Carrier 50LC 14 Installation and user guide

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Catalog No. 04-53500167-01 Printed in U.S.A. Form 50LC-14-26-03SM Pg 1 2-2020 Replaces: 50LC-14-26-02SM
Service and Maintenance Instructions
CONTENTS
SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . 1
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Routine Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . 2
SUPPLY FAN (BLOWER) SECTION . . . . . . . . . . . . . . 3
Supply Fan Assembly . . . . . . . . . . . . . . . . . . . . . . . . . 3
Changing Fan Wheel Speed by Changing Pulleys . . 4
COOLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Evaporator Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Coil Maintenance and Cleaning Recommendation. . 5
Evaporator Coil Metering Devices . . . . . . . . . . . . . . . 6
Refrigerant System Pressure Access Ports . . . . . . . 6
PURON® (R-410A) REFRIGERANT. . . . . . . . . . . . . . . 6
Refrigerant Charge. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Evacuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Compressors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Condenser-Fan Adjustment . . . . . . . . . . . . . . . . . . . 13
Troubleshooting Cooling System. . . . . . . . . . . . . . . 13
CONVENIENCE OUTLETS . . . . . . . . . . . . . . . . . . . . . 15
Wet in Use Convenience Outlet Cover. . . . . . . . . . . 15
Duty Cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Non-Powered Type. . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Unit-Powered Type. . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Fuse On Powered Type . . . . . . . . . . . . . . . . . . . . . . . 17
Using Unit-Mounted Convenience Outlets . . . . . . . 17
SMOKE DETECTORS . . . . . . . . . . . . . . . . . . . . . . . . . 17
System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Smoke Detector Locations . . . . . . . . . . . . . . . . . . . . 18
FIOP Smoke Detector Wiring and Response. . . . . . 19
Sensor and Controller Tests . . . . . . . . . . . . . . . . . . . 19
Controller Alarm Test Procedure . . . . . . . . . . . . . . . 20
Dirty Controller Test Procedure . . . . . . . . . . . . . . . . 20
Dirty Sensor Test Procedure. . . . . . . . . . . . . . . . . . . 20
Changing the Dirty Sensor Test . . . . . . . . . . . . . . . . 20
To Configure the Dirty Sensor Test Operation . . . . 20
SD-TRK4 Remote Alarm Test Procedure . . . . . . . . . 20
Detector Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Resetting Alarm and Trouble Condition Trips . . . . 22
Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
PROTECTIVE DEVICES . . . . . . . . . . . . . . . . . . . . . . . 22
Compressor Protection . . . . . . . . . . . . . . . . . . . . . . . 22
Supply (Indoor) Fan Motor Protection . . . . . . . . . . . 23
Condenser Fan Motor Protection . . . . . . . . . . . . . . . 23
Control Circuit, 24-V . . . . . . . . . . . . . . . . . . . . . . . . . 23
ELECTRIC HEATERS . . . . . . . . . . . . . . . . . . . . . . . . . 23
Single Point Boxes and Supplementary Fuses . . . .24
Safety Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Low-Voltage Control Connections . . . . . . . . . . . . . .25
WIRING DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . .25
PRE-START-UP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
START-UP, GENERAL . . . . . . . . . . . . . . . . . . . . . . . .31
Unit Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Return-Air Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Outdoor-Air Inlet Screens . . . . . . . . . . . . . . . . . . . . .31
Compressor Mounting . . . . . . . . . . . . . . . . . . . . . . . .31
Internal Wiring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Refrigerant Service Ports. . . . . . . . . . . . . . . . . . . . . .31
Compressor Rotation . . . . . . . . . . . . . . . . . . . . . . . . .32
Cooling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Heating. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Ventilation (Continuous Fan). . . . . . . . . . . . . . . . . . .32
RTU Open Control System. . . . . . . . . . . . . . . . . . . . .34
SYSTEMVU™ (FACTORY OPTION). . . . . . . . . . . . . .34
Integrated Staging Control (ISC) Board . . . . . . . . . .34
EconoMi$er® X (Factory Option) . . . . . . . . . . . . . . .36
Staged Air Volume (SAV™) with Variable Frequency
Drive. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
Multi-Speed VFD Display Kit (Field-Installed
Option). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
FASTENER TORQUE VALUES. . . . . . . . . . . . . . . . . .62
SEQUENCE OF OPERATION . . . . . . . . . . . . . . . . . . .62
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62
Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63
Cooling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63
Economizer (Optional) . . . . . . . . . . . . . . . . . . . . . . . .63
Low Ambient Cooling Operation down to 40°F
(4°C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63
Heating. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63
6APPENDIX A — MODEL NUMBER
NOMENCLATURE . . . . . . . . . . . . . . . . . . . . . . . . . .64
APPENDIX B — PHYSICAL DATA . . . . . . . . . . . . . . .65
APPENDIX C — FAN PERFORMANCE . . . . . . . . . . .72
START-UP CHECKLIST . . . . . . . . . . . . . . . . . . . . .CL-1
SAFETY CONSIDERATIONS
Installation and servicing of air-conditioning equipment can be
hazardous due to system pressure and electrical components. Only
trained and qualified service personnel should install, repair, or
service air-conditioning equipment.
Untrained personnel can perform basic maintenance functions of
cleaning coils and filters and replacing filters. All other operations
should be performed by trained service personnel. When working
on air-conditioning equipment, observe precautions in the
literature, tags and labels attached to the unit, and other safety
precautions that may apply.
WeatherExpert®
50LC*D14-D26
Single Package Rooftop Cooling Only
with Puron®(R-410A) Refrigerant

2
Follow all safety codes, including ANSI (American National
Standards Institute) Z223.1. Wear safety glasses and work gloves.
Use quenching cloth for unbrazing operations. Have fire
extinguisher available for all brazing operations.
It is important to recognize safety information. This is the safety-
alert symbol . When you see this symbol on the unit and in
instructions or manuals, be alert to the potential for personal
injury.
Understand the signal words DANGER, WARNING,
CAUTION, and NOTE. These words are used with the safety-
alert symbol. DANGER identifies the most serious 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 enhanced installation,
reliability, or operation.
General
Figure 1 and 2 show general unit arrangement and access
locations.
Fig. 1 — Typical Access Panel Locations (Rear)
Fig. 2 — Typical Access Panel Locations (Front)
Routine Maintenance
These items should be part of a routine maintenance program,
to be checked every month or two, until a specific schedule for
each can be identified for this installation:
QUARTERLY INSPECTION (AND 30 DAYS AFTER INI-
TIAL START)
• Return air filter replacement
• Outdoor hood inlet filters cleaned
• Belt tension checked
• Belt condition checked
• Pulley alignment checked
• Fan shaft bearing locking collar tightness checked
• Condenser coil cleanliness checked
• Condensate drain checked
SEASONAL MAINTENANCE
These items should be checked at the beginning of each season
(or more often if local conditions and usage patterns dictate):
AIR CONDITIONING
• Condenser fan motor mounting bolts tightness
• Compressor mounting bolts
• Condenser fan blade positioning
• Control box cleanliness and wiring condition
• Wire terminal tightness
• Refrigerant charge level
• Evaporator coil cleaning
• Evaporator blower motor amperage
HEATING
• Power wire connections
• Fuses ready
• Manual-reset limit switch is closed
ECONOMIZER OR OUTSIDE AIR DAMPER
• Inlet filters condition
• Check damper travel (economizer)
• Check gear and dampers for debris and dirt
AIR FILTERS AND SCREENS
Each unit is equipped with return air filters. If the unit has an
economizer, it will also have an outside air screen. If a manual
WARNING
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal inju-
ry or death.
Before performing service or maintenance operations on
unit, LOCKOUT/TAGOUT the main power switch to unit.
Electrical shock and rotating equipment could cause severe
injury.
WARNING
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal inju-
ry or death.
Units with convenience outlet circuits may use multiple
disconnects. Check convenience outlet for power status be-
fore opening unit for service. Locate its disconnect switch,
if appropriate, and open it. Lock-out and tag-out this
switch, if necessary.
WARNING
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this warning could cause personal injury,
death and/or equipment damage.
R-410A refrigerant systems operate at higher pressures than
standard R-22 systems. Do not use R-22 service equipment or
components on R-410A refrigerant equipment.
CAUTION
PERSONAL INJURY HAZARD
Failure to follow this caution may result in personal injury.
Sheet metal parts may have sharp edges or burrs. Use care
and wear appropriate protective clothing, safety glasses and
gloves when handling parts and servicing air conditioning
equipment.
FILTER
ACCESS
PANEL
ELECTRIC HEAT
ACCESS PANEL
CONTROL
BOX
ACCESS
PANEL
FILTER
AND
INDOOR
COIL
ACCESS
PA N E L
INDOOR
BLOWER
ACCESS
PA N E L

3
outside air damper is added, an inlet air screen
will also be present.
Each of these filters and screens will need to be periodically re-
placed or cleaned.
RETURN AIR FILTERS
Return air filters are disposable fiberglass media type. Access
to the filters is through the vertical panel to the right of the con-
trol box. Filters are situated on slide-out racks for easy inspec-
tion and repair. (See Fig. 1.)
To remove the filters:
1. Remove vertical filter access door.
2. Reach in and extract the filters from the filter rack.
3. Replace these filters as required with similar replacement
filters of same size. Observe the flow direction arrows on
the side of each filter frame.
4. Re-install filter access panel.
OUTSIDE AIR HOOD
Outside air hood inlet screens are permanent aluminum-mesh
type filters. Check these for cleanliness.
Remove the screens when cleaning is required. Clean by wash-
ing with hot low-pressure water and soft detergent and replace
all screens before restarting the unit. Observe the flow direc-
tion arrows on the side of each filter frame.
ECONOMIZER AND MANUAL OUTSIDE AIR SCREENS
This air screen is retained by spring clips under the top edge of
the hood. (See Fig. 3.)
Fig. 3 — Filter Installation
To remove the filter, remove screws in horizontal filter retain-
ers on leading edge of hood. Slide filters out. To re-install fil-
ters, slide clean or new filters into hood side retainers. Once
positioned, re-install horizontal filter retainer.
SUPPLY FAN (BLOWER) SECTION
Supply Fan Assembly
The supply fan system consists of two forward-curved centrif-
ugal blower wheels mounted on a solid blower shaft that is
supported by two greaseable pillow block concentric bearings.
A fixed-pitch driven (fan) pulley is attached to the fan shaft
and an adjustable-pitch driver pulley is mounted on the motor.
The pulleys are connected using a “V” type belt. (See Fig. 4.)
Fig. 4 — Belt Drive Motor Mounting
BELT
Check the belt condition and tension quarterly. Inspect the belt
for signs of cracking, fraying or glazing along the inside sur-
faces. Check belt tension by using a spring-force tool (such as
Browning’s “Belt Tension Checker” or equivalent tool); ten-
sion should be between 5 and 10 lbs with 5/8-in. deflection
when measured at the centerline of the belt span. This point is
at the center of the belt when measuring the distance between
the motor shaft and the blower shaft.
NOTE: Without the spring-tension tool, place a straight edge
across the belt surface at the pulleys, then deflect the belt at mid-
span using one finger to a 1/2-in. deflection.
Adjust the belt tension by loosening the four motor mounting
nuts and bolts where the motor bolts to the blower rail. There
are two jack bolts and nuts that are used to slide the motor plate
to either increase or decrease belt tension. There are locking
nuts on the jack bolts that need to be loosened at the motor
plate. Turn the jack bolts clockwise or counter clockwise until
the correct belt tension is achieved. Ensure the fan shaft and
motor shaft are parallel prior to tightening motor plate nuts.
(See Fig. 5.)
Fig. 5 — Adjusting Belt Tension
IMPORTANT: DO NOT OPERATE THE UNIT WITH-
OUT THESE FILTERS!
WARNING
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal inju-
ry or death.
Before performing service or maintenance operations on
unit, LOCKOUT/TAGOUT the main power switch to unit.
Electrical shock and rotating equipment could cause severe
injury.
Step 1: Loosen
motor bolts
Step 2: Loosen jack bolt
lock nuts
Step 3: Loosen or tighten
jack boltsuntil proper
belt tension isachieved

4
To replace the belt:
1. Use a belt with same section type or similar size. Do not
substitute a “FHP” type belt. When installing the new belt,
do not use a tool (screwdriver or pry-bar) to force the belt
over the pulley flanges. This will stress the belt and cause
a reduction in belt life.
2. Loosen the motor mounting plate front bolts and rear
bolts.
3. Loosen the Jack bolt lock nuts and using the Jack bolts
relieve the belt tension to allow easy removal of the belt
by hand.
4. Remove the belt by gently lifting the old belt over one of
the pulleys.
5. Install the new belt by gently sliding the belt over both
pulleys, then using the Jack bolts slide the motor plate
away from the fan housing until proper belt tension is
achieved.
6. Check the alignment of the pulleys; adjust if necessary.
7. Tighten all nuts to motor plate and Jack bolts.
8. Check the tension after a few hours of runtime and re-
adjust as required.
ADJUSTABLE-PITCH PULLEY ON MOTOR
The motor pulley is an adjustable-pitch type that allows a ser-
vicer to implement changes in the fan wheel speed to match as-
installed ductwork systems. The pulley consists of a fixed
flange side that faces the motor (secured to the motor shaft)
and a movable flange side that can be rotated around the fixed
flange side that increases or reduces the pitch diameter of this
driver pulley. (See Fig. 6.)
Fig. 6 — Supply-Fan Pulley Adjustment
As the pitch diameter is changed by adjusting the position of
the movable flange, the centerline on this pulley shifts laterally
(along the motor shaft). This creates a requirement for a re-
alignment of the pulleys after any adjustment of the movable
flange. Also reset the belt tension after each realignment.
Check the condition of the motor pulley for signs of wear.
Glazing of the belt contact surfaces and erosion on these sur-
faces are signs of improper belt tension and/or belt slippage.
Pulley replacement may be necessary.
To change fan speed:
1. Shut off unit power supply and install lock-out tag.
2. Loosen belt by loosening the motor adjustment bolts as
described in the Belt Adjustment section above. (See
Fig. 4.)
3. Loosen movable pulley flange setscrew. (See Fig. 6.)
4. Screw movable flange toward fixed flange to increase
speed and away from fixed flange to decrease speed.
Increasing fan speed increases load on motor. Do not
exceed maximum speed listed in the Product Data or
motor amperage as listed on the unit rating plate.
5. Set movable flange at nearest keyway or flat of pulley hub
and tighten setscrew to torque specifications. Torque pul-
ley set screw to 72 ± 5 (in. lbs).
To align fan and motor pulleys:
1. Loosen fan pulley setscrews.
2. Slide fan pulley along fan shaft. Make angular alignment
by loosening motor from mounting.
3. Tighten fan pulley setscrews and motor mounting bolts to
torque specifications.
4. Recheck belt tension.
BEARINGS
This fan system uses bearings featuring concentric split lock-
ing collars. The collars are tightened through a cap screw
bridging the split portion of the collar. The cap screw has a
Torx T25 socket head. To tighten the locking collar, hold the
locking collar tightly against the inner race of the bearing and
torque the cap screw to 65 to 70 in. lb (7.4 to 7.9 Nm). (See
Fig. 7.)
Fig. 7 — Tightening Locking Collar
MOTOR
When replacing the motor, also replace the external-tooth lock
washer (star washer) under the motor mounting base; this is
part of the motor grounding system. Ensure the teeth on the
lock washer bite through and are in contact with the motor’s
painted base. Tighten motor mounting bolts to 120 ± 12 in. lbs.
Changing Fan Wheel Speed by Changing Pulleys
The horsepower rating of the belt is primarily dictated by the
pitch diameter of the smaller pulley in the drive system (typi-
cally the motor pulley in these units). Do not install a replace-
ment motor pulley with a smaller pitch diameter than provided
on the original factory pulley. Change fan wheel speed by
changing the fixed sheave fan pulley (larger pitch diameter to
reduce wheel speed, smaller pitch diameter to increase wheel
speed) or select a new system (both pulleys and matching
belt(s)).
Before changing pulleys to increase fan wheel speed, check the
fan performance at the target speed and airflow rate to deter-
mine new motor loading (bhp). Use the fan performance tables
or use the Packaged Rooftop Builder software program. Con-
firm that the motor in this unit is capable of operating at the
new operating condition. Fan shaft loading increases dramati-
cally as wheel speed is increased.
To reduce vibration, replace the motor’s adjustable pitch pulley
with a fixed pitch pulley (after the final airflow balance adjust-
ment). This will reduce the amount of vibration generated by
the motor/belt-drive system. To determine variable pitch pulley
diameter perform the following calculation:
1. Determine full open and full closed pulley diameter.
2. Subtract the full open diameter from the full closed diameter.
STRAIGHT EDGE
MUST BE PARALLEL
WITH BELT
SETSCREWS
MOTOR AND
FANSHAFTS
MUST BE
PARALLEL
FIXED FLANGE
MOVABLE
FLANGE
SINGLE - GROOVE
FAN PULLEY
MOTOR PULLEY
T --- 2 5 T O R X S O C K E T
HEAD CAP SCREW
LOCKING COLLAR

5
3. Divide that number by the number of pulley turns open
from full closed.
This number is the change in pitch datum per turn open.
EXAMPLE
• Pulley dimensions 2.9 to 3.9 (full close to full open)
• 3.9 – 2.9 = 1
• 1 divided by 5 (turns from full close to full open)
• 0.2 change in pulley diameter per turn open
• 2.9 + 0.2 = 3.1-in. pulley diameter when pulley closed one
turn from full open
COOLING
Evaporator Coil
The evaporator coil is traditional round-tube, plate-fin technol-
ogy. Tube and fin construction is of various optional materials
and coatings (see Appendix A). Coils are multiple-row. On two
compressor units, the evaporator coil is a face split design,
meaning the two refrigerant circuits are independent in the
coil. The bottom portion of the coil will always be circuit A,
with the top of the coil being circuit B.
Coil Maintenance and Cleaning Recommendation
Routine cleaning of coil surfaces is essential to maintain proper
operation of the unit. Elimination of contamination and remov-
al of harmful residues will greatly increase the life of the coil
and extend the life of the unit. The following maintenance and
cleaning procedures are recommended as part of the routine
maintenance activities to extend the life of the coil.
REMOVE SURFACE LOADED FIBERS
Surface loaded fibers or dirt should be removed with a vacuum
cleaner. If a vacuum cleaner is not available, a soft non-metal-
lic bristle brush may be used. In either case, the tool should be
applied in the direction of the fins. Coil surfaces can be easily
damaged (fin edges can be easily bent over and damage to the
coating of a protected coil) if the tool is applied across the fins.
NOTE: Use of a water stream, such as a garden hose, against a
surface loaded coil will drive the fibers and dirt into the coil. This
will make cleaning efforts more difficult. Surface loaded fibers
must be completely removed prior to using low velocity clean wa-
ter rinse.
PERIODIC CLEAN WATER RINSE
A periodic clean water rinse is very beneficial for coils that are
applied in coastal or industrial environments. However, it is
very important that the water rinse is made with very low ve-
locity water stream to avoid damaging the fin edges. Monthly
cleaning as described below is recommended.
ROUTINE CLEANING OF EVAPORATOR COIL SURFACES
Monthly cleaning with Totaline environmentally sound coil
cleaner is essential to extend the life of coils. This cleaner is
available from Carrier Replacement parts division as part
number P902-0301 for one gallon container, and part number
P902-0305 for a 5 gallon container. It is recommended that all
round tube coil cleaner as described below. Coil cleaning
should be part of the unit’s regularly scheduled maintenance
procedures to ensure long life of the coil. Failure to clean the
coils may result in reduced durability in the environment.
Avoid the use of
• coil brighteners
• acid cleaning prior to painting
• high pressure washers
• poor quality water for cleaning
Totaline environmentally sound coil cleaner is non-flammable,
hypoallergenic, non-bacterial, and a USDA accepted biode-
gradable agent that will not harm coil or surrounding compo-
nents such as electrical wiring, painted metal surfaces, or insu-
lation. Use of non-recommended coil cleaners is strongly dis-
couraged since coil and unit durability could be affected.
Totaline Environmentally Sound Coil Cleaner Application
Equipment
•2
1/2gallon garden sprayer
• water rinse with low velocity spray nozzle
Totaline Environmentally Sound Coil Cleaner Application
Instructions
1. Proper eye protection such as safety glasses, gloves and
protective clothing are recommended during mixing and
application.
2. Remove all surface loaded fibers and dirt with a vacuum
cleaner as described above.
3. Thoroughly wet finned surfaces with clean water and a
low velocity garden hose, being careful not to bend fins.
4. Mix Totaline environmentally sound coil cleaner in a
21/2gallon garden sprayer according to the instructions
included with the cleaner. The optimum solution tempera-
ture is 100°F (38°C).
NOTE: Do NOT use water in excess of 130°F (54°C), as the enzy-
matic activity will be destroyed.
5. Thoroughly apply Totaline environmentally sound coil
cleaner solution to all coil surfaces including finned area,
tube sheets and coil headers.
WARNING
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this warning could cause personal injury,
death and/or equipment damage.
This system uses R-410A refrigerant, which has higher
pressures than R-22 and other refrigerants. No other refrig-
erant may be used in this system. Gage set, hoses, and re-
covery system must be designed to handle R-410A refriger-
ant. If unsure about equipment, consult the equipment man-
ufacturer.
CAUTION
UNIT DAMAGE HAZARD
Failure to follow this caution may result in accelerated cor-
rosion of unit parts.
Harsh chemicals, household bleach or acid or basic clean-
ers should not be used to clean outdoor or indoor coils of
any kind. These cleaners can be very difficult to rinse out of
the coil and can accelerate corrosion at the fin/tube inter-
face where dissimilar materials are in contact. If there is
dirt below the surface of the coil, use the environmentally
balanced coil cleaner.
CAUTION
UNIT DAMAGE HAZARD
Failure to follow this caution may result in reduced unit
performance or unit shutdown.
High velocity water from a pressure washer, garden hose,
or compressed air should never be used to clean a coil. The
force of the water or air jet will bend the fin edges and in-
crease airside pressure drop.

6
6. Hold garden sprayer nozzle close to finned areas and apply
cleaner with a vertical, up-and-down motion. Avoid spraying
in horizontal pattern to minimize potential for fin damage.
7. Ensure cleaner thoroughly penetrates deep into finned
areas.
8. Interior and exterior finned areas must be thoroughly
cleaned.
9. Finned surfaces should remain wet with cleaning solution
for 10 minutes.
10. Ensure surfaces are not allowed to dry before rinsing.
Reapply cleaner as needed to ensure 10-minute saturation
is achieved.
11. Thoroughly rinse all surfaces with low velocity clean
water using downward rinsing motion of water spray noz-
zle. Protect fins from damage from the spray nozzle.
Evaporator Coil Metering Devices
These systems use thermal expansion valves (TXV).
Refrigerant System Pressure Access Ports
There are two access ports in each system - on the suction tube
near the compressor and on the discharge tube near the com-
pressor. These are brass fittings with black plastic caps. The
hose connection fittings are standard 1/4-in. SAE Male Flare
couplings.
The brass fittings are two-piece High Flow valves, with a re-
ceptacle base brazed to the tubing and an integral spring-closed
check valve core screwed into the base. (See Fig. 8.) This
Schrader valve is permanently assembled into the core body
and cannot be serviced separately. Replace the entire core body
if necessary. Service tools are available from RCD (P920-
0010) that allow the replacement of the Schrader valve core
without having to recover the entire system refrigerant charge.
Apply compressor refrigerant oil to the Schrader valve core’s
bottom O-ring. Install the fitting body with 96 ±10 in. lbs of
torque; do not over-tighten.
NOTE: The High Flow valve has a black plastic cap with a rubber
O-ring located inside the cap. This rubber O-ring must be in place
in the cap to prevent refrigerant leaks.
EXAMPLE:
Model 50LC*D26
Coil-Leaving Temperature . . . . . . . . . . . . . 85°F (29°C)
Discharge Pressure . . . . . . . . . . . . . . 340 psig (2344 kPa)
PURON®(R-410A) REFRIGERANT
This unit is designed for use with Puron (R-410A) refrigerant.
Do not use any other refrigerant in this system.
Puron (R-410A) refrigerant is provided in pink (rose) colored
cylinders. These cylinders are available with and without dip
tubes; cylinders with dip tubes will have a label indicating this
feature. For a cylinder with a dip tube, place the cylinder in the
upright position (access valve at the top) when adding liquid
refrigerant for charging. For a cylinder without a dip tube, in-
vert the cylinder (access valve on the bottom) when adding liq-
uid refrigerant.
Because Puron (R-410A) refrigerant is a blend, it is strongly
recommended that refrigerant always be removed from the cyl-
inder as a liquid. Admit liquid refrigerant into the system in the
discharge line when breaking refrigerant system vacuum while
the compressor is OFF. Only add refrigerant (liquid) into the
suction line while the compressor is operating. If adding refrig-
erant into the suction line, use a commercial metering/expan-
sion device at the gage manifold. Remove liquid from the cyl-
inder, pass it through the metering device at the gage set and
then pass it into the suction line as a vapor. Do not remove
Puron (R-410A) refrigerant from the cylinder as a vapor.
Refrigerant Charge
Amount of refrigerant charge is listed on the unit’s nameplate.
Refer to Carrier GTAC2-5 Charging, Recovery, Recycling and
Reclamation training manual and the following procedures.
Unit panels must be in place when unit is operating during the
charging procedure.
NO CHARGE
Use standard evacuating techniques. Evacuate system down to
500 microns and let set for 10 minutes to determine if system
has a refrigerant leak. If evacuation level raises to
1100 microns and stabilizes, the system has moisture in it and
should be dehydrated per GTAC2-5 recommends.
If system continues to rise above 1100 microns, the system has
a leak and should be pressurized and leak tested using appro-
priate techniques as explained in GTAC2-5. After evacuating
system, weigh in the specified amount of refrigerant as listed
on the unit rating plate.
Fig. 8 — CoreMax1Access Port Assembly
1. CoreMax is a registered trademark of Fastest, Inc.
5/8” HEX 0.47
30°
0.596
1/2-20 UNF RH
1/2” HEX
45°
WASHER
O-RING
7/16-20 UNF RH
DEPRESSOR PER AHRI 720
+.01/-.035
FROM FACE OF BODY
Thissurface providesametal to metal seal when
torqued into the seat. Appropriate handling is
required to not scratch or dent the surface.
SEAT CORE
(Part No. EC39EZ067)

7
LOW-CHARGE COOLING
Using Cooling Charging Charts (Fig. 10-14.), vary refrigerant
until the conditions of the appropriate chart are met. Note the
charging charts are different from the type normally used.
Charts are based on charging the units to the correct subcooling
for the various operating conditions. Accurate pressure gage
and temperature sensing device are required. Connect the pres-
sure gage to the service port on the discharge line. Mount the
temperature sensing device on the liquid line leaving the con-
denser coil and insulate it so that outdoor ambient temperature
does not affect the reading. Indoor-air cfm must be within the
normal operating range of the unit.
TO USE COOLING CHARGING CHARTS
Select the appropriate unit charging chart from Fig. 10-14.
Take the liquid-line temperature and read the discharge pres-
sure gage. Refer to chart to determine what liquid-line tem-
perature should be. If liquid-line temperature is high, add re-
frigerant. If liquid-line temperature is low, carefully recover
some of the charge. Recheck the discharge pressure as charge
is adjusted.
Evacuation
Proper evacuation of the system will remove non-condensables
and ensure a tight, dry system before charging. Evacuate from
both high and low side ports. Never use the system compressor
as a vacuum pump. Refrigerant tubes and indoor coil should be
evacuated to 500 microns. Always break a vacuum with dry ni-
trogen. The two possible methods are the deep vacuum method
and the triple evacuation method.
DEEP VACUUM METHOD
The deep vacuum method requires a vacuum pump capable of
pulling a minimum vacuum of 500 microns and a vacuum gage
capable of accurately measuring this vacuum depth. The deep
vacuum method is the most positive way of assuring a system
is free of air and liquid water. (See Fig. 9.)
Fig. 9 — Deep Vacuum Graph
TRIPLE EVACUATION METHOD
The triple evacuation method should only be used when vacu-
um pump is capable of pumping down to 28-in. of mercury and
system does not contain any liquid water.
Proceed as follows:
1. Pump system down to 28-in. of mercury and allow pump
to continue operating for an additional 15 minutes.
2. Close service valves and shut off vacuum pump.
3. Connect a nitrogen cylinder and regulator to system and
open until system pressure is 2 psig.
4. Close service valve and allow system to stand for 1 hour.
During this time, dry nitrogen will be able to diffuse
throughout the system, absorbing moisture.
5. Repeat this procedure. System will then contain minimal
amounts of contaminants and water vapor.
LEAK IN
SYSTEM
VACUUM
TIGHT
TOO WET
TIGHT
DRY SYSTEM
01234567
MINUTES
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
MICRONS

8
Fig. 10 — Cooling Charging Chart (50LC14)
1050 1350 1650 1950 2250 2550 2850 3150 3450 3750 4050 4350
-6
0
6
12
18
24
30
36
42
48
54
60
20
40
60
80
100
120
140
150 200 250 300 350 400 450 500 550 600 650
seergeD[,erutarepmeTgnivaeL
lioCroodtuO°F/°C]
Compressor Discharge Pressure, [psig / Kpa]
50LC500756
REV-B
Remove charge if below the curve
Standard Unit
Standard Unit with
Humidi-MiZer
For Standard Units: Must run both compressors and OFM at high speed
For Humidi-MiZer Units: Must run Sub-Cooling Mode
12.5 Ton R-410A CHARGING CHART
Add charge if above curve

9
Fig. 11 — Cooling Charging Charts (50LC17)
1050 1350 1650 1950 2250 2550 2850 3150 3450 3750 4050 4350
-6
0
6
12
18
24
30
36
42
48
54
60
20
40
60
80
100
120
140
150 200 250 300 350 400 450 500 550 600 650
seergeD[,erutarepmeTgnivaeLlioCroodtuO°F/°C]
Compressor Discharge Pressure, [psig / Kpa]
50LC500757
REV-B
Standard Unit
Standard Unit with
Humidi-MiZer
For Standard Units: Must run both compressors and OFM at high speed
For Humidi-MiZer Units: Must run Sub-Cooling Mode
Remove charge if below the curve
15 Ton R-410A CHARGING CHART
Add charge if above curve

10
Fig. 12 — Cooling Charging Charts (50LC20)
1050 1350 1650 1950 2250 2550 2850 3150 3450 3750 4050 4350
-6
0
6
12
18
24
30
36
42
48
54
60
20
40
60
80
100
120
140
150 200 250 300 350 400 450 500 550 600 650
Outdoor Coil Leaving Temperature, [Degrees °F/°C]
Compressor Discharge Pressure, [psig / Kpa]
50LC500758 REV-B
Remove charge if below the curve
Standard Unit
Standard Unit
w/ Humidi-MiZer®
For Standard Units: Must run both compressors and OFM at high speed
For Humidi-MiZer Units: Must run Sub-Cooling Mode
17.5 Ton R-410A CHARGING CHART
Add charge if above curve