Allied Air 4SHP13 series User manual

506272-01 Page 1 of 26Issue 0921
The equipment covered in this manual is to be installed by trained and experienced
service and installation technicians. Improper installation, modification, service, or
use can cause electrical shock, fire, explosion, or other conditions which may cause
personal injury, death, or property damage. Use appropriate safety gear including
safety glasses and gloves when installing this equipment.
WARNING
Risk of electrical shock. Disconnect all remote power
supplies before installing or servicing any portion of the
system. Failuretodisconnectpowersuppliescanresult
in property damage, personal injury, or death.
WARNING
Installationandservicingofairconditioningequipment
canbe hazardous due tointernalrefrigerant pressure
and live electrical components. Only trained and
qualified service personnel should install or service
thisequipment. Installationandserviceperformed by
unqualified persons can result in property damage,
personal injury, or death.
WARNING
Sharp metal edges can cause injury. When installing
the unit, use care to avoid sharp edges.
WARNING
TABLE OF CONTENTS
INSTALLATION ....................................................2
START-UP..........................................................12
OPERATION ......................................................17
MAINTENANCE .................................................18
HOMEOWNER INFORMATION .........................19
WIRING DIAGRAM ............................................22
WARRANTY.......................................................26
ManufacturedBy
AlliedAir Enterprises Inc.
A Lennox International Inc. Company
215 Metropolitan Drive
West Columbia, SC 29170
*506272-01*
Save these instructions for future reference
INSTALLATION AND MAINTENANCE INSTRUCTIONS
4SHP13 Series
Split System Heat Pump

Page 2 of 26 506272-01Issue 0921
INSTALLATION Check the unit rating plate to confirm specifications are
as ordered.
Location of Unit
Outdoor units operate under a wide range of weather
conditions; therefore, multiple factors must be considered
when positioning the unit. The unit must be positioned to
give adequate clearances for sufficient airflow and
serviceing. Refer to Figure 1 for installation clearances.
General
Read this entire instruction manual, as well as the
instructions supplied in separate equipment, before
starting the installation. Observe and follow all
warnings, cautions, instructional labels, and tags.
Failure to comply with these instructions could result
in an unsafe condition and/or premature component
failure.
These instructions are intended as a general guide only for
usebyqualifiedpersonneland donotsupersede anynational
orlocalcodes in any way. Theinstallationmustcomplywith
all provincial, state, and local codes as well as the National
ElectricalCode (U.S.)orCanadianElectricalCode(Canada).
Compliance should be determined prior to installation.
4SHP13 condensing units use R-410A which is an ozone-
friendly HFC refrigerant. The unit must be installed with a
matching indoor coil and line set. Afilter drier approved for
use with R-410Ais installed in the unit.
Whenservicing or repairingHVAC components, ensure the
fastenersareappropriately tightened. Table1 shows torque
values for fasteners.
• Place a sound-absorbing material, such as Isomode,
under the unit if it will be installed in a location or position
that will transmit sound or vibration to the living area or
adjacent buildings.
• Install the unit high enough above the ground or roof to
allowadequatedrainage of defrost water andpreventice
buildup.
• In heavy snow areas, do no locate the unit where drifting
snowwill occur. Theunit baseshouldbe elevated above
the depth of average snows.
NOTE: Elevation of the unit may be accomplished by
constructing a frame using suitable materials. If a
support frame is constructed, it must not block drain
holes in unit base.
• Wheninstalledin areas where lowambient temperatures
exist, locate unit so winter prevailing winds do not blow
directly into outdoor coil.
Inspection of Shipment
Upon receipt of equipment, carefully inspect it for possible
shippingdamage. If damage is found, itshouldbe noted on
the carrier’s freight bill. Take special care to examine the
unit inside the carton if the carton is damaged. Any
concealed damage discovered should be reported to the
last carrier immediately, preferably in writing, and should
include a request for inspection by the carrier’s agent.
If any damages are discovered and reported to the carrier
DO NOT INSTALLTHE UNIT, as claim may be denied.
Torque Table
Table 1
Compressor Bolts 90 in. lbs.
#10 Machine Screws 28 in. lbs.
#8 Machine Screws 16 in. lbs.
Sheet Metal Screws 16 in. lbs.
Service Port Caps 8 ft. lbs.
Stem Caps 8 ft. lbs.
Fastener Torque
Figure 1
Installation Clearances
* A service clearance of 30" must be maintained on one of the
sides adjacent to the control box. Clearance to one of the other
three sides must be 36". Clearance to one of the remaining two
sides may be 12" and the final side may be 6".
A clearance of 24" must be maintained between units.
48" clearance required on top of unit. Maximum soffit overhang is
36".

506272-01 Page 3 of 26Issue 0921
If the 4SHP13 unit is being installed with a new indoor coil
and line set, the refrigerant connections should be made as
outlined in this section. If an existing line set and/or indoor
coilwillbe used to completethesystem,refer to this section
aswellasthesectionthatfollows entitled: Flushing Existing
Line Set and Indoor Coil.
Ifthisunitisbeingmatchedwithanapproved linesetorindoor
coil which was previously charged with R22 refrigerant, the
line set and coil must be flushed prior to installation. If the
unit is being used with an existing indoor coil which was
equippedwith a liquidlinewhichservedasa metering device
(RFCI),theliquidlinemust bereplacedpriortotheinstallation
of the 4SHP13 unit.
Refrigerant can be harmful if inhaled. Refrigerant must
always be used and recovered responsibly. Incorrect or
irresponsibleuseofrefrigerantcanresultinpersonalinjury
ordeath.
WARNING
• Locateunit away from overhangingrooflineswhichwould
allow water or ice to drop on, or in front of, coil or into
unit.
Slab Mounting
When installing a unit at grade level, install on level slab
high enough above grade so that water from higher ground
will not collect around the u nit (see Figure 2).
Roof Mounting
Install unit at a minimum of 6” above surface of the roof to
avoid ice buildup around the unit. Locate the unit above a
loard bearing wall or area of the roof that can adequately
supportthe unit. Consult localcodesforrooftopapplications.
Electrical Wiring
Allfieldwiringmust be done in accordance withthe National
Electrical Code (NEC) recommendations, Canadian
Electrical Code (CEC) and CSA Standards, or local codes,
whereapplicable.
Unit must be grounded in accordance with national and
localcodes. Failureto ground unit properlycanresultin
personal injury or death.
WARNING
Refer to the furnace or blower coil installation instructions
for additional wiring application diagrams and refer to unit
rating plate for minimum circuit ampacity and maximum
overcurrent protection size.
1. Install line voltage power supply to unit from a properly
sized disconnect switch. Any excess high voltage field
wiring should be trimmed or secured away from the low
voltage field wiring.
2.Ground unitatunitdisconnectswitchorto anearthground.
To facilitate conduit, a hole is in the bottom of the control
box. Connect conduit to the control box using a proper
conduitfitting. Units areapprovedforuse onlywithcopper
conductors. 24VClass II circuit connections aremadein
the low voltage junction box. A complete unit wiring
diagram is located inside the unit control box cover (see
also page 23 of this instruction).
3.Installroomthermostatonaninsidewallthatisnotsubject
to drafts, direct sunshine, or other heat sources.
4. Install low voltage wiring from outdoor to indoor unit and
from thermostat to indoor unit (see Figure 3 on page 4).
5. Do not bundle any excess 24V control wire inside control
box. Runcontrol wirethroughinstalledwiretieandtighten
wiretieto provide low voltagestrainrelief and to maintain
separation of filed-installed low and high voltage circuits.
Line voltage is present at all components when unit is
not in operation on units with single pole contractors.
Disconnect all remote electric power supplies before
opening access panel. Unit may have multiple power
supplies. Failuretodisconnectallpowersupplies could
result in personal injury or death.
WARNING
Refrigerant Piping
Figure 2
Slab Mounting
Discharge Air
Mounting Slab
Ground Level
Building
Structure

Page 4 of 26 506272-01Issue 0921
Field refrigerant piping consists of liquid and suction lines
from the outdoor unit (sweat connections) to the indoor coil
(flare or sweat connections).
Select line set diameters from Table 2 to ensure that oil
returns to the compressor. Size vertical suction riser to
maintain minimum velocity at minimum capacity.
Recommended line length is 50' or less. If more than 50'
line set is required, contact Technical Services.
Table2showsthediametersforlinesetsupto100'although
vertical lift applications and trapping requirements need to
be reviewed with Technical Services for line sets over 50'.
Polyolester (POE) oils used with R-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 ready to make connections.
WARNING
Thermostat Designations
(Some connections may not apply. Refer to
specific thermostat and indoor unit.)
WithoutAuxiliary Heat
WithAuxiliary Heat
Do not connect C (common) connection between indoor unit and
thermostat except when required by the indoor thermostat. Refer
to thermostat installation instructions. C (common) connection
betweenindoorunit and outdoorunitrequired for properoperation.
Figure 3
Refrigerant Line Set Diameters (in.)
For installations eceeding 50’, contact Technical
Services at [phone].
Table 2

506272-01 Page 5 of 26Issue 0921
Line Set Isolation
Illustrationsonthefollowingpagesdemonstrateprocedures
which ensure proper refrigerant line set isolation. Figure 5
shows how to install line sets on horizontal runs. Figure 6
shows how to make a transition from horizontal to vertical
and Figure 7 on page 6 shows how to install line sets on
vertical runs.
Installing Refrigerant Line
During the installation of an air conditioning system, it is
important to properly isolate the refrigerant line to prevent
unnecessary vibration. Line set contact with the structure
(wall, ceiling, or floor) may cause objectionable noise when
vibration is translated into sound. As a result, more energy
or vibration can be expected. Close attention to line set
isolation must be observed. If refrigeration lines are routed
through a wall, seal and isolate the opening so vibration is
not transmitted to the building.
Following are some points to consider when placing and
installing a high-efficiency outdoor unit:
Placement
Beaware thatsomelocalitiesare adopting soundordinances
based on how noisy the unit is at the neighbor’s home, not
at the original installation. Install the unit as far as possible
fromtheproperty line. When possible, donotinstalltheunit
directly outside a bedroom window. Glass has a very high
level of sound transmission. Figure 4 shows how to place
the outdoor unit and line set to reduce line set vibration.
Figure 5
Refrigerant Line Sets: Installing Horizontal Runs
To hang line set from joist or rafter,
use either metal strapping material
or anchored heavy nylon wire ties.
Strapping Material
(around vapor line only)
8’
8’
Tape or Wire Tie
Strap the vapor line to the joist or rafter
at 8 intervals then strap the liquid line
to the vapor line.
’
Floor Joist or
Roof Rafter
Metal Sleeve
Floor Joist or Roof Rafter
Tape or Wire Tie
Wire Tie
(around vapor line only)
Outside Unit Placement and Installation
Figure 4
Install unit away
from windows
Two 90° elbows installed in lineset
will reduce lineset vibration

Page 6 of 26 506272-01Issue 0921
Figure 6
Refrigerant Line Sets: Transition from Vertical to Horizontal
Anchored
Heavy Nylon
Wire Tie
Wall
Stud
Metal Sleeve Vapor Line Wrapped
in Armaflex
–
Liquid Line
Wall
Stud
Automotive
Muffler-Type
Hanger
Strap Liquid
Line to Vapor
Line
Metal Sleeve Vapor Line Wrapped
in Armaflex
–
Liquid Line
Strap Liquid
Line to Vapor
Line
Figure 7
Refrigerant Line Sets: Installing Vertical Runs (new construction shown)
Outside Wall
Wood Block
Between Studs
IMPORTANT: Refrigerant
lines must not contact wall.
Vapor Line Liquid Line
Wire Tie
Inside Wall
Strap
Sleeve
Wire Tie
Wire Tie
Strap
Wood Block
Sleeve
Vapor Line Wrapped
with Armaflex
Liquid Line
Caulk
PVC Pipe Fiberglass
Insulation
Outside Wall
IMPORTANT:
Refrigerant
lines must not
contact structure.
NOTE: Similar installation practices
should be used if line set is to be
installed on exterior of outside wall.

506272-01 Page 7 of 26Issue 0921
Brazing Connection Procedure
1. Cut ends of refrigerant lines square (free from nicks or
dents). Debur the ends. The pipe must remain round;
do not pinch end of line.
2. Beforemakinglinesetconnections,usedrynitrogentopurge
therefrigerantpiping. Thiswillhelptopreventoxidationand
the introduction of moisture into the system.
3. Use silver alloy brazing rods (5% or 6% silver alloy for
copper-to-copperbrazingor45%silveralloyforcopper-
to-brass or copper-to-steel brazing) which are rated for
use with R-410A refrigerant.
4. Remove the Schrader core assemblies before brazing
to protect them from damage due to extreme heat.
Replace the cores when brazing is complete.
5. Remove light maroon washers from service valves and
shieldlightmaroonstickerstoprotectthemduringbrazing.
Wrapawetclotharoundthevalvebody and copper tube
stub to protect it from heat damage.
6. Braze the line set to the service valve. Quench the joints
with water or a wet cloth to prevent heat damage to the
valve core and opening port. The tube end must stay
bottomedinthefitting duringfinalassembly toensure
proper seating, sealing, and rigidity.
7. Installthe fixedorifice(or thermal expansionvalve which
issoldseparatelyand which is approved forusewith R-
410A refrigerant) in the liquid line at the indoor coil (see
Refrigerant Metering Device on page 8).
Flushing Existing Line Set and Indoor Coil
This procedure should not be performed on systems
which contain contaminants, such as compressor burn
out.
Whenflushingexistinglinesetand/orindoorcoil,besureto
empty all existing traps. Residual mineral oil can act as an
insulator, preventing proper heat transfer. It can also clog
thethermalexpansionvalve,reducingsystemperformance
andcapacity. Failuretoproperlyflushsystemasexplained
inthese instructions willvoid warranty.
CAUTION
Required Equipment
The following equipment is needed to flush the existing line
setand indoor coil (seeFigure8): Twoclean R-22 recovery
bottles, an oil-less recovery machine with a “pump down”
feature, and two sets of gauges (one for use with R-22 and
one for use with R-410A).
Figure 8
Flushing Connections
Note: The inverted R22 cylinder must contain at least the
same amount of refrigerant as was recovered from
the existing system.

Page 8 of 26 506272-01Issue 0921
5. Removethepressure tapvalvecoresfrom the 4SCU13
unit’s service valves. Connect an R-22 cylinder with
clean refrigerant to the suction service valve. Connect
the R-22 gauge set to the liquid line valve and connect
a recovery machine with an empty recovery tank to the
gauge set.
6. Set the recovery machine for liquid recovery and start
the recovery machine. Open the gauge set valves to
allow the recovery machine to pull a vacuum on the
existing system line set and indoor coil.
7. Invert the cylinder of clean R-22 and open its valve to
allow liquid refrigerant to flow into the system through
thesuctionline valve. Allow the refrigeranttopassfrom
the cylinder and through the line set and the indoor coil
before it enters the recovery machine.
8. After all of the liquid refrigerant has been recovered,
switch the recovery machine to vapor recovery so that
all of the R-22 vapor is recovered. Allow the recovery
machine to pull a vacuum on the system.
NOTE: A single system flush should remove all of the
mineral oil from the existing refrigerant lines and indoor
coil. A second flushing may be done (using clean
refrigerant) if insufficient amounts of mineral oil were
removedduring thefirstflush. Aftereach system flush,
allow the recovery machine to pull a vacuum on the
system at the end of the procedure.
9. Close the valve on the inverted R-22 cylinder and the
gauge set valves. Pump the remaining refrigerant out
of the recovery machine and turn the machine off.
10. Use nitrogen to break the vacuum on the refrigerant lines
and indoor coil before removing the recovery machine,
gauges,andR-22refrigerantdrum. Re-installpressuretap
valve cores into the 4SCU13 unit’s service valves.
11. Install the factory-supplied fixed orifice (or thermal
expansion valve approved for use with R-410A
refrigerant) in the liquid line at the indoor coil.
Refrigerant Metering Device
4SCU13 units are designed for use with either fixed orifice
or TXV systems. Refer to the appropriate following section
for information on installing the chosen refrigerant metering
device.
Fixed Orifice Systems
4SCU13 units are shipped with a fixed orifice refrigerant
metering device. See specification sheets for the proper
fixed orifice size for each unit. In nonstandard applications,
the fixed orifice provided with the indoor unit may not be
Flushing Procedure
IMPORTANT: The line set and/or indoor coil must be
flushed with at least the same amount of refrigerant that
previously charged the system. Check the charge in
the flushing cylinder before flushing the unit.
1. Removeexisting R-22 refrigerant usingtheappropriate
procedure.
If the existing outdoor unit is not equipped with shutoff
valves, or if the unit is not operational AND the existing
R-22 refrigerant will be used to flush the system:
Disconnectallpowertotheexistingoutdoorunit.Connect
theexistingunit,acleanrecoverycylinder,andtherecovery
machine according to the instructions provided with the
recovery machine. Remove all R-22 refrigerant from the
existing system. Refer to the gauges after shutdown to
confirm that the entire system is completely void of
refrigerant. Disconnect the liquid and suction lines from
the existing outdoor unit.
If the existing outdoor unit is equipped with manual
shutoffvalvesANDnew R-22refrigerant will be used to
flush the system:
Startthe existing R-22refrigerant system in coolingmode
andclose the liquid line valve. Pumpall the existingR-22
refrigerant back into the outdoor unit.
(Itmaybenecessarytobypassthelowpressureswitches
to ensure complete refrigerant evacuation.)
When the low side system pressures reach 0 psig, close
thesuctionlinevalve. Disconnectallpowertotheexisting
outdoorunit.Refertothegaugesaftershutdowntoconfirm
that the valves are not allowing refrigerant to flow back
into the low side of the system. Disconnect the liquid and
suction lines from the existing outdoor unit.
2. Remove the existing outdoor unit. Set the new R-410A
unitandfollowthebrazingconnectionprocedureoutlined
previously on this page to make line set connections.
Do not install the R-410A thermal expansion valve
at this time.
3. Makelowvoltageandlinevoltageconnections tothenew
outdoorunit. Do not turn on power to the unit or open
the outdoor unit service valves at this time.
4. RemovetheexistingR-22refrigerant flow control orifice
or thermal expansion valve before continuing with
flushing procedures. R-22 flow control devices are not
approved for use with R-410A refrigerant and may
prevent proper flushing. Use a field-provided fitting to
reconnect the lines.

506272-01 Page 9 of 26Issue 0921
To install an expansion valve (see Figure 9):
1. Separatethe distributor assembly andremovethe piston
orifice and used teflon seal. Insert nozzle end of the
expansion valve along with a new teflon seal into the
distributorandtightento20–30ft.lbs. Usebackupwrench
onallwrenchflats. Overtighteningwill crushthe teflon
seal and may cause a leak.
2. Attach liquid line portion of distributor assembly along
with new teflon seal to the inlet of the expansion valve.
Tighten to 20 – 30 ft. lbs. Use backup wrench on all
wrenchflats. Overtightening will crushthe teflon seal
and may cause a leak.
3. Connecttheexternal equalizer line totheequalizer port
on the suction line and tighten to 8 ft. lbs.
4. Strap the superheat sensing bulb to the suction header.
If installing an expansion valve on an indoor coil that
previouslyused a fixed orifice,besuretoremove the existing
fixedorifice. Failuretoremove a fixed orifice when installing
an expansion valve to the indoor coil will result in improper
operation and damage to the system.
Manifold Guage Set
Manifoldgaugesetsusedwithsystemschargedwith R410A
refrigerant must be capable of handling the higher system
operating pressures. The gauges should be rated for use
with pressures 0 – 800 on the high side and a low side of
30" vacuum to 250 psi with dampened speed to 500 psi.
Gauge hoses must be rated for use at up to 800 psi of
pressure with a 4000 psi burst rating.
Liquid and SuctionLine Service Valves
The liquid line and suction line service valves and service
ports are used for leak testing, evacuating, charging, and
checking charge.
appropriately sized to be matched with the 4SCU13 unit. If
necessary, replace the existing indoor unit fixed orifice with
theorifice supplied with the 4SCU13unit. Placethesupplied
fixed orifice sticker on the indoor cabinet after installation.
Figure 9 shows how to install the replacement fixed orifice.
Do not twist cap tubes when loosening the seal nut from the
orifice housing. Use wrench to back up the distributor.
Expansion Valve Systems
Expansion valves equipped with Chatleff-type fittings are
available from the manufacturer. See Table 4 for proper
TXV for each unit.
Fixed Orifice Data
* 4SHP13-18 models are designed for use with TXV systems
only.
Model * Part
Number
Drill
Size
4SHP13-24
4SHP13-30
4SHP13-36
4SHP13-42
4SHP13-48
4SHP13-60
100484-09
100484-15
100484-16
100484-23
100484-30
100484-37
.059
.065
.067
.074
.082
.090
Table 3
Metering Device Installation
Figure 9
Ifnecessary,removeR22flowcontroldevice(fixed
orifice/thermal expansion valve) from existing line
set before installing R-410A approved orifice or
expansion valve.
Table 4
TXV Data
Model Part
Number
4SHP13-18.-24, -30
4SHP13-36, -42
4SHP13-48, -60
H4TXV01
H4TXV02
H4TXV03

Page 10 of 26 506272-01Issue 0921
Leak Testing
After the line set has been connected to the indoor and
outdoor units, the line set connections and indoor unit must
be checked for leaks.
Using an Electronic Leak Detector
1. Connect the high pressure hose of the manifold gauge
set to the suction valve service port. (Normally the high
pressure hose is connected to the liquid line port;
To Access the Schrader Port:
1. Remove the service port cap with an adjustable wrench.
2. Connect gauge to the service port.
3. When testing is completed, replace service port cap.
Tighten finger tight, then an additional 1/6 turn.
To Open Liquid or Suction Line Service Valve:
1. Remove stem cap with an adjustable wrench.
2. Useaservicewrench with a hex-head extension to back
thestem out counterclockwise as far asitwill go. Use a
3/16" hex head extension for liquid line service valves
and a 5/16" extension for suction line service valves.
3. Replace the stem cap. Tighten finger tight, then tighten
an additional 1/6 turn.
To Close Liquid or Suction 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.
3. Replace the stem cap. Tighten finger tight, then tighten
an additional 1/6 turn.
Suction Line (Ball Type) Service Valve
Suctionline(balltype)servicevalves function the same way
astheothervalves; the differenceis in theconstruction(see
Figure 11).
The ball valve is equipped with a service port with a factory-
installed Schrader valve. A service port cap protects the
Schradervalvefromcontaminationandservesasthe primary
seal.
Eachvalveisequippedwithaserviceportwhichhasafactory-
installed Schrader valve. A service port cap protects the
Schradervalve from contamination and servesasthe primary
leak seal.
Figure 10
Service Valve
Valve Closed
Valve Open
Ball Type Service Valve
(Valve Open)
Figure 11
Use adjustable wrench. To open, rotate stem
counterclockwise 1/4 turn (90°). To close, rotate
stem clockwise 1/4 turn (90°).

506272-01 Page 11 of 26Issue 0921
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,
cancausedamagebyfire and/oranexplosion,thatcould
result in personal injury or death.
WARNING
however, connecting it to the suction ports helps to
protect the manifold gauge set from damage caused
by high pressure.)
2. With both manifold valves closed, connect the cylinder
of R-410A refrigerant. Open the valve on the R-410A
cylinder(vapor only).
3. Open the high pressure side of the manifold to allow
R410Ainto the linesetand indoor unit. Weighin a trace
amount of R-410A. (A trace amount is a maximum of 2
oz.ofrefrigerant or 3 lbs. pressure.) Closethevalveon
theR-410A cylinder and thevalveon the high pressure
side of the manifold gauge set. Disconnect the R410A
cylinder.
4. Connectacylinder of nitrogenwithapressureregulating
valveto the centerportofthe manifold gaugeset. When
using high pressure gas such as nitrogen for this
purpose, be sure to use a regulator that can control
the pressure down to 1 or 2 psig.
5. Adjust nitrogen pressure to 150 psig. Open the valve
onthehigh side of themanifoldgaugeset to pressurize
the line set and the indoor coil.
6. After a short period of time, open a refrigerant port to
make sure that an adequate amount of refrigerant has
been added for detection (refrigerant requirements will
vary with lengths). Check all joints for leaks. Purge
nitrogen and R410A mixture. Correct any leaks and
recheck.
Usea thermocouple orthermistor electronic vacuumgauge
that is calibrated in microns. Use an instrument that reads
down to 50 microns.
1. Connectthemanifold gaugesettothe servicevalveports
as follows:
• Low pressure gauge to suction 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 vacuum pump.
5. Evacuate the line set and indoor unit to a minimum of 500
micronsorlower. Duringtheearlystagesofevacuation,itis
desirabletoclose the manifold gauge valve at leastonceto
determine if there is a rapid rise in pressure. Arapid rise in
pressure indicates a relatively large leak. If this occurs, the
leak testing procedure must be repeated.
6. When 500 microns or lower is maintained, close the
manifold gauge valves, turn off the vacuum pump, and
disconnectthemanifoldgauge center port hose fromthe
vacuum pump. Attach the manifold gauge center port
hose to a nitrogen cylinder with pressure regulator set to
150 psig and purge the hose. Open the manifold gauge
valvesto breakthevacuuminthe linesetandindoorunit.
Close the manifold gauge valves.
7. Shut off the nitrogen cylinder and remove the manifold
gaugehosefromthecylinder. Openthe manifold gauge
valvesto releasethenitrogenfromthe linesetandindoor
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 500 microns is maintained within a
20-minute period after shutting off the vacuum pump
and closing the manifold gauge valves.
9. When the requirements above have been met,
disconnect the manifold hose from the vacuum pump.
Open the service valves to break the vacuum in the line
set and indoor unit.
Evacuation
Evacuating the system of noncondensables is critical for
properoperation of the unit. Noncondensablesaredefined
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
refrigerantto produce substancesthat corrode copperpiping
and compressor parts.
Do not use a compressor to evacuate a system. Avoid
deep vacuum operation. Extremely low vacuums can
cause internal arcing and compressor failure. Danger
of equipment damage. Damage caused by deep
vacuum operation will void warranty.
WARNING

Page 12 of 26 506272-01Issue 0921
If the system is void of refrigerant, clean the system using
the procedure described below.
1. Use dry nitrogen to pressurize the system and check
for leaks. epair leaks, if possible.
2. Evacuatethesystem to remove as much of the moisture
as possible.
3. Use dry nitrogen to break the vacuum.
4. Evacuate the system again.
5. Weigh the appropriate amount of R-410A refrigerant
(listed on unit nameplate) into the system.
6. Monitorthesystemtodeterminetheamountofmoisture
remaining in the oil. Use a test kit to verify that the
moisture content is within the kit’s dry color range. It
maybe necessary to replace the filterdrierseveraltimes
to achieve the required dryness level. If system
dryness is not verified, the compressor will fail in
the future.
The outdoor unit should be charged during warm weather.
However,applications arise in which chargingmustoccurin
the colder months. The method of charging is determined
by the unit’s refrigerant metering device and the outdoor
ambient temperature.
Measuretheliquid line temperature and the outdoorambient
temperature as outlined below:
1. Connect the manifold gauge set to the service valve
ports as follows (see Figure 12):
START-UP
1. Rotate fan to check for frozen bearings or binding.
2. Inspect all factory and field-installed wiring for loose
connections.
3. Afterevacuation iscomplete,openliquidline andsuction
line service valves to release refrigerant charge
(contained in outdoor unit) into system.
4. Replace the stem caps and secure finger tight, then
tighten an additional 1/6 of a turn.
5. Check voltage supply at the disconnect switch. The
voltage must be within the range listed on the unit
nameplate. Ifnot,donotstartequipmentuntilthepower
companyhas beenconsulted and the voltagecondition
corrected.
6. Set thermostat for cooling demand, turn on power to
indoor blower and close the outdoor unit disconnect
switch to start the unit.
7. Recheck unit voltage with unit running. Power must be
within range shown on unit nameplate.
Refrigerant Charging
ThissystemischargedwithR-410Arefrigerantwhichoperates
at much higher pressures than R-22. The liquid line drier
providedwiththeunitisapprovedforusewithR-410A. Donot
replace it with one designed for use with R-22. This unit is
NOTapprovedfor usewithcoils whichusecapillary tubes
as a refrigerant metering device.
R-410A refrigerant cylinders are rose colored.
Refrigerant should be added through the vapor valve
in the liquid state.
Certain R-410A cylinders are identified as being
equipped with a dip tube. These allow liquid refrigerant
to be drawn from the bottom of the cylinder without
inverting the cylinder. Do not turn this type of cylinder
upside down to draw refrigerant.
Units are factory charged with the amount of R-410A
refrigerant indicated on the unit rating plate. This charge is
based on a matching indoor coil and outdoor coil with 15'
line set. For varying lengths of line set, refer to Table 5 for
refrigerant charge adjustment. A blank space is provided
on the unit rating plate to list the actual field charge.
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.
CAUTION
Mineral oils are not compatible with R-410A. If oil must
be added, it must be a polyolester oil.
IMPORTANT
Refrigerant Charge Adjustment
* If line length is greater than 15 ft., add this amount.
If line length is less than 15 ft., remove this amount.
Table 5
Liquid Line Set
Diameter
Oz. per 5 ft. adjust
from 15 ft. line set *
3/8 in. 3 oz. per 5 ft.

506272-01 Page 13 of 26Issue 0921
• Low pressure gauge to suction line service valve
• High pressure gauge to liquid line service valve
2. Close manifold gauge set valves. Connect the center
manifold hose to an upright cylinder of R-410A.
3. Ifroomtemperatureisbelow70°F,settheroomthermostat
to call for heat. This will create the necessary load for
properly charging the system in the cooling cycle.
4. Useadigitalthermometer to record the outdoor ambient
temperature.
5. When the heating demand has been satisfied, switch
the thermostat to cooling mode with a set point of 68°F.
When pressures have stabilized, use a digital
thermometer to record the liquid and suction line
temperatures.
6. Theoutdoortemperature will determinewhichcharging
method to use. Proceed with the appropriate charging
method.
Charge Using Weigh-In Method (Fixed Orifice/TXV
Systems)
If the system is void of refrigerant, or if the outdoor ambient
temperature is cool, first locate and repair any leaks then
use the weigh-in method to charge the unit.
1. Recover the refrigerant from the unit.
2. Conduct a leak check, then evacuate as previously
outlined.
3. Weighinthechargeaccording tothetotalamountshown
on the unit nameplate.
If weighing facilities are not available or if unit is being
charged during warm weather, follow one of the other
procedures outlined below.
Charge Using Subcooling Method (Fixed Orifice/TXV
Systems) – Outdoor Temperatures 65°F orAbove
If charging a fixed orifice or TXV system when the outdoor
ambient temperature is 65°F or above, the subcooling
method can be used to charge the unit.
1. With the manifold gauge hose on the liquid service port
and the unit operating stably, use a digital thermometer
to record the liquid line temperature.
2. At the same time, record the liquid line pressure reading.
3. Use the temperature/pressure chart (Table 6) to
determine the saturation temperature for the liquid line
pressure reading.
Figure 12
Use gauge ports on suction line valve and liquid line valve for evacuation refrigerant lines and indoor
coil. Use suction gauge to measure suction pressure during charging.
Cooling Cycle

Page 14 of 26 506272-01Issue 0921
ChargeUsingSuperheat Method(Fixed OrificeSystems)–
Outdoor Temperatures 65°F or above
1. With the manifold gauge hose on the suction service
port and the unit operating stably, use a digital
thermometer to record the suction line temperature.
2. At the same time, record the suction line pressure
reading.
3. Usethetemperature/pressurechart(Table6onpage13)to
determine the saturation temperature for the suction line
pressurereading.
4. Subtract the saturation temperature (according to the
chart) from the suction line temperature to determine
the superheat.
_____ ° Suction Line Temperature °F
_____ ° Saturation Temperature °F
_____ ° Superheat Value °F
–
=
4. Subtract the liquid line temperature from the saturation
temperature (according to the chart) to determine
subcooling.
5. Comparethesubcoolingvalue with thoseshowninTable
7. If subcooling is greater than shown, recover some
refrigerant. If subcooling is less than shown, add some
refrigerant.
_____ ° Saturation Temperature °F
_____ ° Liquid Line Temperature °F
_____ ° Subcooling Value °F
–
=
R410ATemperature/Pressure Chart
Table 6
.pmeT F°
e
russerP gisP
238.001
339.201
430.501
531.701
632.901
734.111
836.311
938.511
040.811
143.021
246.221
340.521
443.721
547.921
642.231
746.431
841.731
946.931
052.241
158.441
254.741
351.051
458.251
555.551
652.851
750.161
859.361
957.661
066.961
166.271
265.571
365.871
466.181
563.481
667.781
769.091
861.491
963.791
076.002
179.302
272.702
376.012
.pmeT F°
e
russerP gisP
470.412
574.712
679.022
774.422
870.822
976.132
083.532
180.932
287.242
385.642
483.052
581.452
680.852
780.262
880.662
980.072
091.472
192.872
293.282
395.682
498.092
591.592
694.992
798.303
892.803
997.213
0012.713
1018.123
2014.623
3010.133
4017.533
5015.043
6013.543
7011.053
8010.553
9010.063
0110.563
1110.073
2111.573
3112.083
4114.583
5117.093
.pmeT F°
e
russerP gisP
6110.693
7113.104
8117.604
9112.214
0217.714
1212.324
2218.824
3215.434
4212.044
5219.544
6218.154
7216.754
8215.364
9215.964
0316.574
1316.184
2318.784
3310.494
4312.005
5315.605
6319.215
7313.915
8318.525
9314.235
0410.935
1416.545
2413.255
3411.955
4419.565
5418.275
6418.975
7418.685
8418.395
9410.106
0511.806
1514.516
2517.226
3511.036
4515.736
5510.546
Subcooling Values for
Fixed Orifice or TXV Systems
Table 7
4SCU13 MODELS

506272-01 Page 15 of 26Issue 0921
Charge Using Approach Method (TXV Systems)
– Outdoor Temperatures 65°F or Above
The following procedure is intended as a general guide and
isforuseonexpansionvalvesystemsonly. For bestresults,
indoor temperature should 70°F to 80°F. 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 on
pressurechart on control boxcover. Minorvariations in
these pressures may be expected due to differences in
installations.Significant differences could mean that
thesystem is not properly charged or that aproblem
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.
5. Comparethe superheat value with those shown inTable
8. If superheat is greater than shown, add some
refrigerant. If superheat is less than shown, recover
some refrigerant.
_____ ° Liquid Line Temperature °F
_____ ° OutdoorAmbient Temperature °F
_____ ° Approach Temperature °F
–
=
6. Comparethe approach value withthoseshown inTable
9. If the values to do not agree with those provided in
Table 10, add refrigerant to lower the approach
temperature or recover refrigerant from the system to
increase the approach temperature.
Check Charge Using Normal Operating Pressures
Use Table 9 on page 16 to perform maintenance checks.
Table 9 is not a procedure for charging th system. Minor
variations in these pressures may be due to differences in
installations. Significant deviations could mean that he
systemis not properlycharged or that aproblem exists with
some component in the system.
4. Use the same digital thermometer to check liquid line
temperature.
5. Subtracttheoutdoorambienttemperaturefrom theliquid
linetemperaturetodeterminethe approachtemperature.
Table 8

Page 16 of 26 506272-01Issue 0921
Table 9
L - Liquid S - Suction
Values provided above are typical pressures. Indoor unit matchup, indoor air quality equipment, and indoor load will cause pressures to vary.
Table 10
Approach Values for TXV Systems
Approachvalueis the liquidlinetemperature minus theoutdoor
ambient temperature (±1°F).
NOTE: For best results, use the same digital thermometer to
check both outdoor ambient and liquid temperatures.
4SCU13 MODELS

506272-01 Page 17 of 26Issue 0921
OPERATION The control provides automatic switching from normal
heating operation to defrost mode and back. During the
compressorcycle (call fordefrost),the control accumulates
compressor run time at 30, 60, 90 minute field adjustable
intervals. If the defrost thermostat is closed when the
selected compressor run time inter ends, the defrost relay
is energized and the defrost begins.
Defrost Control Timing Pins
Each timing pin selection provides a different accumulated
compressorruntimeperiod during one thermostat run cycle.
Thistime period mustoccurbeforeadefrost cycle isinitiated.
The defrost interval can be adjusted to 30 (T1), 60 (T2), or
90 (T3) minutes. The defrost timing jumper is factory
installedto providea 60-minute defrostinterval. If thetiming
selector jumper is not in place, the control defaults to a 90-
minute defrost interval. The maximum defrost period is 14
minutes and cannot be adjusted.
Atest optionis provided for troubleshooting. Thetestmode
may be started any time the unit is in the heating mode and
the defrost thermostat is closed or jumpered. If the jumper
is in the TEST position at power-up, the control will ignore
the test pins. When the jumper is placed across the TEST
pins for 2 seconds, the control will enter the defrost mode.
Ifthejumperisremoved beforeanadditional5-secondperiod
has elapsed (7 seconds total), the unit will remain in defrost
passed. Ifthe jumper is not removeduntilafterthe additional
5-second period has elapsed, the defrost will terminate and
the test option will not functioin again until the jumper is
removed and reapplied.
Compressor Delay
The defrost board has a field-selectable function to reduce
occasionalsoundsthat may occur while theunit sicyclingin
and out of the defrost mode. The compresor will be cycled
offfor 30 seconds going in and out of the defrost mode when
the compressor delay jumper is removed.
NOTE: The30-second “OFF” cycle is not functinalwhen
jumpering the TEST pins.
Time Delay
The timed-off delay is 5 minutes long. The delay helps to
protectthecompressor from short cycling incasethepower
to the unit is interrupted or a pressure switch opens. The
delayis bypassedby placing the timerselect jumper across
the TEST pins fro 0.5 seconds.
Outdoor unit and indoor blower cycle on demand from the
room thermostat. When the thermostat blower switch is
moved to the ON position, the indoor blower operates
continuously.
Filter Drier
Theunit isequippedwith alargecampacitybi-flowfilter which
keepsthesystemcleanand dry. Ifreplacementisnecessary,
replacewith one of similardesigncapacity. Thereplacement
filter drier must be suitable for use with R-410Arefrigerant.
Crankcase Heater
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.
Emergency Heat Function (Room Thermostat)
An emergency heat function is designed into some room
thermostats. This feature is applicable when isolation of
outdoor unit is required or when auxiliary electric heat is
stage by outdoor thermostats. When the room thermostat
is placed in the emergency heat position, the outdoor unit
control circuit is isolated from power and the field-supplied
relaysbypassthe outdoorthermostats. Anamberindicating
light simultaneously comes on to remind the homeowner
that the unit is operating in the emergency heat mode.
Emergencyheat isusuallyusedduring anoutdoorshutdown,
butitshould also be used following apoweroutageif power
has been off for over an hour and the outdoor temperature
isbelow50°F. Systemshould be leftintheemergency heat
modeat least 6hourstoallowthe crankcase heatersufficient
time to prevent compressor slugging.
Defrost System
The defrost system includes two components: the defrost
thermostat and the defrost control.
Defrost Thermostat
The defrost thermostat is located on the liquid line between
the check/expansion valve and the distributor. When the
defrost thermostat senses 42° F or cooler, the thermostat
contactsclose and send a signal to thedefrost controlboard
to start the defrost timing. It also terminates defrost when
the liquid line warms up to 70° F.
Defrost Control
The defrost control board includes the combined functions
oftime/temperaturedefrostcontrol, defrost relay, diagnostic
LEDs and terminal strip for field wiring connections (see
Figure 3).

Page 18 of 26 506272-01Issue 0921
Pressure Switch Circuit
The defrost control includes two pressure switch circuits. A
high pressure switch is connected to the board’s HI-PS
terminals (see Figure 13 on page 17). The low pressure, or
loss-of-charge pressure, switch is connected to the LO-PS
terminals.
During a single demand cycle, the defrost control will lock
out the unit after the fifth time that the circuit is interrupted
byanypressureswtichwiredtothecontrol board. Inaddition,
thediagnosticLEDswillindicatealocked-outpressureswitch
after the fifthe occurrence of an open pressure switch (see
Table 11). The unit will remain locked out until power to the
boardis interrupted, then re-established,or untilthe jumper
is applied to the TEST pins for 0.5 seconds.
NOTE: Thedefrost control board ignores input from the
low pressure switch terminals as follows:
 During the TEST mode
 During the defrost cycle
 During the 90-second start-up period
For the first 90 seconds each time the reversing valve
switches heat/cool modes
If the TEST pins are jumpered and the 5-minute delay is
being bypassed, the LO-PS terminal signal is not
ignored during the 90-second start-up period.
Diganostic LEDs
ThedefrostboardusestwoLEDsfordiagnostics. TheLEDs
flash a specific sequence according to the condition as
shown in Table 11.
MAINTENANCE
Before performing maintenance operations on system,
turn the electric power to unit OFF at disconnect
switch(es). Unit may have multiple power supplies.
Electrical shock could cause personal injury or death.
WARNING
Before the start of each heating and cooling season, the
followingservicechecks should be performedbyaqualified
service technician.
Inspect and clean outdoor and indoor coils. The
outdoor coil may be flushed with a water hose.
NOTE: It may be necessary to flush the outdoor coil
morefrequently if it is exposed to substances which are
corrosive or which block airflow across the coil (such
as pet urine, cottonwood seeds, etc....).
Visually inspect the refrigerant lines and coils for leaks.
Check wiring for loose connections.
Check voltage at the indoor and outdoor units (with
units operating).
Check amperage draw at the outdoor fan motor,
compressor, and indoor blower motor. Values should
be compared with those given on unit nameplate.
Check, clean (or replace) indoor unit filters.
Check the refrigerant charge and gauge the system
pressures.
Check the condensate drain line for free and
unobstructed flow. Clean drain line, if necessary.
Adjust blower speed for cooling. Measure the pressure
drop over the coil to determine the correct blower CFM.
Belt drive blowers: Check drive belt for wwar and
proper tensions.
If insufficient cooling is reported, the unit should be gauged
andrefrigerantchargechecked(seeRefrigerant Charging
on page 12).
Mode Green LED Red LED
No Power
to Board
Normal Operation/
Power to Board
OFF OFF
Anti-Short Cycle
Lockout
Simultaneous Slow Flash
Low Pressure
Switch Fault
Low Pressure
Switch Lockout
High Pressure
Switch Fault
High Pressure
Switch Lockout
Alternating Slow Flash
OFF
OFF
OFF
OFF
Slow Flash
Slow Flash
ON
ON
Table 11
Defrost Control Board Diagnostic LEDs

506272-01 Page 19 of 26Issue 0921
HOMEOWNER INFORMATION
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.
Turn all electric power to unit OFF at disconnect
switch(es) before performing any maintenance
operations on system. Unit may have multiple power
supplies. Electrical shock could cause personal injury
or death.
WARNING
Ask your dealer to show you where the 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.
Disposable filters should be replaced with a filter of the
same type and size. If you are unsure of the filter you
need for your system, contact your dealer.
Manyindoor unitsareequippedwithreusablefoam filters.
These filters can be cleaned with a mild soap and water
solution. Rinsethefilter thoroughly and let dry completely
before returning to unit or grille.
The filter and all access panels must be in place any
time the unit is in operation.
Somesystems areequippedwithan electronicaircleaner,
designedtoremove the majority of airborne particlesfrom
the air passing through the cleaner. If your system
includes an electronic air cleaner, ask your dealer for
maintenance instructions.
Inspect and clean indoor indoor coil. The indoor
evaporator coil is equipped with a drain pan to collect
condensate formaed as the system removes humidity
fromtheinsideair. Haveyourdealershowyou thelocation
of the drain line and how to check for obstructions. This
also applies to an auxiliary drain, if one is installed.


Inspect and clean outdoor coil:
Make sure no obstructions restrict airflow to the outdoor
unit. Leaves,trash, or shrubscrowdingtheunitcancause
it to work harder and use more energy. Keep shrubbery
trimmed away from the unit and periodically check for
debris which collects around the unit.
Theoutdoorcoilmayrequirefrequentcleaning,depending
onenvironmentalconditions. Cleanthe outdoor coil with
an unpressurized water hose to remove surface
contaminants and debris. 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 (such as pet irome, cottonwood seeds,
etc...).
Heat Pump Operation
Heatpumpuntis have several characteristics youshouldbe
aware of:
Heat pumps satisfy heating demand by delivering large
amounts of warm air into the living space. This is quite
differentfromgas-fired, oil-fired, orelectricfurnaceswhich
deliver lower volumes of considerably hotter air to heat
the space.
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
45° F. An electronic control activates a defrost cycle
lasting 5 to 15 minutes at preset intervals to clear the
outdoor coil of the frost. Ashift in sound type does occur
during the defrost mode.
Duringthe defrost cycle, youmaynoticesteamrisingfrom
the unit. This is a normal occurrence. The thermostat
may engage auxiliary heat during the defrost cycle to
satisby a heating demand. The unit will return to normal
operation at the conclusion of the defrost cycle.
In case of extended power outage....
If the outdoor temperature is belwo 50° F and power to the
outdoor unit has been interrupted for 6 hours or longer,
observethe following whenrestoringpowertothe heatpump
system.
Setth eroomthermostatselectortothe“EmergencyHeat”
settingtoobtaintemporaryheatforaminimumof6hours.
This will allow system refrigerant pressures a nd
temperatures enough time to return to a stabilized
condition.
In the Emergency Heat mode, all heating demand is
satisfiedby auxiliary heat; heatpumpoperation is locked
out. After a 6-hour “warmup” period, the thermostat can
then be switched to the “Heat” setting and normal heat
operation may resume.

Page 20 of 26 506272-01Issue 0921
Thermostat Operation
Though your thermostat may vary somewhat from the
description below, its operation will be similar.
Temperature Setting Levers
Mostheat humpthermostatshavetwotemperatureselector
levers: one for heating and one for cooling. Set the levers
ordialstothedesiredtemperaturesetpointsfor both heating
andcooling. Avoidfrequent temperatureadjustment;turning
theunit offandbackonbefore pressuresequalizeputsstress
on unit compressor.
Fan Switch
In AUTO or INT (intermittent) mode, the blower operates
only when the thermostat calls for heating or cooling. This
modeisgenerallypreferred whenhumiditycontrolisapriority.
The ON or CONT mode provides continuous indoor blower
operation,regardlessofwhetherthecompressororauxiliary
heat are operating. This mode is required when constant
air circulation or filtering is desired.
System Switch
Setthesystemswitchforheating, cooling, or auto operation.
Theautomodeallowstheheatpumptoautomaticallyswitch
from heating mode to cooling mode to maintain
predetermined comfort settings. Many heat pump
thermostatsarealsoequippedwithan emergencyheatmode
whichlocks outheatpumpoperation andprovidestemporary
heat supplied by the auxiliary heat.
Indicating Light
Most heat pump thermostats have an amber light which
indicateswhentheheatpumpisoperatingintheemergency
heat mode.
Temperature Indicator
The temperature indicator displays the actual room
temperature.
Programmable Thermostats
Your system may be controlled by a programmable
thermostat. These thermostats provide the added feature
ofprogrammabletime-of-day setpoints for both heating and
cooling. Refer to the user’s information manual provided
with your particular thermostat for operation details.
Preservice Check
If your system fails to operate, check the following before
calling for service:
Check to see that all electrical disconnect switches are
ON.
Makesure the thermostattemperature selector isproperly
set.
Make sure the thermostat system switch is properly set.
Replace any blown fuses, or reset circuit breakers.
Make sure unit access panels are in place.
Make sure air filter is clean.
Locate unit model number and have it handy before
calling.