil. On occasion, other components may also require
cleaning.
Filters
Filters are not supplied with the unit. Inspect once a month.
Replace disposable or clean permanent type as necessary.
Do not replace permanent type with disposable.
Motors
Indoor and outdoor fan and vent motors are permanently
lubricated and require no maintenance.
Some models may be equipped with a permanent magnet,
constant torque indoor blower motor. These motors remain
energized and are controlled by 24V signals. For high
static applications, use tap 3 for cooling speed and tap 5
for heating speed. Refer to the heater installation label for
limitations to blower tap selection on heating speeds.
Evaporator Coil
Dirt and debris should not be allowed to accumulate on
the evaporator coil surface or other parts in the air circuit.
Cleaning should be as often as necessary to keep coil
clean. Use a brush, vacuum cleaner attachment, or other
suitable means. If water is used to clean the coil, be sure
the power to unit is shut o prior to cleaning. Care should
be used when cleaning the coil so that the coil ns are
not damaged.
Do not permit the hot condenser air discharge to be
obstructed by overhanging structures or shrubs.
Condenser Coil
Clean condenser coil annually with water and inspect
monthly during the cooling season.
Condenser coil may need to be cleaned at startup in
case oil from the manufacturing process is found on the
condenser coil.
507635-05 Page 19 of 22Issue 2245
80 DB / 67 WB Deg. Return
Air Air Temperature Entering Evaporator Coil, Degree F
COOLING
INPUT
(1000 BTU)
Pressure 65° 70° 75° 80° 85° 90° 95° 100° 105° 110° 115°
24
Suction
148 147 147 147 147 148 149 151 153 155 157
36 140 141 142 143 144 145 146 147 149 150 152
48 143 143 143 143 143 144 146 148 150 152 155
60 139 139 138 139 139 140 142 143 145 147 150
24
Liquid
212 238 264 289 313 337 360 382 404 425 445
36 248 267 287 308 331 355 380 407 435 465 496
48 252 273 295 318 342 366 392 419 446 475 504
60 258 277 298 319 341 365 391 415 442 470 499
Table 5. Cooling Performance - AC Models
80 DB / 67 WB Deg. Return
Air Air Temperature Entering Evaporator Coil, Degree F
COOLING
INPUT
(1000 BTU)
Pressure 65° 70° 75° 80° 85° 90° 95° 100° 105° 110° 115°
24
Suction
144 145 146 147 148 149 151 153 154 156 159
36 136 138 139 140 142 144 146 147 149 152 154
48 143 141 141 141 141 142 144 146 148 151 155
60 138 138 139 139 140 141 143 144 145 147 149
24
Liquid
232 251 270 291 312 335 358 382 407 434 461
36 242 260 279 299 321 344 369 394 422 450 480
48 238 257 277 299 321 344 368 394 420 448 476
60 247 267 288 310 333 357 381 408 434 462 491
Table 6. Cooling Performance - HP / DF Models
Page 20 of 22 507635-05Issue 2245
70 Deg. F Return Air Air Temperature Entering Evaporator Coil, Degree F
COOLING
INPUT
(1000 BTU)
Pressure 0°5°10°17°20°25°35°40°47°50°55°60°
24
Suction
39 43 48 56 60 67 82 90 102 108 118 129
36 27 32 38 46 50 56 71 79 91 96 106 115
48 34 38 43 50 54 61 76 84 97 103 113 124
60 36 41 46 55 58 65 80 87 99 104 113 123
24
Liquid
309 304 300 299 299 301 310 317 330 336 348 362
36 284 292 300 311 316 324 341 350 363 369 378 388
48 272 278 284 294 299 308 328 339 356 364 377 392
60 326 325 326 330 332 337 352 361 374 384 397 412
Table 7. Heating Performance - HP / DF Models
This manual suits for next models
1
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