Carrier Base 50ZPA User manual

1
50ZPA
Single--Packaged Air Conditioner System
With R--22 Refrigerant
Single-- and Three--Phase Units (Sizes 024--060)
Installation Instructions
NOTE: Read the entire instruction manual before starting the
installation.
TABLE OF CONTENTS
Page
SAFETY CONSIDERATIONS 2........................
INTRODUCTION 2..................................
RECEIVING AND INSTALLATION 2--10................
Check Equipment 2.................................
Identify Unit 2...................................
Inspect Shipment 2................................
Provide Unit Support 2..............................
Slab Mount 2....................................
Ground Mount 2.................................
Provide Clearances 2................................
Place Unit 2.......................................
Select and Install Ductwork 2..........................
Configuring Units for Downflow (Vertical) Discharge 3...
Connect Condensate Drain 3..........................
Install Electrical Connections 5........................
High--Voltage Connections 5........................
Routing Power Leads Into Unit 6.....................
Connecting Ground Lead to Unit Ground 6.............
Routing Control Power Wires 6.....................
Accessory Electric Heat Wiring 6.....................
PRE--START--UP 7...................................
START--UP 7--17.....................................
Check for Refrigerant Leaks 7.........................
Start--Up Cooling and Make Adjustments 7...............
Checking Cooling and Heating Control Operation 7......
Refrigerant Charge 8..............................
No Charge 8.....................................
Low Charge Cooling 8.............................
Indoor Airflow and Airflow Adjustments 8.............
Unit Controls 9...................................
High--Pressure Relief Valve 9........................
Low--Pressure Switch 9............................
Compressor Overload 9............................
Compressor Rotation 9.............................
Sequence of Operation 9...........................
Fan Operation 9..................................
A05194
Fig. 1 -- Unit 50ZPA
Cooling Operation 9, 17............................
Heating Operation 17..............................
Continuous Fan 17................................
Defrost 17......................................
Electric Resistance Heating 17.......................
MAINTENANCE 17--20...............................
Air Filter 18.......................................
Unit Top Removal 18................................
Indoor Blower and Motor 18..........................
Outdoor Coil, Indoor Coil, and Condensate Drain Pan 19....
Outdoor Fan 19....................................
Electrical Controls and Wiring 19......................
Refrigerant Circuit 20................................
Indoor Airflow 20..................................
Metering Devices 20................................
Liquid Line Strainers 20..............................
High Flow Valves 20................................
TROUBLESHOOTING 20.............................
START--UP CHECKLIST 22...........................

2
SAFETY CONSIDERATIONS
Installation and servicing of this equipment can be hazardous due to
mechanical and electrical components. Only trained and qualified
personnel should install, repair, or service this equipment.
Untrained personnel can perform basic maintenance functions such
as cleaning and replacing air filters. All other operations must be
performed by trained service personnel. When working on this
equipment, observe precautions in the literature, on tags, and on
labels attached to or shipped with the unit and other safety
precautions that may apply.
Follow all safety codes. Installation must be in compliance with
local and national building codes. Wear safety glasses, protective
clothing, and work gloves. Have fire extinguisher available. Read
these instructions thoroughly and follow all warnings or cautions
included in literature and attached to the unit.
Recognize safety information. This is the safety--alert symbol .
When you seethis symbolon theunit and in instructions ormanuals,
be alert to the potential for personal injury. Understand these signal
words: DANGER, WARNING, and CAUTION. These words are
used with the safety--alert symbol. DANGER identifies the most se-
rious hazards which will result in severe personal injury or death.
WARNING signifies hazards which could result in personal injury
or death. CAUTION is used to identify unsafe practices which may
result in minor personal injury or product and property damage.
NOTE is used to highlight suggestions which will result in en-
hanced installation, reliability, or operation.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Before installing or servicing system, always turn off main
power to system. There may be more than one disconnect
switch. Turn off accessory heater power switch if applicable.
!
WARNING
INTRODUCTION
The 50ZPA packaged air conditioner is fully self--contained and
designed for outdoor installation (See Fig. 1). Standard units are
shipped in a horizontal--discharge configuration for installation on
a ground--level slab or directly on the ground if local codes permit.
Standard units can be converted to downflow (vertical) discharge
configurations for rooftop applications with a field supplied
plenum.
RECEIVING AND INSTALLATION
Step 1—Check Equipment
IDENTIFY UNIT
The unit model number and serial number are printed on the unit
informative plate. Check this information against shipping papers.
INSPECT SHIPMENT
Inspect for shipping damage while unit is still on shipping pallet. If
unit appearsto be damaged or is torn loose from its anchorage, have
it examined by transportation inspectors before removal. Forward
claim papers directly to transportation company. Manufacturer is
not responsible for any damage incurred in transit. Check all items
against shipping list. Immediately notify the nearest Carrier office
if any item is missing. To prevent loss or damage, leave all parts in
original packages until installation.
Step 2—Provide Unit Support
For hurricane tie downs, contact distributor for details and PE
(Professional Engineering) Certificate, if required.
SLAB MOUNT
Place the unit on a solid, level concrete pad that is a minimum of 4
in. thick with 2 in. above grade. The slab should extend
approximately 2 in. beyond the casing on all 4 sides of the unit. Do
not secure the unit to the slab except when required by local codes.
A 6--in. wide gravel apron should be used around the flat surface to
prevent airflow blockage by grass or shrubs. The unit should be
level wo within 1/4 in. This is necessary for the unit drain to function
properly.
GROUND MOUNT
The unit may be installed either on a slab or placed directly on the
ground iflocalcodes permit.Place theunit on level ground prepared
with gravel for condensate discharge.
Step 3—Provide Clearances
The required minimum service clearances are shown in Fig. 5.
Adequate ventilation and outdoor air must be provided.
The outdoor fan draws air through the outdoor coil and discharges
it through the top fan grille. Be sure that the fan discharge does not
recirculate to the outdoor coil. Do not locate the unit in either a
corner or under an overhead obstruction. The minimum clearance
under a partial overhang (such as a normal house overhang) is 48 in.
above the unit top. The maximum horizontal extension of a partial
overhang must not exceed 48 in.
IMPORTANT: Do not restrict outdoor airflow. An air restriction at
either the outdoor--air inlet or the fan discharge may be detrimental
to compressor life.
Do not place the unit where water, ice, or snow from an overhang
or roof will damage or flood the unit. Do not install the unit on
carpeting or other combustible materials. Slab--mounted units
should be at least 4 in. above the highest expected water and runoff
levels. Do not use unit if it has been under water.
Step 4—Place Unit
Unit can be moved with the rigging holds provided in the unit base.
Refer to Table 1 for operating weights. Use extreme caution to
prevent damage when moving the unit. Unit must remain in an
upright position during all moving operations. The unit must be
level with in 1/4 in. for proper condensate drainage; the
ground--level pad must be level before setting the unit in place.
When a field--fabricated support is used, be sure that the support is
level and that it properly supports the unit.
Step 5—Select and Install Ductwork
The design and installation of the duct system must be in accordance
with the standards of the NFPA for installation of non--residence
type air conditioning and ventilating systems, NFPA 90A or
residence type, NFPA 90B and/or local codes and ordinances.
Select and size ductwork, supply--air registers, and return air grilles
according to ASHRAE (American Society of Heating,
Refrigeration, and Air Conditioning Engineers) recommendations.
Use the duct flanges provided on the supply-- and return--air
openings on the side of the unit. See Fig. 5 for connection sizes and
locations. The 14--in. round duct collars are shipped inside the unit
attached to the base pan in theindoor blowercompartment. They are
field--installed and must be removed from the indoor blower
compartment prior to start--up, even if they are not used for
installation.
50ZPA

3
When designing and installing ductwork, consider the following:
UNIT DAMAGE HAZARD
Failure to follow this caution may result in damage to unit
components.
When connecting ductwork to units, do not drill deeper than
3/4 inch in shaded area shown in Fig. 2 or coil may be
damaged.
CAUTION
!
1. All units should havefield--supplied filters or accessory filter
rack installed in the return--air side of the unit.
Recommended sizes for filters are shown in Table 1.
2. Avoid abrupt duct size increases and reductions. Abrupt
change in duct size adversely affects air performance.
IMPORTANT: Use flexible connectors between ductwork and
unit to prevent transmission of vibration. Use suitable gaskets to
ensure weather tight and airtight seal. When electric heat is installed,
use fireproof canvas (or similar heat resistant material) connector
between ductwork and unit discharge connection. If flexible duct is
used, insert a sheet metal sleeve inside duct. Heat resistant duct
connector (or sheet metal sleeve) must extend 24--in. from electric
heater element.
3. Size ductwork for cooling air quantity (cfm). The minimum
air quantity for proper electric heater operation is listed in
Table 2. Heater limit switches may trip at air quantities below
those recommended.
4. Seal, insulate, and weatherproof all external ductwork. Seal,
insulate and cover with a vapor barrier all ductwork passing
through conditioned spaces. Follow latest Sheet Metal and
Air Conditioning Contractors National Association
(SMACNA) and Air Conditioning Contractors Association
(ACCA) minimum installation standards for residential
heating and air conditioning systems.
5. Secure all ducts to building structure. Flash, weatherproof,
and vibration--isolate duct openings in wall or roof
according to good construction practices.
Figure 4 shows a typical duct system with 50ZPA unit installed.
19.17 3.92
A05195
Fig. 2 -- Area Not to be Drilled More Than 3/4--in.
CONFIGURING UNITS FOR DOWNFLOW (VERTICAL)
DISCHARGE
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Before performing service or maintenance operations on the
system, turn off main power to unit and install lockout tag.
!
WARNING
Units are dedicated side supply products. They are not convertible
to vertical air supply. A field--supplied plenum must be used to
convert to vertical air discharge.
Step 6—Connect Condensate Drain
NOTE: When installing condensate drain connection be sure to
comply with local codes and restrictions.
Unit removes condensate through a 1--3/64--in. ID hole (using
3/4--in. OD piping or tubing) which is located at the end of the unit.
See Fig. 5 for location of condensate connection.
Condensate water can be drained directly onto the roof in rooftop
installations (where permitted) or onto a gravel apron in ground
level installations. Install a field--supplied condensate trap at end of
condensate connection to ensure proper drainage. Make sure that
the outlet of the trap is at least 1 in. lower than the drain pan
condensate connection to prevent the pan from overflowing (See
Fig. 3 and 4). When using a gravel apron, make sure it slopes away
from the unit.
If the installation requires draining the condensatewater away from
the unit, install a 2--in. trap using a 3/4--in. OD tubing or pipe. (See
Fig. 3 and 4.) Make sure that the outlet of the trap is at least 1 in.
lower than the unit drain--pan condensate connection to prevent the
pan from overflowing. Prime the trap with water. Connect a drain
tube using a minimum of 3/4--in. PVC, 3/4--in. CPVC, or 3/4--in.
copper pipe (all field supplied). Do not undersize thetube. Pitch the
drain tube downward at a slope of at least 1 in. for every 10 ft of
horizontal run. Be sure to check the drain tube for leaks. Prime trap
at the beginning of the cooling season start--up. Allowable glues for
condensate trap connection are: Standard ABS, CPVC, or PVC
cement..
1” (25mm) MIN.
2” (50mm) MIN.
TRAP
OUTLET
C99013
Fig. 3 -- Condensate Trap
TRAP
OUTLET
2" min.
1" min.
C00009
Fig. 4 -- PVC Condensate Trap
50ZPA

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A05201
UNIT ELECTRICAL
CHARACTERISTICS
UNIT WEIGHT UNIT HEIGHT
IN. [MM]
CENTER OF GRAVITY
IN. [MM]
lb kg A X Y Z
50ZPA024 208/230--1--60 293 133 30.13 [765] 14.0 [356] 19.0 [483] 15.0 [381]
50ZPA030 208/230--1--60, 208/230--3--60 324 147 34.13 [867] 14.0 [356] 19.0 [483] 16.0 [406]
50ZPA036 208/230--1--60, 208/230--3--60 377 171 42.13 [1070] 14.0 [356] 19.0 [483] 19.8 [503]
50ZPA042 208/230--1--60, 208/230--3--60 389 177 42.13 [1070] 14.0 [356] 19.0 [483] 21.9 [556]
50ZPA048 208/230--1--60, 208/230--3--60 384 175 42.13 [1070] 14.0 [356] 19.0 [483] 19.8 [503]
50ZPA060 208/230--1--60, 208/230--3--60 433 197 42.13 [1070] 14.0 [356] 19.0 [483] 21.9 [556]
Fig. 5 -- Unit Base Dimensions, 50ZPA024--060
TOP COVER
INDOOR
THERMOSTAT
DISCONNECT
PER NEC*
(UNIT AND
ELECTRIC
HEATER)
FROM
POWER
SOURCE
RETURN
AIR
POWER AND
LOW-VOLTAGE
ENTRY
COMPOSITE
RUST-PROOF
BASEPAN
CONDENSATE
DRAIN
CONNECTION
*Separate disconnect per NEC
(National Electrical Code) required
for electric heater when single-
point connection is not used.
Power Wiring
Control Wiring
Condenser Airflow
Evaporator Airflow
C00008
Fig. 6 -- Typical Installation
50ZPA

5
Table 1—Physical Data
UNIT SIZE 024 030 036 042 048 060
NOMINAL CAPACITY (ton) 22--1/2 33--1/2 4 5
OPERATING WEIGHT (lb.) 268 299 352 364 359 408
COMPRESSOR Scroll UltraTechScroll
REFRIGERANT (R--22)
Quantity (lb.) 6.8 9.5 9.5 11.1 10.7 12.5
REFRIGERANT METERING DEVICE AccuRater®TXV
Orifice ID (in.) 0.067 0.067 0.082 0.086 – –
Orifice OD (in.) 0.049 0.057 0.059 0.063 0.070 0.073
CONDENSER COIL Copper Tubes, Aluminum Plate Fins
Rows…Fins/in. 2…21 2…21 2…21 2…21 2…21 2…21
Face Area (sq. ft.) 11.1 12.7 15.8 15.8 13.3 15.8
CONDENSER FAN Propeller
Nominal Cfm 2600 2600 3200 3200 3200 3300
Diameter 20 20 20 20 20 20
Motor HP (RPM) 1/8 (825) 1/8 (825) 1/4 (1100) 1/4 (1100) 1/4 (1100) 1/2 (1100)
EVAPORATOR COIL Copper Tubes, Aluminum Plate Fins
Rows…Fins/in. 3…17 3…17 4…17 4…17 4…17 4…17
Face Area (sq. ft.) 4.3 4.9 4.9 6.1 4.9 6.1
Evaporator blower Direct Drive
Nominal Airflow (Cfm) 800 1000 1200 1400 1600 1875
Size (in.) 10x8 10x8 11x9 11x9 11x10 11x10
Motor HP (RPM) 1/2 (1050) 1/2 (1050) 3/4 (1050) 3/4 (1050) 1 (1050) 1 (1050)
CONNECTING DUCT SIZES Round
Supply Air (in.) 14
Return Air (in.) 14
Return--Air Filters (in.)* Throwaway 24 x 24 24 x 24 24 x 24 24 x 30 30 x 30 30 x 30
*Required filter sizes shown are based on the ARI (Air conditioning & Refrigeration Institute) rated airflow at a velocity of 300 ft/min for throwaway type or 450
ft/min for high capacity type. Recommended filters are 1 ---in. thick.
Table 2—Minimum Airflow for Safe
Electric Heater Operation
Unit Size Minimum Airflow (CFM)
5kW 7.5kW 10kW 15kW 20kW
024 400 550 650
030 450 600 800 850
036 450 600 800 850 900
042 450 600 800 850 900
048 450 600 800 850 900
060 450 600 800 850 900
Step 7—Install Electrical Connections
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
The unit cabinet must have an uninterrupted, unbroken
electricalground to minimizethe possibility of personal injury
if an electrical fault should occur. This ground may consist of
an electrical wire connected to the unit ground screw in the
control compartment, or conduit approved for electrical
ground when installed in accordance with NEC, ANSI/NFPA
American National Standards Institute/National Fire
Protection Association (latest edition) (in Canada, Canadian
Electrical Code CSA C22.1) and local electrical codes.
!
WARNING
UNIT COMPONENT DAMAGE HAZARD
Failure to follow this caution may result in damage to the unit
being installed.
1. Make all electrical connections in accordance with NEC
ANSI/NFPA (latest edition) and local electrical codes
governing such wiring. In Canada, all electrical
connections must be in accordance with CSA standard
C22.1 Canadian Electrical Code Part 1 and applicable local
codes. Refer to unit wiring diagram.
2. Use only copper conductor for connections between
field--supplied electrical disconnect switch and unit. DO
NOT USE ALUMINUM WIRE.
3. Be sure that high--voltage power to unit is within operating
voltage range indicated on unit rating plate. On 3--phase
units, ensure phases are balanced within 2 percent. Consult
local power company for correction of improper voltage
and/or phase imbalance.
4. Do not damageinternal componentswhen drilling through
any panel to mount electrical hardware, conduit, etc.
!
CAUTION
HIGH--VOLTAGE CONNECTIONS
The unit must have a separate electrical service with a
field--supplied, waterproof disconnect switch mounted at, or within
sight from the unit. Refer to the unit rating plate, NEC and local
codes for maximum fuse/circuit breaker size and minimum circuit
amps (ampacity) for wire sizing (See Table 5 for electrical data).
The field--supplied disconnect may be mounted on the unit over the
high--voltage inlet hole when the standard power and low--voltage
entry points are used. See Fig. 6 and 7 for acceptable location.
50ZPA

6
Operation of unit on improper line voltage constitutes abuse and
may cause unit damage that could affect warranty.
ROUTING POWER LEADS INTO UNIT
Use only copper wire between disconnect and unit. The
high--voltage leads should be in a conduit until they enter the unit;
conduit termination at the unit must be watertight. Run the
high--voltage leads through the hole on the control box side of the
unit (See Fig. 7). When the leads are inside the unit, run leads to the
control box (SeeFig. 8).For single--phaseunits, connectleads tothe
black and yellow wires (See Fig. 9).
CONNECTING GROUND LEAD TO UNIT GROUND
Connect the ground lead to the chassis using the unit ground in the
control box (See Fig. 8 and 9).
ROUTING CONTROL POWER WIRES (24--V)
Form a drip--loop with thethermostatleads beforerouting them into
the unit. Route the thermostat leads through grommeted hole
provided in unit into unit control box (See Fig. 7). Connect
thermostatleads and unit power leads asshown in Fig. 9, 10 and 11.
Route thermostat wires through grommet providing a drip--loop at
the panel. Connect low--voltage leads to the thermostat as shown in
Fig. 10 & 11.
The unit transformer supplies 24--v power for complete system
including accessory electrical heater. Transformer is factory wired
for 230--v operation.
ACCESSORY ELECTRIC HEAT WIRING
Refer to accessory electric heat installation instructions for
information on installing accessory electric heat. Accessory electric
heat wiring is shown in Fig. 12, 13, 14 and 15.
HIGH-VOLTAGE POWER
WIRING ENTRY HOLE
LOW-VOLTAGE WIRING
ENTRY HOLE
A05198
Fig. 7 -- Unit Electrical Connection
HEATER LOW
VOLTAGE PLUG
A05388
Fig. 8 -- Control Box Wiring
3-PHASE
CONNECTIONS
TO DISCONNECT
PER NEC
SINGLE-PHASE
CONNECTIONS
TO DISCONNECT
PER NEC
GROUND
LEAD
UNIT GROUND
BLK
YEL
BLU
L
L
L
C00012
Fig. 9 -- Line Power Connections
Unit Control
Power
Thermostat
and subbase
G
Y
W2
W3
R
RED
GRN
YEL
C
BRN
WHT
VIO
A05213
Fig. 10 -- Control Connections (Sizes 024--042)
50ZPA

7
Unit Control
Power
Thermostat
and subbase
G
Y1
Y2
W2
R
RED
GRN
YEL
W3
PNK
BRN
C
WHT
VIO
A05214
Fig. 11 -- Control Connections (Sizes 048--060)
PRE--START--UP
FIRE, EXPLOSION, ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death and/or property damage.
1. Follow recognized safety practices and wear protective
goggles when checking or servicing refrigerant system.
2. Relieve and recover all refrigerant from system before
touching or disturbing anything inside terminal box if
refrigerant leak is suspected around compressor terminals.
3. Never attempt to repair soldered connection while
refrigerant system is under pressure.
4. Do not use torch to remove any component. System
contains oil and refrigerant under pressure.
5. To remove a component, wear protective goggles and
proceed as follows:
a. Shut off electrical power to unit and install lockout
tag.
b. Relieve and reclaim all refrigerant from system
using both high-- and low--pressure ports.
c. Cut component connecting tubing with tubing
cutter and remove component from unit.
d. Carefully unsweat remaining tubing stubs when
necessary. Oil can ignite when exposed to flame.
!
WARNING
Proceed as follows to inspect and prepare the unit for initial start--up:
1. Remove all access panels.
2. Read and follow instructions on all DANGER, WARNING,
CAUTION, and INFORMATION labels attached to, or
shipped with unit.
3. Make the following inspections:
a. Inspect for shipping and handling damages, such as
broken lines, loose parts, disconnected wires, etc.
b. Inspect for oil at all refrigerant tubing connections and on
unit base. Detecting oil generally indicates a refrigerant
leak. Leak test all refrigerant tubing connections using
electronic leak detector, or liquid--soap solution. If a
refrigerant leak is detected, see Check for Refrigerant
Leaks section.
c. Inspect all field-- and factory--wiring connections. Be
sure that connections are completed and tight.
d. Ensure wires do not touch refrigerant tubing or sharp
sheet metal edges.
e. Inspect coil fins. If damaged during shipping and
handling, carefully straighten fins with a fin comb.
4. Verify the following conditions:
a. Make sure that outdoor--fan blade is correctly positioned
in fan orifice. Top edge of bladeshould be3.125 in.down
from outdoor coil outlet grille (size 024--048, See Fig.19)
or hub should be 0.708--in. away from motor end bell
(size 060, See Fig. 20). See Outdoor Fan Adjustment
section.
b. Make sure that air filter is in place.
c. Make sure that condensate drain pan and trap are filled
with water to ensure proper drainage.
d. Make sure that all tools and miscellaneous loose parts
have been removed.
START--UP
Step 1—Check for Refrigerant Leaks
Proceed as follows to locate and repair a refrigerant leak and to
charge the unit:
1. Locate leak and make sure that refrigerant system pressure
has been relieved and reclaimed from both high-- and
low--pressure ports.
2. Repair leak following accepted practices.
NOTE: Install a filter drier whenever the system has been opened
for repair.
Step 2—Start--Up Cooling and Make Adjustments
Complete the required procedures given in the Pre--Start--Up
section before starting the unit. Do not jumper any safety devices
when operating the unit. Do not operate the unit in cooling mode
when the outdoor temperature is below 40°F (unless accessory
low--ambient kit is installed). Do not rapid cycle the compressor.
Allow 5 min. between “on” cycles to prevent compressor damage.
CHECKING COOLING AND HEATING CONTROL
OPERATION
Start and check the unit for proper cooling control operation as
follows:
1. Place room thermostat SYSTEM switch in OFF position.
Observe that blower motor starts when FAN switch is placed
in ON position and shuts down within 60 sec. (for 024--042)
or 90 seconds (for 048 and 060) when FAN switch is placed
in AUTO position.
2. Place SYSTEM switch in COOL position and FAN switch
in AUTO position. Set control below room temperature.
Observe that compressor, outdoor fan, and indoor blower
motors start and that reversing valve shifts. Observe that
cooling cycle shuts down when control setting is satisfied.
Reversing valve (RV) remains energized.
3. Place system switch in HEAT position. Observe that
compressor, indoor fan and outdoor fan energize (Reversing
Valve is deenergized in air conditioner heating mode). Set
control above room temperature. Observe that heating cycle
shuts down when control setting is satisfied.
4. When using an automatic changeover room thermostat,
place both SYSTEM and FAN switches in AUTO positions.
Observe that unit operates in Cooling mode when
temperature control is set to call for Cooling (below room
temperature), and unit operates in Heating mode when
temperature control is set to call for Heating (above room
temperature).
50ZPA

8
Table 3—Required Subcooling
REQUIRED SUBCOOLING °F(°C)
Model Size Outdoor Ambient Temperature
75 (24) 82 (28) 85 (29) 95 (35) 105 (41)
048 17.5 (9.7) 17 (9.4) 16.5 (9.2) 16 (8.9) 14 (7.8)
060 21 (11.7) 20.5 (11.4) 20 (11.1) 19 (10.6) 16 (8.9)
Table 4—Required Liquid Line Temperature
REQUIRED LIQUID LINE TEMPERATURE FOR A SPECIFIC SUBCOOLING (R--22)
Pressure (kPa) Required Subcooling (°F) Pressure (kPa) Required Subcooling (°F)
510 15 20 3 6 8 11
134 71 66 61 56 924 24 22 19 16
141 74 69 64 59 972 26 23 21 18
156 80 75 70 65 1075 30 27 24 21
163 83 78 73 68 1124 31 28 26 23
170 86 81 76 71 1172 33 30 27 24
177 89 84 79 74 1220 34 31 29 26
184 91 86 81 76 1268 36 33 30 27
191 94 89 84 79 1317 37 34 31 29
198 96 91 86 81 1365 38 36 33 30
205 98 93 88 83 1413 40 37 34 31
213 101 96 91 86 1468 41 38 36 33
221 104 99 94 89 1524 43 40 37 34
229 106 101 96 91 1579 44 41 38 36
237 108 103 98 93 1634 45 42 40 37
245 111 106 101 96 1689 47 44 41 38
253 113 108 103 98 1744 48 45 42 40
262 116 111 106 101 1806 49 46 44 41
271 118 113 108 103 1868 51 48 45 42
280 121 116 111 106 1930 52 49 46 44
289 123 118 113 108 1992 53 51 48 45
298 125 120 115 110 2054 55 52 49 46
307 128 123 118 113 2116 56 53 50 48
317 130 125 120 115 2185 57 54 52 49
327 132 127 122 117 2254 59 56 53 50
337 135 130 125 120 2323 60 57 54 52
347 137 132 127 122 2392 61 58 56 53
357 139 134 129 124 2461 62 60 57 54
367 142 137 132 127 2530 64 61 58 55
280 121 116 111 106 1930 52 49 46 44
289 123 118 113 108 1992 53 51 48 45
298 125 120 115 110 2054 55 52 49 46
307 128 123 118 113 2116 56 53 50 48
317 130 125 120 115 2185 57 54 52 49
327 132 127 122 117 2254 59 56 53 50
337 135 130 125 120 2323 60 57 54 52
347 137 132 127 122 2392 61 58 56 53
357 139 134 129 124 2461 62 60 57 54
367 142 137 132 127 2530 64 61 58 55
Step 3—Refrigerant Charge
Refrigerant Charge — Amount of refrigerant charge is listed on unit
nameplate and in Table 1. Refer to Carrier Refrigerant Service
Techniques Manual, Refrigerants section. Unit panels must be in
place when unit is operating during charging procedure. Unit must
operate a minimum of 15 minutes before checking charge.
NO CHARGE
Refer to Carrier Refrigerant Service Techniques. Use standard
evacuating techniques. After evacuating system, weigh in the
specified amount of refrigerant (refer to Table 1).
LOW CHARGE COOLING
024--042 units:
1. Measure suction line pressure by attaching a gauge to the
service port.
2. Measure the suction line temperature by attaching a
temperature sensing device to it.
3. Insulate the temperature sensing device so that the outdoor
ambient doesn’t affect the reading.
4. Locate the measured suction line pressure in the top row of
Table 7 and the measured outdoor ambient temperature in
the left column of the table. Based on the two values,
determine the required suction line temperature.
5. If the measured suction line temperature is greater than the
tabulated temperature, add charge in the system.
048 and 060 units:
1. Measure discharge line pressure by attaching a gauge to the
service port.
2. Measure the liquid line temperature by attaching a
temperature sensing device to it.
50ZPA

9
3. Insulate the temperature sensing device so that the outdoor
ambient doesn’t affect the reading.
4. Refer to the required subcooling in Tables 3 and 4 to find the
required subcooling based on themodelsizeand theoutdoor
ambient temperature.
5. Interpolate if the outdoor temperature lies in between the
table values. Extrapolate if the temperature lies beyond the
table range.
6. Find the pressure value corresponding to the measured
pressure on the compressor discharge line.
7. Read across from the pressure reading to obtain the Liquid
line temperature for a required subcooling.
8. Add charge if the measured temperature is higher than the
liquid line temperature value in the table.
9. Add charge using the service connection on the suction line
of the compressor.
Step 4—Indoor Airflow and Airflow Adjustments
NOTE: For cooling operation, the recommended airflow is 350 to
450 cfm for each 12,000 Btuh of rated cooling capacity.
Table 6 shows dry coil air delivery for horizontal discharge units.
Tables 9--10 show pressure drops.
NOTE: Be sure that all supply-- and return--air grilles are open, free
from obstructions, and adjusted properly.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Disconnect electrical power to the unit and install lockout tag
before changing blower speed.
!
WARNING
Airflow can be changed by changing the lead connections of the
blower motor.
All 50ZPA blower motors are factory wired for rated airflow
operation.
FOR 208/230V BLOWER MOTORS
The motor lead speed connections are as follows:
SIZE RATED AIRFLOW HIGH AIRFLOW
024 Tap 1 Tap 3
030 Tap 2 Tap 4
036 Tap 1 Tap 3
042 Tap 2 Tap 4
SIZE
RATED AIRFLOW HIGH AIRFLOW
Low
Stage
High
Stage
Low
Stage
High
Stage
048 Tap 1 Tap 3 Ta p 2 Tap 4
060 Tap 1 Tap 3 Ta p 2 Tap 4
Step 5—Unit Controls
All compressors have the following internal--protection controls.
HIGH--PRESSURE RELIEF VALVE
This valve opens when the pressure differential between the low and
high side becomes excessive.
LOW--PRESSURE SWITCH
Located on the outdoor liquid line is a low--pressure switch which
functions as a loss--of--charge switch. This switch contains a
Schrader core depressor. This switch opens at 7 psig and closes at 22
psig. No adjustment is necessary.
COMPRESSOR OVERLOAD
This overload interrupts power to the compressor when either the
current or internal temperature become excessive, and
automatically resets when the internal temperature drops to a safe
level.
This overload may require up to 60 minutes (or longer) to reset;
therefore, if the internal overload is suspected of being open,
disconnect the electrical power to the unit and check the circuit
through the overload with an ohmmeter or continuity tester.
COMPRESSOR ROTATION
On 3--Phase units it is important to be certain compressor is rotating
in the proper direction. To determine whether or not compressor is
rotating in the proper direction:
1. Connect service gages to suction and discharge pressure
fittings.
2. Energize the compressor.
3. The suction pressure should drop and the dischargepressure
should rise, as is normal on any start--up.
If the suction pressure does not drop and thedischarge pressuredoes
not rise to normal levels:
1. Turn off power to the unit and tag disconnect.
2. Reverse any two of the unit power leads.
3. Turn on power to the unit.
The suction and dischargepressure levels should now move to their
normal start--up levels.
NOTE: When the compressor is rotation in the wrong direction,the
unit makes an elevated level of noise and does not provide cooling.
Step 6—Sequence of Operation
FAN OPERATION
The FAN switch on the thermostat controls indoor fan operation.
When the FAN switch is placed in the ON position, the IFR
(indoor--fan relay) is energized through the G terminal on the
thermostat. The normally--open contacts close, which then provide
power to the indoor (evaporator)fan motor(IFM). TheIFM willrun
continuously when the FAN switch is set to ON.
When the FAN switch is set to AUTO, the thermostat deenergizes
the IFR (provided there is not a call for cooling). The contacts open
and the IFM is deenergized. The IFM will be energized only when
there is a call for cooling, in air conditioner heating mode or if the
unit is equipped with accessory electric heat, the indoor--fan motor
will also run while the accessory electric heat is energized.
NOTE: Some units are equipped with a time--delay relay. On these
units, the indoor fan remains on for 30 seconds after G or Y is
deenergized.
COOLING OPERATION (SIZES 024--042)
With acallforcooling (Y/Y2), the indoor fan energizesimmediately
whereas the contactor energizes after a 5 minute time delay (in case
of initial start--up) starting the compressor and the outdoor fan
motor. When the cooling demand is met, Y/Y2 de--energizes,
shutting the compressor, indoor fan and the outdoor fan.
50ZPA

10
A06406
Fig. 12 -- Typical Single--Phase Unit Electrical Diagram (Sizes 024--042)
50ZPA

11
A06407
Fig. 13 -- Typical Single--Phase Unit Electrical Diagram (Sizes 048--060)
50ZPA

12
A06336
Fig. 14 -- Typical Three--Phase Unit Electrical Diagram (Sizes 030--042)
50ZPA

13
A06337
Fig. 15 -- Typical Three--Phase Unit Electrical Diagram (Sizes 048--060)
50ZPA

14
A05209
Fig. 16 -- Single--Phase Accessory Electric Heater Wiring
A06327
Fig. 17 -- Three--Phase Accessory Electric Heater Wiring
50ZPA

15
Table 5—Electrical Data--50ZPA
UNIT
SIZE
NOMINAL
VOLTAGE
( V --- P h --- H z )
VOLTAGE
RANGE COMPRESSOR OFM IFM ELECTRIC HEAT POWER SUPPLY
Min Max RLA LRA FLA FLA Nominal
kW FLA MCA MOCP
024 208/230--- 1---60 187 253 10.9 54.0 0.9 4.1
--- / --- --- / --- 18.6/18.6 25/25
3.8/5 18.1/20.8 41.2/44.7 45/50
7.5/10 36.1/41.7 63.8/70.7 60/70
5.4/7.2 26/30 51.1/56.1 50/50
030 208/230--- 1---60 187 253 13.5 72.5 0.9 4.1
--- / --- --- / --- 21.8/21.8 30/30
3.8/5 18.1/20.8 44.4/47.9 50/50
7.5/10 36.1/41.7 67.0/73.9 70/70
11.3/15 54.2/62.5 89.5/100.0 90/100
5.4/7.2 26/30 54.3/59.3 60/60
030 208/230--- 3---60 187 253 9.0 63.0 0.9 4.1
--- / --- --- / --- 16.3/16.3 20/20
3.8/5 10.4/12 29.3/31.3 35/35
7.5/10 20.8/24.1 42.3/46.3 45/45
7.5/10 20.8/24.1 42.3/46.3 45/45
11.3/15 31.3/36.1 55.3/61.4 50/70
036 208/230--- 1---60 187 253 17.5 88.0 1.5 6.0
--- / --- --- / --- 29.4/29.4 35/35
3.8/5 18.1/20.8 52.0/55.4 60/60
7.5/10 36.1/41.7 74.5/81.5 80/80
11.3/15 54.2/62.5 97.1/107.5 100/100
5.4/7.2 26/30 61.9/66.9 70/70
036 208/230--- 3---60 187 253 10.7 77.0 1.5 6.0
--- / --- --- / --- 20.9/20.9 25/25
3.8/5 10.4/12 33.9/35.9 40/40
7.5/10 20.8/24.1 46.9/50.9 50/50
7.5/10 20.8/24.1 46.9/50.9 50/50
11.3/15 31.3/36.1 59.9/66.0 60/60
15/20 41.7/48.1 73.0/81.0 70/90
042 208/230--- 1---60 187 253 19.4 104.0 1.5 6.0
--- / --- --- / --- 31.7/31.7 40/40
3.8/5 18.1/20.8 54.3/57.8 60/70
7.5/10 36.1/41.7 76.9/83.8 80/90
11.3/15 54.2/62.5 99.4/109.9 100/110
15/20 72.2/83.3 122.0/135.9 110/150
5.4/7.2 26/30 64.2/69.2 70/80
042 208/230--- 3---60 187 253 11.4 88.0 1.5 6.0
--- / --- --- / --- 21.7/21.7 25/25
3.8/5 10.4/12 34.8/36.8 40/45
7.5/10 20.8/24.1 47.8/51.8 50/50
7.5/10 20.8/24.1 47.8/51.8 50/50
11.3/15 31.3/36.1 60.8/66.8 60/60
15/20 41.7/48.1 73.8/81.9 70/90
048 208/230--- 1---60 187 253 24.7 116.0 1.5 7.7
--- / --- --- / --- 40.0/40.0 50/50
3.8/5 18.1/20.8 62.6/66.1 80/80
7.5/10 36.1/41.7 85.1/92.1 100/100
11.3/15 54.2/62.5 107.7/118.1 110/125
15/20 72.2/83.3 130.3/144.2 125/125
5.4/7.2 26/30 72.5/77.5 90/90
048 208/230--- 3---60 187 253 12.8 91.0 1.5 7.7
--- / --- --- / --- 25.2/25.2 30/30
3.8/5 10.4/12 38.3/40.3 45/50
7.5/10 20.8/24.1 51.3/55.3 50/60
7.5/10 20.8/24.1 51.3/55.3 50/60
11.3/15 31.3/36.1 64.3/70.3 60/70
15/20 41.7/48.1 77.3/85.4 70/80
060 208/230--- 1---60 187 253 28.0 118.0 3.0 7.7
--- / --- --- / --- 45.7/45.7 60/60
3.8/5 18.1/20.8 68.2/71.7 90/90
7.5/10 36.1/41.7 90.8/97.8 100/110
11.3/15 54.2/62.5 113.4/123.8 125/125
060 208/230--- 3---60 187 253 18.5 123.0 3.0 7.7
--- / --- --- / --- 33.9/33.9 40/40
3.8/5 10.4/12 46.9/48.9 60/60
7.5/10 20.8/24.1 59.9/64.0 70/70
7.5/10 20.8/24.1 59.9/64.0 70/70
11.3/15 31.3/36.1 73.0/79.0 80/80
15/20 41.7/48.1 86.0/94.0 90/100
See Legend on following page.
50ZPA

16
228 =1v
229 =2v
227 =2v
LEGEND
FLA — Full Load Amps
LRA — Locked Rotor Amps
MCA -- Minimum Circuit Amps
MOCP — Maximum Overcurrent Protection
RLA — Rated Load Amps
NOTES:
1. In compliance with NEC (National Electrical Code) requirements
for multimotor and combination load equipment (refer to NEC
Articles 430 and 440), the overcurrent protective device for the
unit shall be Power Supply fuse. The CGA (Canadian Gas
Association) units may be fuse or circuit break er.
2. Minimum wire size is based on 60 C copper wire. If other than
60 C wire is used, or if length exceeds wire length in table,
determine siz e from NEC..
3. Unbalanced 3-Phase Supply Voltage
Never operate a motor where a phase imbalance in supply volt-
age is greater than 2%.
Use the following formula to determine
the percentage of voltage imbalance.
% Voltage imbalance
max voltage deviation from average voltage
= 100 x average voltage
EXAMPLE: Supply voltage is 230-3-60.
AB = 228 v
BC = 231 v
AC = 227 v
228 + 231 + 227
Average Voltage = 3
686
=3
= 229
Determine maximum deviation from average voltage.
(AB) 229 -
(BC) 231 -
(AC) 229 -
Maximum deviation is 2 v.
Determine percent of voltage imbalance.
2
% Voltage Imbalance = 100 x 229
= 0.8%
This amount of phase imbalance is satisfactory as it is below the
maximum allowable 2%.
IMPORTANT: If the supply voltage phase imbalance is
more than 2%, contact your local electric utility company
immediately.
®
*
Heater capacity (kW) based on heater voltage of 208v & 240v.
If power distribution voltage to unit varies from rated heater
volta
g
e, heater kW will var
y
accordin
g
l
y
.
o
o
C03014
Fig. 18 -- Electrical Data Table Legend
Table 6—Dry Coil Air Delivery* Horizontal Discharge
(Deduct 10 percent for 208 Volt Operation)
230 VOLT HORIZONTAL DISCHARGE
UNIT
SIZE
SPEED
TAP
AIR
DELIVERY
EXTERNAL STATIC PRESSURE (IN.WG)
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
024
1Watts —99 100 118 130 142 — — — —
CFM —848 793 757 698 632 — — — —
2Watts — — — — — 222 233 244 257 260
CFM — — — — — 970 918 861 795 729
030
2Watts —155 146 157 170 — — — — —
CFM —1108 995 951 884 — — — — —
3Watts — — — — — 261 275 286 291 315
CFM — — — — — 1117 1053 1014 980 877
036
1Watts 180 166 179 191 204 216 — — — —
CFM 1344 1215 1172 1136 1095 1051 — — — —
2Watts — — — 261 276 290 301 316 329 342
CFM — — — 1343 1304 1272 1234 1190 1148 1100
042
3Watts 269 283 305 321 336 349 360 — — —
CFM 1440 1404 1369 1333 1301 1273 1239 — — —
4Watts — — 418 432 450 465 480 490 503 518
CFM — — 1572 1543 1504 1475 1441 1418 1380 1332
048
1Watts —204 209 216 229 236 249 — — —
CFM —1129 1087 1027 994 932 881 — — —
2Watts — — 233 245 254 266 276 289 — —
CFM — — 1164 1122 1066 1025 954 906 — —
3Watts 386 398 409 418 425 435 438 441 451 —
CFM 1680 1652 1625 1583 1555 1515 1477 1444 1403 —
4Watts —440 448 457 462 469 477 480 485 486
CFM —1745 1717 1684 1651 1612 1573 1537 1508 1470
060
1Watts 224 235 251 266 277 291 298 — — —
CFM 1334 1288 1259 1224 1181 1157 1117 — — —
2Watts — — 286 301 311 325 333 344 370 —
CFM — — 1333 1296 1261 1232 1199 1170 1062 —
3Watts 608 626 643 660 668 685 697 — — —
CFM 1931 1900 1878 1844 1817 1789 1755 — — —
4Watts 737 755 770 787 799 817 826 812 782 —
CFM 2093 2061 2028 2001 1971 1934 1899 1850 1757 —
*Air delivery values are based on operating voltage of 230v, wet coil, without filter or electric heater. Deduct filter and electric heater pressure drops to obtain
static pressure available for ducting.
NOTES:
1. Do not operate the unit at a cooling airflow that is less than 350 cfm for each 12,000 Btuh of rated cooling capacity. Evaporator coil frosting may occuratair-
flows below this point.
2. Dashes indicate portions of table that are beyond the blower motor capacity or are not recommended.
50ZPA

17
Table 7—Cooling Charging Chart
SUCTION LINE TEMPERATURE (°F)
Suction Line Pressure (PSIG)
OD Temp.
(°F) 52 54 56 59 61 64 67 70 73 76 79 82 85 89 92
45 51 55 60 64 69 — — — — — — — — — —
55 — — 53 57 62 66 70 — — — — — — — —
65 — — — — 53 57 62 66 71 75 — — — — —
75 — — — — — — — 56 61 66 71 76 — — —
85 — — — — — — — — 53 58 63 67 72 — —
95 — — — — — — — — — 50 54 58 62 66 —
105 — — — — — — — — — — 50 53 57 60 64
115 — — — — — — — — — — 49 52 55 58 61
125 — — — — — — — — — — — 50 53 56 59
SUCTION LINE TEMPERATURE (°C)
Suction Line Pressure (kPa)
OD Temp.
(°C) 361 370 387 405 423 442 462 482 502 523 544 566 589 612 636
711 13 15 18 21 — — — — — — — — — —
13 — — 12 14 16 19 21 — — — — — — — —
18 — — — — 12 14 17 19 21 24 — — — — —
24 — — — — — — — 13 16 19 22 24 — — —
29 — — — — — — — — 12 14 17 20 22 — —
35 — — — — — — — — — 10 12 14 17 19 —
41 — — — — — — — — — — 10 12 14 16 18
46 — — — — — — — — — — 9 11 13 14 16
52 — — — — — — — — — — — 10 11 13 15
COOLING OPERATION (SIZES 048 AND 060)
These units utilize a 2 stage indoor thermostat. With a first stage call
for cooling (Y1), the indoor fan (low stage) energizes immediately
whereas the contactor energizes after a 5 minute time delay (in case
of an initial start--up) starting the compressor (low stage) and the
outdoor fan motor. If the low stage operation cannot satisfy the
cooling demand, the second stage cooling (Y2) energizesswitching
the compressor into high stage cooling through energizing an
internal solenoid valve inside the scroll compressor and switching
the indoor fan into high stage. When second stage cooling is
satisfied, Y2 de--energizes switching the compressorand the indoor
fan into low stage cooling. When the low stage cooling demand is
met, Y1 de--energizes shutting the compressor, indoor fan and the
outdoor fan.
HEATING OPERATION (SIZES 024--042)
With a call for heating (Y1), the indoor fan (low stage) energizes
immediately whereas the contactor energizes after a 5 minute time
delay (in case of initial start--up) starting the compressor and the
outdoor fan motor. If Y/Y2 cannot satisfy the heating demand, the
auxiliary or backup heat (W2) energizes. In case of staged heating,
W3 is energized if the demand is not met. The highest airflow
selected is run while the electric heat is in operation. When heating
demand is met, W3, W2 and Y/Y2 sequentially de--energize
shutting the compressor, indoor fan and the outdoor fan.
HEATING OPERATION (SIZES 048 AND 060)
With a first stage call for heating (Y1), the indoor fan (low stage)
energizes immediately whereas the contactor energizes after a 5
minute time delay (in case of initial start--up) starting the compressor
(low stage) and the outdoor fan motor. If the low stage oepration
cannot satisfy the heating demand, the second stage heating (Y2)
energizes switching the compressor into high stage heating through
energizing an internal solenoid valve inside the scroll compressor
and switching the indoor fan into high stage. The auxiliary or
backup heat is controlled by a third stage (W2). If the demand is not
met, W3 is energized in case of staged heating. When heating
demand is satisfied, W3, W2 and Y2 sequentially de--energize
switching the compressor and the indoor fan into low stage heating.
When the low stage heating demand is met, Y1 de--energizes
shutting the compressor, indoor fan and the outdoor fan.
CONTINUOUS FAN
With the continuous Indoor fan option selected on the thermostat,
G is continuously energized. In case of 024--042 units, the selected
airflow setting is provided. In case of 048 and 060 units, the system
runs low stage (Y1) airflow for continuous fan operation.
DEFROST
Defrost board (DB) is a time and temperature control, which
includes a field--selectable time period between checks for defrost
(30, 60, 90 and 120 minutes). The time period is factory--set at 60
minutes and should only be adjusted by a trained service person.
Electronic timer and defrost cycle start only when contactor is
energized and defrost thermostat (DFT) is closed.
Defrost mode is identical to Cooling mode. The outdoor fan motor
stops because of “OF1” and “OF2” contacts opening on the defrost
board,a bank of optionalelectricheatturnson to warm airsupplying
the conditioned space.
ELECTRIC RESISTANCE HEATING
If accessory electric heaters are installed, on a call for “Emergency
Heat” the thermostat energizes W which energizes the heater relay
and in turn energizes the electric heaters. The IFR is energized
which starts the indoor--fan motor. If the heaters are staged, W2 is
energized when the second stage of heating is required. When the
need for heating is satisfied, the heater and IFM are de--energized.
MAINTENANCE
To ensure continuing high performance, and to minimize the
possibility of premature equipment failure, periodic maintenance
must be performed on this equipment. This cooling unit should be
inspected at least once each year by a qualified service person. To
troubleshoot unit, refer to Troubleshooting Chart in back of book.
NOTE TO EQUIPMENT OWNER: Consult your local dealer
about the availability of a maintenance contract.
50ZPA

18
PERSONAL INJURY AND UNIT DAMAGE HAZARD
Failure to follow this warning could result in personal injury
or death and possible unit component damage.
The ability to properly perform maintenance on this
equipment requires certain expertise, mechanical skills, tools
and equipment. If you do not possess these, do not attempt to
perform any maintenance on this equipment, other than those
procedures recommended in the Owner’s Manual.
!
WARNING
The minimum maintenance requirements for this equipment are as
follows:
1. Inspect air filter(s) each month. Clean or replace when
necessary.
2. Inspect indoor coil, drain pan, and condensate drain each
cooling season for cleanliness. Clean when necessary.
3. Inspect blower motor and wheel for cleanliness each cooling
season. Clean when necessary.
4. Check electrical connections for tightness and controls for
proper operation each cooling season. Service when
necessary.
5. Ensure electric wires are not in contact with refrigerant
tubing or sharp metal edges.
ELECTRICAL SHOCK HAZARD
Failure to follow these warnings could result in personal
injury or death:
1. Turn off electrical power to the unit before performing any
maintenance or service on this unit.
2. Use extreme caution when removing panels and parts.
3. Never place anything combustible either on or in contact
with the unit.
!
WARNING
Step 1—Air Filter
IMPORTANT: Never operate the unit without a suitable air filter
in the return--air duct system. Always replace the filter with the same
dimensional size and type as originally installed. See Table 1 for
recommended filter sizes.
Inspect air filter(s) at least once each month and replace
(throwaway--type) or clean (cleanable--type) at least twice during
each cooling season and twice during the heating season, or
whenever the filter becomes clogged with dust and lint.
Step 2—Unit Top Removal (Outdoor--Coil Side)
NOTE: When performing maintenance or service procedures that
require removal of the unit top, be sure to perform all of the routine
maintenance procedures that require top removal, including coil
inspection and cleaning, and condensate drain pan inspection and
cleaning.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Disconnect and tag electrical power to the unit before
removing top.
!
WARNING
Only qualified service personnel should perform maintenance and
service procedures that require unit top removal.
Refer to the following top removal procedures:
1. Remove screws on unit top cover surface. (Save all screws.)
2. Remove screws on unit top cover flange. (Save all screws.)
3. Lift top from unit carefully. Set top on edge and make sure
that top is supported by unit side that is opposite duct (or
plenum) side.
4. Carefully replace and secure unit top to unit, using screws
removed in Steps 1 and 2, when maintenance and/or service
procedures are completed.
Step 3—Indoor Blower and Motor
For longerlife, operating economy, and continuing efficiency, clean
accumulated dirt and grease from the blower wheel and motor
annually.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Disconnect and tag electrical power to the unit before cleaning
and lubricating the blower motor and wheel.
!
WARNING
To clean the blower wheel:
1. Remove the blower housing:
a. Remove the screws on the external side of the duct panel
that fasten the housing to the duct panel assembly.
b. Remove the side access panel and unscrew the mounting
bracket that fastens the blower housing to the internal
partition panel fo the control box assembly.
c. Make sure that the blower housing is supported by hand
before completely removing the mounting bracket.
d. Slide the blower housing from the rails of the duct panel
and place it outside the unit.
2. Remove the blower wheel from the housing:
a. Loosen the set screw which secures the wheel to the motor
shaft.
b. Loosen thethreemounting legsof the motor by removing
the bolts that fasten themounting legs to the housing.
c. Slide out the motor assembly (motor, belly band and the
3 mounting legs) from the hub of the wheel.
d. Remove the filler panel at the discharge end of the blower
housing by removing the two screws that fasten it to the
housing.
e. Remove the wheel form the housing.
3. Remove the caked on dirt from the wheel and the motor
using a brush.
4. Remove lint and dirt accumulations from the wheel and
housing with a vacuum cleaner, using a soft brush
attachment.
5. Remove grease and oil with a mild solvent.
6. Reassemble
a. Slip the wheel back in the housing with the hub set screw
parented in the correct direction.
b. Install the filler panel.
c. Reinsert the motor assembly in the wheel hub and align
the mounting legs with the housing mounting hold
locations.
d. Tighten the mounting bolts to fasten the motor assembly
with the housing.
50ZPA

19
Table 8—Wet Coil Pressure Drop
UNIT
SIZE
STANDARD CFM (S.C.F.M.)
600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000
024 .027 .034 040 .047 .053 -- -- -- -- -- -- -- -- -- --
030 -- .036 .042 .050 .055 .063 .072 .081 -- -- -- -- -- -- --
036 -- -- -- .050 .055 .063 .072 .081 .090 .097 -- -- -- -- --
042 -- -- -- -- .042 .049 .052 .059 .065 .071 .078 .085 .091 -- --
048 -- -- -- -- -- -- .072 .081 .090 .097 .108 .120 .129 .139 --
060 -- -- -- -- -- -- -- -- -- .071 .078 .085 .091 .098 .114
Table 9—Filter Pressure Drop (in. wg)
UNIT SIZE
FILTER
SIZE
(in.)
CFM
500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300
024--036 24 x 24 0.06 0.07 0.08 0.08 0.09 0.09 0.09 0.10 0.11 0.12 0.14 0.15 — — — — — — —
042--060 30 x 30 — — — — — — — — 0.08 0.09 0.10 0.11 0.12 0.13 0.14 0.15 0.16 0.17 0.18
Table 10—Accessory Electric Heat Pressure Drop (in. wg)
HEATER kW CFM
600 800 1000 1200 1400 1600 1800 2000 2200
5--20 0.06 0.08 0.10 0.13 0.15 0.18 0.20 0.23 0.25
e. Center the wheel in the housing by sliding it, align the flat
end of the shaft with the set screw and tighten the set
screw.
f. Slide back the blower housing into the mounting rails in
the duct panel and install the mounting bracket back in its
position.
g. Install the screws on the external side of the duct panel to
fasten duct panel with the housing.
h. Replace the side access panel.
Step 4—Outdoor Coil, Indoor Coil, and Condensate Drain
Pan
Inspect the condenser coil, evaporator coil, and condensate drain
pan at least once each year.
The coils are easily cleaned when dry; therefore, inspect and clean
the coils either before or after each cooling season. Remove all
obstructions, including weeds and shrubs, that interfere with the
airflow through the condenser coil.
Straighten bent fins with a fin comb. If coated with dirt or lint, clean
the coils with a vacuum cleaner, using the soft brush attachment. Be
careful not to bend the fins. If coated with oil or grease, clean the
coils with a mild detergent and water solution. Rinse coils with clear
water, using a garden hose. Be carefulnot to splash water on motors,
insulation, wiring, or air filter(s). For best results, spray condenser
coil fins from inside to outside the unit. On units with an outer and
inner condenser coil, be sure to clean between the coils. Be sure to
flush all dirt and debris from the unit base.
Inspect the drain pan and condensate drain line when inspecting the
coils. Clean the drain pan and condensate drain by removing all
foreign matter from the pan. Flush the pan and drain trough with
clear water. Do not splash water on the insulation, motor, wiring, or
air filter(s). If the drain trough is restricted, clear it with a “plumbers
snake” or similar probe device.
Step 5—Outdoor Fan
UNIT OPERATION HAZARD
Failure to follow this caution may result in damage to unit
components.
Keep the condenser fan free from all obstructions to ensure
proper cooling operation. Never place articles on top of unit.
CAUTION
!
1. Shut off unit power supply and install lockout tag.
2. Remove outdoor--fan assembly (grille, motor, motor cover,
and fan) by removing screws and flipping assembly onto
unit top cover.
3. Loosen fan hub setscrews.
4. Adjust fan height as shown in Fig. 19.
5. Tighten setscrews.
6. Replace outdoor--fan assembly.
12m
m
A06411
Fig. 19 -- Outdoor Fan Adjustment
Step 6—Electrical Controls and Wiring
Inspect and check the electrical controls and wiring annually. Be
sure to turn off the electrical power to the unit.
Remove access panel to locate all the electrical controls and wiring.
Check all electrical connections for tightness. Tighten all screw
connections. If any smoky or burned connections are noticed,
disassemble the connection, clean all theparts, re--strip the wireend
and reassemble the connection properly and securely.
Check to ensure no wires are touching refrigerant tubing or sharp
sheet metal edges. Move and secure wires to isolate from tubing and
sheet metal edges.
After inspecting the electrical controls and wiring, replace all the
panels. Start the unit, and observe at least one complete cooling
cycle to ensure proper operation. If discrepancies are observed in
operating cycle, or if a suspected malfunction has occurred, check
each electrical component with the proper electrical
instrumentation. Refer to the unit wiring label when making these
checks.
Step 7—Refrigerant Circuit
Inspect all refrigerant tubing connections and the unit base for oil
accumulation annually. Detecting oil generally indicates a
refrigerant leak.
If oil is detected or if low performance is suspected, leak test all
refrigerant tubing using an electronic leak detector, or liquid--soap
50ZPA50ZPA

20
solution. If a refrigerant leak is detected, refer to Check for
Refrigerant Leaks section.
If no refrigerant leaks are found and low performance is suspected,
refer to Checking and Adjusting Refrigerant Charge section.
Step 8—Indoor Airflow
Theheating and/orcooling airflowdoesnot require checking unless
improper performance is suspected. If a problem exists, be sure that
all supply-- and return--air grilles are open and free from
obstructions, and that the air filter is clean.
Step 9—Metering Devices
Refrigerant cooling metering device is an AccuRater (024--042) or
TXV (048 and 060) located upstream of the indoor coil distributor
assembly. Refrigerant heating mode metering device is an
AccuRater located upstrem of the outdoor coil distributorassembly.
Step 10—Liquid Line Strainers
The liquid line strainers (to protect metering devices) are made of
wire mesh and are located in the liquid lines on the inlet side of the
metering devices.
Step 11—High Flow Valves
High flow valves are located on the compressor hot gas and suction
tubes. Large black plastic caps distinguish these valves with
O--rings located inside the caps. These valves can not be accessed for
service in the field. Ensure the plastic caps are in place and tight or
the possibility of refrigerant leakage could occur.
TROUBLESHOOTING
Refer to the Troubleshooting Chart (Table 11) for troubleshooting
information.
START--UP CHECKLIST
Use the Start--Up Checklist at the back of this manual.