Carrier 50LC 07 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. 04-53500166-01 Printed in U.S.A. Form 50LC-7-12-03SM Pg 1 1-2020 Replaces: 50LC-7-12-02SM
Service and Maintenance Instructions
TABLE OF CONTENTS
SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . 1
UNIT ARRANGEMENT AND ACCESS. . . . . . . . . . . . . 2
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Routine Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Seasonal Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . 2
SUPPLY FAN (BLOWER) SECTION . . . . . . . . . . . . . . 3
Supply Fan (Belt-Drive) . . . . . . . . . . . . . . . . . . . . . . . . 3
COOLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Evaporator Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Coil Maintenance and Cleaning Recommendation. . 5
Refrigerant System Pressure Access Ports . . . . . . . 6
PURON®(R-410A) REFRIGERANT. . . . . . . . . . . . . . . 7
Refrigerant Charge. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Compressors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Filter Drier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Condenser-Fan Location. . . . . . . . . . . . . . . . . . . . . . . 7
Troubleshooting Cooling System. . . . . . . . . . . . . . . . 8
COOLING CHARGING CHARTS . . . . . . . . . . . . . . . . . 9
CONVENIENCE OUTLETS . . . . . . . . . . . . . . . . . . . . . 12
Weatherproof Cover Installation. . . . . . . . . . . . . . . . 13
Types of Convenience Outlets . . . . . . . . . . . . . . . . . 13
SMOKE DETECTORS. . . . . . . . . . . . . . . . . . . . . . . . . 14
System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Smoke Detector Locations . . . . . . . . . . . . . . . . . . . . 14
Completing Installation of Return Air Smoke
Sensor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
FIOP Smoke Detector Wiring and Response. . . . . . 16
Sensor and Controller Tests . . . . . . . . . . . . . . . . . . . 17
Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Resetting Alarm and Trouble Condition Trips . . . . 19
Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
PROTECTIVE DEVICES . . . . . . . . . . . . . . . . . . . . . . . 19
Compressor Protection . . . . . . . . . . . . . . . . . . . . . . . 19
Supply (Indoor) Fan Motor Protection . . . . . . . . . . . 20
Condenser Fan Motor Protection . . . . . . . . . . . . . . . 20
Control Circuit, 24-v. . . . . . . . . . . . . . . . . . . . . . . . . . 20
ELECTRIC HEATERS . . . . . . . . . . . . . . . . . . . . . . . . . 20
Single Point Boxes and Supplementary Fuses. . . . 21
Safety Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Low-Voltage Control Connections . . . . . . . . . . . . . . 21
PRE-START-UP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
START-UP, GENERAL . . . . . . . . . . . . . . . . . . . . . . . . 23
Unit Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Return-Air Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Outdoor-Air Inlet Screens . . . . . . . . . . . . . . . . . . . . . 23
Compressor Mounting . . . . . . . . . . . . . . . . . . . . . . . .23
Internal Wiring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Refrigerant Service Ports. . . . . . . . . . . . . . . . . . . . . .23
Compressor Rotation . . . . . . . . . . . . . . . . . . . . . . . . .23
Cooling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Heating. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
To Shut Off Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Ventilation (Continuous Fan). . . . . . . . . . . . . . . . . . . 23
Electrical Connections . . . . . . . . . . . . . . . . . . . . . . . .23
RTU Open Control System. . . . . . . . . . . . . . . . . . . . .25
SystemVu™ (Factory Option) . . . . . . . . . . . . . . . . . .25
Integrated Staging Control (ISC) Board . . . . . . . . . .26
EconoMi$er® X (Factory Option) . . . . . . . . . . . . . . .28
Staged Air Volume (SAV™) with Variable Frequency
Drive. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
Multi-Speed VFD Display Kit (Field-Installed
Option). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
FASTENER TORQUE VALUES. . . . . . . . . . . . . . . . . .54
APPENDIX A —MODEL NUMBER
NOMENCLATURE . . . . . . . . . . . . . . . . . . . . . . . . . .55
APPENDIX B —PHYSICAL DATA . . . . . . . . . . . . . . .56
APPENDIX C —FAN PERFORMANCE . . . . . . . . . . .58
APPENDIX D —WIRING DIAGRAMS . . . . . . . . . . . .67
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 litera-
ture, tags and labels attached to the unit, and other safety precau-
tions that may apply.
Follow all safety codes, including ANSI (American National Stan-
dards 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 in-
structions 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.
WeatherExpert® 50LC**07-12
Single Package Rooftop
Electric Cooling with Optional Electric Heat
with Puron®(R-410A) Refrigerant

2
UNIT ARRANGEMENT AND ACCESS
General
Figures 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 econ-
omizer, it will also have an outside air screen. If a manual 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.
WARNING
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal injury or
death.
Before performing service or maintenance operations on unit,
LOCKOUT/TAGOUT the main power switch to unit. Electri-
cal shock and rotating equipment could cause severe injury.
WARNING
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal injury or
death.
Units with convenience outlet circuits may use multiple
disconnects. Check convenience outlet for power status before
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
OUTDOOR-AIR OPENING AND
INDOOR COIL ACCESS PANEL
COMPRESSOR
ACCESS PANEL (04-07 only)
BLOWER
ACCESS
PANEL
CONTROL BOX
COMPRESSOR

3
RETURN AIR FILTERS
Return air filters are disposable fiberglass media type. Access to
the filters is through the small lift-out panel located on the rear
side of the unit, above the evaporator/return air access panel. (See
Fig. 1.)
To remove the filters:
1. Grasp the bottom flange of the upper panel.
2. Lift up and swing the bottom out until the panel disengages
and pulls out.
3. Reach inside and extract the filters from the filter rack.
4. Replace these filters as required with similar replacement fil-
ters of same size.
To re-install the access panel:
1. Slide the top of the panel up under the unit top panel.
2. Slide the bottom into the side channels.
3. Push the bottom flange down until it contacts the top of the
lower panel (or economizer top).
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 washing with hot low-pressure wa-
ter and soft detergent and replace all screens before restarting the
unit. Observe the flow direction arrows on the side of each filter
frame.
ECONOMIZER INLET AIR SCREEN
This air screen is retained by spring clips under the top edge of the
hood. (See Fig. 3.)
To remove the filter, open the spring clips. Re-install the filter by
placing the frame in its track, then closing the spring clips.
Fig. 3 — Filter Installation
MANUAL OUTSIDE AIR HOOD SCREEN
This inlet screen is secured by a retainer angle across the top edge
of the hood. (See Fig. 4.)
To remove the screen, loosen the screws in the top retainer and
slip the retainer up until the filter can be removed. Re-install by
placing the frame in its track, rotating the retainer back down
and tighten all screws.
Fig. 4 — Screens Installed on Outdoor-Air Hood
SUPPLY FAN (BLOWER) SECTION
Supply Fan (Belt-Drive)
The supply fan system consists of a forward-curved centrifugal
blower wheel on a solid shaft with two concentric type bearings,
one on each side of the blower housing. A fixed-pitch driven pul-
ley is attached to the fan shaft and an adjustable-pitch driver pulley
is on the motor. The pulleys are connected using a “V” type belt.
(See Fig. 5.)
Fig. 5 — 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 surfaces.
Check belt tension by using a spring-force tool (such as Brown-
ing’s Part Number “Belt Tension Checker” or equivalent tool);
tension should be 6 lb at a 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.
IMPORTANT: DO NOT OPERATE THE UNIT WITHOUT
THESE FILTERS!
17 1/4”
DIVIDER
BAROMETRIC
RELIEF
CLEANABLE
ALUMINUM
FILTER FILTER
HOOD
FILTER
CLIP
OUTSIDE
AIR
CAUTION
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could cause personal injury or
death.
Before performing service or maintenance operations on the
fan system, shut off all unit power and lockout/tag-out the unit
disconnect switch. DO NOT reach into the fan section with
power still applied to unit.
SCREWS

4
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 belt tension by loosening the motor mounting plate front
bolts and rear bolt and sliding the plate toward the fan (to reduce
tension) or away from fan (to increase tension). Ensure the blower
shaft and the motor shaft are parallel to each other (pulleys
aligned). Tighten all bolts when finished.
To replace the belt:
1. Use a belt with same section type or similar size. Do not sub-
stitute 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. Push the motor and its mounting plate towards the blower
housing as close as possible to reduce the center distance
between fan shaft and motor shaft.
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 pul-
leys and then sliding the motor and plate away from the fan
housing until proper tension is achieved.
6. Check the alignment of the pulleys, adjust if necessary.
7. Tighten all 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 servicer
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 realignment 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 surfaces 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.
2. Loosen belt by loosening fan motor mounting nuts. (See
Fig. 5.)
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 specified.
5. Set movable flange at nearest keyway of pulley hub and
tighten setscrew to torque specifications.
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 locking
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
are in contact with the motor’s painted base. Tighten motor
mounting bolts to 120 ± 12 in.-lb.
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 (typically the
motor pulley in these units). Do not install a replacement motor
pulley with a smaller pitch diameter than provided on the original
factory pulley. Change fan wheel speed by changing the fan pulley
(larger pitch diameter to reduce wheel speed, smaller pitch diame-
ter 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 determine
new motor loading (bhp). Use the fan performance tables in
Appendix C or use the Packaged Rooftop Builder software pro-
gram. Confirm that the motor in this unit is capable of operating at
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
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.
COOLING
Evaporator Coil
The evaporator coil is traditional round-tube, plate-fin technology.
Tube and fin construction is of various optional materials and
coatings (see Appendix A). Coils are multiple-row.
Coil Maintenance and Cleaning Recommendation
Routine cleaning of coil surfaces is essential to maintain proper
operation of the unit. Elimination of contamination and removal of
harmful residues will greatly increase the life of the coil and ex-
tend 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-metallic
bristle brush may be used. In either case, the tool should be ap-
plied in the direction of the fins. Coil surfaces can be easily dam-
aged (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 ap-
plied in coastal or industrial environments. However, it is very im-
portant that the water rinse is made with very low velocity water
stream to avoid damaging the fin edges. Monthly cleaning as de-
scribed below is recommended.
ROUTINE CLEANING OF EVAPORATOR COIL SURFACES
Monthly cleaning with Totaline® environmentally balanced coil
cleaner is essential to extend the life of coils. This cleaner is avail-
able from Carrier Replacement parts division as part number
P902-0301 for a 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 du-
rability 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 biodegrad-
able agent that will not harm coil or surrounding components such
as electrical wiring, painted metal surfaces, or insulation. Use of
non-recommended coil cleaners is strongly discouraged since coil
and unit durability could be affected.
Totaline Environmentally Balanced Coil Cleaner Application
Equipment
• 21/2 gallon garden sprayer
• Water rinse with low velocity spray nozzle
Totaline Environmentally Balanced Coil Cleaner Application
Instructions
1. Proper eye protection such as safety glasses is 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 balanced coil cleaner in a
21/2 gallon garden sprayer according to the instructions
included with the cleaner. The optimum solution temperature
is 100°F (38°C).
NOTE: Do NOT USE water in excess of 130°F (54°C), as the en-
zymatic activity will be destroyed.
5. Thoroughly apply Totaline environmentally balanced coil
cleaner solution to all coil surfaces including finned area, tube
sheets and coil headers.
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. Reap-
ply cleaner as needed to ensure 10 minute saturation is
achieved.
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 pres-
sures than R-22 and other refrigerants. No other refrigerant
may be used in this system. Gage set, hoses, and recovery sys-
tem must be designed to handle R-410A refrigerant. If unsure
about equipment, consult the equipment manufacturer.
CAUTION
UNIT DAMAGE HAZARD
Failure to follow this caution may result in accelerated
corrosion of unit parts.
Harsh chemicals, household bleach or acid or basic cleaners
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 interface 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 perfor-
mance 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 increase air-
side pressure drop.

6
11. Thoroughly rinse all surfaces with low velocity clean water
using downward rinsing motion of water spray nozzle. Pro-
tect fins from damage from the spray nozzle.
EVAPORATOR COIL METERING DEVICES
These units 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 compres-
sor. These are brass fittings with black plastic caps. The hose con-
nection fittings are standard 1/4-in. SAE Male Flare couplings.
The brass fittings are two-piece High Flow valves, with a recepta-
cle base brazed to the tubing and an integral spring-closed check
valve core screwed into the base. (See Fig. 8.) This check valve is
permanently assembled into this core body and cannot be serviced
separately. Replace the entire core body if necessary. Service tools
are available from RCD that allow the replacement of the check
valve core without having to recover the entire system refrigerant
charge. Apply compressor refrigerant oil to the check valve core’s
bottom O-ring. Install the fitting body with 96 ± 10 in-lb of torque;
do not overtighten.
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
This surface provides a metal 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
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 cyl-
inders. 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 po-
sition (access valve at the top) when removing liquid refrigerant
for charging. For a cylinder without a dip tube, invert the cylinder
(access valve on the bottom) when removing liquid refrigerant.
Because Puron (R-410A) refrigerant is a blend, it is strongly rec-
ommended that refrigerant always be removed from the cylinder
as a liquid. Admit liquid refrigerant into the system in the dis-
charge line. If adding refrigerant into the suction line, use a com-
mercial metering/expansion device at the gage manifold. Remove
liquid from the cylinder, pass it through the metering device at the
gage set and then pass it into the suction line as a vapor. Do not re-
move Puron (R-410A) refrigerant from the cylinder as a vapor.
Refrigerant Charge
Amount of refrigerant charge is listed on the unit’s nameplate. Re-
fer to Carrier GTAC2-5 Charging, Recovery, Recycling and Rec-
lamation 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. After evacuating system,
weigh in the specified amount of refrigerant.
LOW-CHARGE COOLING
Using Cooling Charging Charts (Fig. 10-13), 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 op-
erating conditions. Accurate pressure gage and temperature sens-
ing device are required. Connect the pressure gage to the service
port on the discharge line. Mount the temperature sensing device
on the liquid line leaving the condenser 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.
50LC*D07-14 CHARGING
To prepare the unit for charge adjustment:
Disable/bypass all head pressure controls. Start/run both compres-
sors. On sizes 08 and 12, ensure both condenser fans are running.
TO USE COOLING CHARGING CHARTS
Select the appropriate unit charging chart from Fig. 10-13.
Take the liquid-line temperature and read the discharge pressure
gage. Refer to chart to determine what liquid-line temperature
should be. If liquid-line temperature is high, add refrigerant. If liq-
uid-line temperature is low, carefully recover some of the charge.
Recheck the discharge pressure as charge is adjusted.
EXAMPLE:
Model 50LC*D14
Circuit 1:
Outdoor Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . 85°F (29°C)
Discharge Pressure . . . . . . . . . . . . . . . . . . . . . 350 psig (2413 kPa)
Compressors
LUBRICATION
Compressors are charged with the correct amount of oil at the
factory.
REPLACING COMPRESSOR
The compressor used with Puron refrigerant contains a POE oil.
This oil has a high affinity for moisture. Do not remove the com-
pressor’s tube plugs until ready to insert the unit suction and dis-
charge tube ends. Compressor mounting bolt torque is 65 to
75 in.-lb (7.3 to 8.5 Nm).
COMPRESSOR ROTATION
On 3-phase units with scroll compressors, it is important to be cer-
tain 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 discharge pressure
should rise, as is normal on any start-up.
NOTE: If the suction pressure does not drop and the discharge
pressure does not rise to normal levels:
1. Note that the evaporator fan is probably also rotating in the
wrong direction.
2. Turn off power to the unit.
3. Reverse any two of the unit power leads.
4. Reapply power to the compressor.
The suction and discharge pressure levels should now move to
their normal start-up levels.
NOTE: When the compressor is rotating in the wrong direction,
the unit makes an elevated level of noise and does not provide
cooling.
Filter Drier
Replace whenever refrigerant system is exposed to atmosphere.
Only use factory specified liquid-line filter driers with working
pressures no less than 650 psig. Do not install a suction-line filter
drier in liquid line. A liquid-line filter drier designed for use with
Puron refrigerant is required on every unit.
Condenser-Fan Location
See Fig. 9.
1. Shut off unit power supply. Install lockout tag.
2. Remove condenser-fan assembly (grille, motor, and fan).
3. Loosen fan hub setscrews.
4. Adjust fan height as shown in Fig. 9.
5. Tighten setscrews to 84 in-lb (9.5 Nm).
6. Replace condenser-fan assembly.
CAUTION
UNIT DAMAGE HAZARD
Failure to follow this caution may result in damage to
components.
The compressor is in a R-410A refrigerant system and uses a
polyolester (POE) oil. This oil is extremely hygroscopic,
meaning it absorbs water readily. POE oils can absorb
15 times as much water as other oils designed for HCFC and
CFC refrigerants. Avoid exposure of the oil to the atmosphere.

8
Fig. 9 — Condenser Fan Adjustment
Troubleshooting Cooling System
Refer to Table 1 for additional troubleshooting topics.
CONDUIT
0.14 in. + 0.0 / -0.03
Table 1 — Cooling Service Analysis
PROBLEM CAUSE REMEDY
Compressor and Condenser
Fan Will Not Start
Power failure. Call power company.
Fuse blown or circuit breaker tripped. Replace fuse or reset circuit breaker.
Defective thermostat, contactor, transformer, or control relay. Replace component.
Insufficient line voltage. Determine cause and correct.
Incorrect or faulty wiring. Check wiring diagram and rewire correctly.
Thermostat setting too high. Lower thermostat setting below room temperature.
Compressor Will Not Start
But Condenser Fan Runs
Faulty wiring or loose connections in compressor circuit. Check wiring and repair or replace.
Compressor motor burned out, seized, or internal overload
open. Determine cause. Replace compressor.
Defective run/start capacitor, overload, start relay. Determine cause and replace.
One leg of three-phase power dead. Replace fuse or reset circuit breaker. Determine
cause.
Compressor Cycles (other
than normally satisfying
thermostat)
Refrigerant overcharge or undercharge. Recover refrigerant, evacuate system, and recharge
to nameplate.
Defective compressor. Replace and determine cause.
Insufficient line voltage. Determine cause and correct.
Blocked condenser. Determine cause and correct.
Defective run/start capacitor, overload, or start relay. Determine cause and replace.
Defective thermostat. Replace thermostat.
Faulty condenser-fan motor or capacitor. Replace.
Restriction in refrigerant system. Locate restriction and remove.
Compressor Operates
Continuously
Dirty air filter. Replace filter.
Unit undersized for load. Decrease load or increase unit size.
Thermostat set too low. Reset thermostat.
Low refrigerant charge. Locate leak; repair and recharge.
Leaking valves in compressor. Replace compressor.
Air in system. Recover refrigerant, evacuate system, and
recharge.
Condenser coil dirty or restricted. Clean coil or remove restriction.
Excessive Head Pressure
Dirty air filter. Replace filter.
Dirty condenser coil. Clean coil.
Refrigerant overcharged. Recover excess refrigerant.
Air in system. Recover refrigerant, evacuate system, and
recharge.
Condenser air restricted or air short-cycling. Determine cause and correct.
Head Pressure Too Low
Low refrigerant charge. Check for leaks; repair and recharge.
Compressor valves leaking. Replace compressor.
Restriction in liquid tube. Remove restriction.
Excessive Suction Pressure
High heat load. Check for source and eliminate.
Compressor valves leaking. Replace compressor.
Refrigerant overcharged. Recover excess refrigerant.
Suction Pressure Too Low
Dirty air filter. Replace filter.
Low refrigerant charge. Check for leaks; repair and recharge.
Metering device or low side restricted. Remove source of restriction.
Insufficient evaporator airflow. Increase air quantity. Check filter and replace if
necessary.
Temperature too low in conditioned area. Reset thermostat.
Outdoor ambient below 25°F. Install low-ambient kit.
Evaporator Fan Will Not
Shut Off Time off delay not finished. Wait for 30-second off delay.
Compressor Makes
Excessive Noise Compressor rotating in wrong direction. Reverse the 3-phase power leads.

9
COOLING CHARGING CHARTS
Fig. 10 — 50LC**07 Cooling Charging Chart
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]
48LC500412 Re v- A
Rem ove charge if below the curve
Standard Unit
Standard Unit w /
Hum id i- M iZer
6 Ton R-410A CHARGING CHART
For Standard Units: Must run both compressors and OFM at high speed
For Humidi-MiZer Units: Must run Sub-Cooling Mode
Add charge if above the curve

10
Fig. 11 — 50LC**08 Cooling Charging Chart
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]
48LC500413 REV - C
Standard Unit
Standard Unit w /
Hum id i- M iZer
For Standard Units: Must run both compressors and OFM at high speed
For Humidi-MiZer Units: Must run Sub-Cooling Mode
7.5 Ton R-410A CHARGING CHART
Add charge if above curve
Remove charge if below curve

11
Fig. 12 — 50LC**09 Cooling Charging Chart
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]
48LC500414 REV - B
Rem ove charge if below the curve
Standard Unit
Standard Unit w /
Hum id i- M iZer
For Standard Units: Must run both compressors and OFM at high speed
For Humidi-MiZer Units: Must run Sub-Cooling Mode
8.5 Ton R-410A CHARGING CHART
Add charge if above the curve

12
Fig. 13 — 50LC**12 Cooling Charging Chart
CONVENIENCE OUTLETS
Two types of convenience outlets are offered on 50LC models:
Non-powered and unit-powered. Both types provide a 125-volt
GFCI (ground-fault circuit-interrupter) duplex receptacle rated at
15-A behind a hinged waterproof access cover, located on the end
panel of the unit. (See Fig. 14.)
Fig. 14 — Convenience Outlet Location
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]
48LC500415 REV - B
Re m o ve char ge if be lo w t h e cu rve
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
10 Ton R-410A CHARGING CHART
Add charge if above the curve
WARNING
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal injury or
death.
Units with convenience outlet circuits may use multiple
disconnects. Check convenience outlet for power status before
opening unit for service. Locate its disconnect switch, if
appropriate, and open it. Lock-out and tag-out this switch, if
necessary.
CONVENIENCE
OUTLET GFCI
PWD-CO FUSE
SWITCH
PWD-CO TRANSFORMER
CONTROL BOX
ACCESS PANEL

13
Weatherproof Cover Installation
A weatherproof while-in-use cover for the factory-installed conve-
nience outlets is now required by UL standards. This cover cannot
be factory-mounted due to its depth. It must be installed at unit in-
stallation. For shipment, the convenience outlet is covered with a
blank cover plate.
The weatherproof cover kit is shipped in the unit’s control box.
The kit includes the hinged cover, a backing plate and gasket.
1. Remove the blank cover plate at the convenience outlet. Dis-
card the blank cover.
2. Loosen the two screws at the GFCI duplex outlet, until
approximately 1/2-in. (13 mm) under screw heads are
exposed.
3. Press the gasket over the screw heads.
4. Slip the backing plate over the screw heads at the keyhole
slots and align with the gasket. Tighten the two screws until
snug (do not over-tighten).
5. Mount the weatherproof cover to the backing plate as shown
in Fig. 15.
6. Remove two slot fillers in the bottom of the cover to permit
service tool cords to exit the cover.
7. Check for full closing and latching.
Fig. 15 — Weatherproof Cover Installation
Types of Convenience Outlets
NON-POWERED TYPE
This type requires the field installation of a general-purpose 125-v
15-A circuit powered from a source elsewhere in the building. Ob-
serve national and local codes when selecting wire size, fuse or
breaker requirements and disconnect switch size and location.
Route 125-v power supply conductors into the bottom of the utili-
ty box containing the duplex receptacle.
UNIT-POWERED TYPE
A unit-mounted transformer is factory-installed to stepdown the
main power supply voltage to the unit to 115-v at the duplex re-
ceptacle. This option also includes a manual switch with fuse, lo-
cated in a utility box and mounted on a bracket behind the conve-
nience outlet; access is through the unit’s control box access panel.
(See Fig. 14.)
The primary leads to the convenience outlet transformer are not
factory-connected. Selection of primary power source is a custom-
er option. If local codes permit, the transformer primary leads can
be connected at the line-side terminals on a unit-mounted non-
fused disconnect or circuit-breaker switch; this will provide ser-
vice power to the unit when the unit disconnect switch or circuit-
breaker is open. Other connection methods will result in the con-
venience outlet circuit being de-energized when the unit discon-
nect or circuit-breaker is open. (See Fig. 16.)
Fig. 16 — Powered Convenience Outlet Wiring
Duty Cycle
The unit-powered convenience outlet has a duty cycle limitation.
The transformer is intended to provide power on an intermittent
basis for service tools, lamps, etc; it is not intended to provide
15 amps loading for continuous duty loads (such as electric heat-
ers for overnight use). Observe a 50% limit on circuit loading
above 8 amps (i.e., limit loads exceeding 8 amps to 30 minutes of
operation every hour).
Maintenance
Periodically test the GFCI receptacle by pressing the TEST button
on the face of the receptacle. This should cause the internal circuit
of the receptacle to trip and open the receptacle. Check for proper
grounding wires and power line phasing if the GFCI receptacle
does not trip as required. Press the RESET button to clear the
tripped condition.
Fuse On Powered Type
The factory fuse is a Bussman1 “Fusetron” T-15, non-renewable
screw-in (Edison base) type plug fuse.
USING UNIT-MOUNTED CONVENIENCE OUTLETS
Units with unit-mounted convenience outlet circuits will often re-
quire that two disconnects be opened to de-energize all power to
the unit. Treat all units as electrically energized until the conve-
nience outlet power is also checked and de-energization is con-
firmed. Observe National Electrical Code Article 210, Branch Cir-
cuits, for use of convenience outlets.
IMPORTANT: DISCONNECT ALL POWER TO UNIT AND
CONVENIENCE OUTLET.
TOP
TOP
TOP
WET LOCATIONS
WE T LOC ATIONS
COVER - WHILE-IN-USE
WEATHERPROOF
BASEPLATE FOR
GFCI RECEPTACLE
GASKET
GFCI RECEPTACLE
NOT INCLUDED
1. Bussmann and Fusetron are trademarks of Cooper Technologies
Company.
UNIT
VOLTAGE
CONNECT
AS
PRIMARY
CONNECTIONS
TRANSFORMER
TERMINALS
208, 230 240 L1: RED +YEL
L2: BLU + GRA
H1 + H3
H2 + H4
460 480
L1: RED
Splice BLU + YEL
L2: GRA
H1
H2 + H3
H4
575 600 L1: RED
L2: GRA
H1
H2

14
SMOKE DETECTORS
Smoke detectors are available as factory-installed options on
50LC models. Smoke detectors may be specified for supply air
only, for return air without or with economizer, or in combination
of supply air and return air. Return-air smoke detectors are ar-
ranged for vertical return configurations only. All components
necessary for operation are factory-provided and mounted. The
unit is factory-configured for immediate smoke detector shutdown
operation; additional wiring or modifications to unit terminal
board may be necessary to complete the unit and smoke detector
configuration to meet project requirements.
System
The smoke detector system consists of a four-wire controller and
one or two sensors. Its primary function is to shut down the roof-
top unit in order to prevent smoke from circulating throughout the
building. It is not to be used as a life saving device.
Controller
The controller includes a controller housing, a printed circuit
board, and a clear plastic cover. (See Fig. 17.) The controller can
be connected to one or two compatible duct smoke sensors. The
clear plastic cover is secured to the housing with a single captive
screw for easy access to the wiring terminals. The controller has
three LEDs (for Power, Trouble and Alarm) and a manual test/
reset button (on the cover face).
Fig. 17 — Controller Assembly
Sensor
The sensor includes a plastic housing, a printed circuit board, a
clear plastic cover, a sampling tube inlet and an exhaust tube. (See
Fig. 18.) The sampling tube (when used) and exhaust tube are at-
tached during installation. The sampling tube varies in length de-
pending on the size of the rooftop unit. The clear plastic cover per-
mits visual inspections without having to disassemble the sensor.
The cover attaches to the sensor housing using four captive screws
and forms an airtight chamber around the sensing electronics.
Each sensor includes a harness with an RJ45 terminal for connect-
ing to the controller. Each sensor has four LEDs (Power, Trouble,
Alarm and Dirty) and a manual test/reset button (on the left-side of
the housing).
Air is introduced to the duct smoke detector sensor’s sensing
chamber through a sampling tube that extends into the HVAC duct
and is directed back into the ventilation system through a (shorter)
exhaust tube. The difference in air pressure between the two tubes
pulls the sampled air through the sensing chamber. When a suffi-
cient amount of smoke is detected in the sensing chamber, the sen-
sor signals an alarm state and the controller automatically takes
the appropriate action to shut down fans and blowers, change over
air handling systems, notify the fire alarm control panel, etc.
The sensor uses a process called differential sensing to prevent
gradual environmental changes from triggering false alarms. A
rapid change in environmental conditions, such as smoke from a
fire, causes the sensor to signal an alarm state, but dust and debris
accumulated over time does not.
For installations using two sensors, the duct smoke detector
does not differentiate which sensor signals an alarm or trouble
condition.
Fig. 18 — Smoke Detector Sensor
Smoke Detector Locations
SUPPLY AIR
The supply-air smoke detector sensor is located to the left of the
unit’s indoor (supply) fan (see Fig. 19). Access is through the fan
access panel. There is no sampling tube used at this location. The
sampling tube inlet extends through the side plate of the fan hous-
ing (into a high pressure area). The controller is located on a
bracket to the right of the return filter, accessed through the lift-off
filter panel.
Duct smoke sensor
controller
Fastener
(2X)
Controller cover
Conduit nuts
(supplied by installer)
Conduit support plate
Cover gasket
(ordering option)
Conduit couplings
(supplied by installer)
Terminal block cover
Controller housing
and electronics
Alarm Power
Test/reset
switch
Trouble
Duct smoke sensor
See
Detail A
Exhaust tube
Plug
Sampling tube
(ordered separately)
Intake
gasket Cover gasket
(ordering option)
TSD-CO2
(ordering option)
Sensor housing
and electronics
Exhaust gasket
Coupling
Sensor cover
Detail A
Magnetic
test/reset
switch
Alarm
Trouble
Power
Dirty

15
Fig. 19 — Typical Supply Air Smoke Detector Sensor
Location
RETURN AIR WITHOUT ECONOMIZER
The sampling tube is located across the return air opening on the
unit basepan. (See Fig. 20.) The holes in the sampling tube face
downward, into the return air stream. The sampling tube is con-
nected via tubing to the return air sensor that is mounted on a
bracket high on the partition between return filter and controller
location. (This sensor is shipped in a flat-mounting location. In-
stallation requires that this sensor be relocated to its operating lo-
cation and the tubing to the sampling tube be connected. See in-
stallation steps).
Fig. 20 — Typical Return Air Detector Location
RETURN AIR WITH ECONOMIZER
The sampling tube is inserted through the side plates of the econo-
mizer housing, placing it across the return air opening on the unit
basepan. (See Fig. 21.) The holes in the sampling tube face down-
ward, into the return air stream. The sampling tube is connected
via tubing to the return air sensor that is mounted on a bracket high
on the partition between return filter and controller location. (This
sensor is shipped in a flat-mounting location. Installation requires
that this sensor be relocated to its operating location and the tubing
to the sampling tube be connected. See installation steps).
Fig. 21 — Return Air Sampling Tube Location
Completing Installation of Return Air Smoke
Sensor
1. Unscrew the two screws holding the return air sensor detector
plate. (See Fig. 22.) Save the screws.
2. Remove the return air sensor and its detector plate.
3. Rotate the detector plate so the sensor is facing outwards and
the sampling tube connection is on the bottom. (See Fig. 23.)
4. Screw the sensor and detector plate into its operating position
using screws from Step 1. Make sure the sampling tube con-
nection is on the bottom and the exhaust tube is on the top.
(See Fig. 23.)
5. Connect the flexible tube on the sampling inlet to the sam-
pling tube on the basepan.
6. For units with an economizer, the sampling tube is integrated
into the economizer housing but the connection of the flexible
tubing to the sampling tube is the same.
Fig. 22 — Return Air Detector Shipping Position
SMOKE DETECTOR
SENSOR
*RA detector must be moved from shipping
position to operating position by installer.
RETURN AIR DETECTOR
SAMPLING TUBE
RETURN AIR
DETECTOR MODULE
(Shipping position
shown)*
CONTROLLER
MODULE
RETURN AIR
SAMPLING TUBE
SCREWS
FLEXIBLE
EXHAUST
TUBES
SAMPLE
TUBE

16
Fig. 23 — Return Air Sensor Operating Position
FIOP Smoke Detector Wiring and Response
ALL UNITS
FIOP smoke detector is configured to automatically shut down all
unit operations when smoke condition is detected. See Fig. 24.
HIGHLIGHT A
JMP 3 is factory-cut, transferring unit control to smoke detector.
HIGHLIGHT B
Smoke detector NC contact set will open on smoke alarm condi-
tion, de-energizing the ORN conductor.
HIGHLIGHT C
24-v power signal via ORN lead is removed at Smoke Detector in-
put on LCTB; all unit operations cease immediately.
HIGHLIGHT D
On smoke alarm condition, the smoke detector NO Alarm contact
will close, supplying 24-v power to GRA conductor.
HIGHLIGHT E
WHT lead at Smoke Alarm input on LCTB provides 24-v signal
to FIOP DDC control.
USING REMOTE LOGIC
Five conductors are provided for field use (see Highlight F in
Fig. 24) for additional annunciation functions.
ADDITIONAL APPLICATION DATA
Refer to the application data document “Factory Installed Smoke
Detectors for Small and Medium Rooftop Units 2 to 25 Tons” for
discussions on additional control features of these smoke detectors
including multiple unit coordination. (See Fig. 24.)
Fig. 24 — Typical Smoke Detector System Wiring
B
D
ACEF

17
Sensor and Controller Tests
SENSOR ALARM TEST
The sensor alarm test checks a sensor’s ability to signal an alarm
state. This test requires the use of a field provided SD-MAG test
magnet.
Sensor Alarm Test Procedure
1. Hold the test magnet where indicated on the side of the sensor
housing for seven seconds.
2. Verify that the sensor’s Alarm LED turns on.
3. Reset the sensor by holding the test magnet against the sensor
housing for two seconds.
4. Verify that the sensor’s Alarm LED turns off.
CONTROLLER ALARM TEST
The controller alarm test checks the controller’s ability to initiate
and indicate an alarm state.
Controller Alarm Test Procedure
1. Press the controller’s test/reset switch for seven seconds.
2. Verify that the controller’s Alarm LED turns on.
3. Reset the sensor by pressing the test/reset switch for two
seconds.
4. Verify that the controller’s Alarm LED turns off.
DIRTY CONTROLLER TEST
The dirty controller test checks the controller’s ability to initiate a
dirty sensor test and indicate its results.
Dirty Controller Test Procedure
1. Press the controller’s test/reset switch for two seconds.
2. Verify that the controller’s Trouble LED flashes.
DIRTY SENSOR TEST
The dirty sensor test provides an indication of the sensor’s ability
to compensate for gradual environmental changes. A sensor that
can no longer compensate for environmental changes is consid-
ered 100% dirty and requires cleaning or replacing. Use a field
provided SD-MAG test magnet to initiate a sensor dirty test. The
sensor’s Dirty LED indicates the results of the dirty test as shown
in Table 2.
Dirty Sensor Test Procedure
1. Hold the test magnet where indicated on the side of the sensor
housing for two seconds.
2. Verify that the sensor’s Dirty LED flashes.
Changing the Dirty Sensor Test
By default, sensor dirty test results are indicated by:
• The sensor’s Dirty LED flashing.
• The controller’s Trouble LED flashing.
• The controller’s supervision relay contacts toggle.
The operation of a sensor’s dirty test can be changed so that the
controller’s supervision relay is not used to indicate test results.
When two detectors are connected to a controller, sensor dirty test
operation on both sensors must be configured to operate in the
same manner.
To Configure the Dirty Sensor Test Operation
1. Hold the test magnet where indicated on the side of the sensor
housing until the sensor’s Alarm LED turns on and its Dirty
LED flashes twice (approximately 60 seconds).
2. Reset the sensor by removing the test magnet then holding it
against the sensor housing again until the sensor’s Alarm
LED turns off (approximately 2 seconds).
REMOTE STATION TEST
The remote station alarm test checks a test/reset station’s ability to
initiate and indicate an alarm state.
SD-TRK4 Remote Alarm Test Procedure
1. Turn the key switch to the RESET/TEST position for seven
seconds.
2. Verify that the test/reset station’s Alarm LED turns on.
IMPORTANT: Failure to follow this caution may result in
personnel and authority concern.
This test places the duct detector into the alarm state.
Unless part of the test, disconnect all auxiliary equipment
from the controller before performing the test. If the duct
detector is connected to a fire alarm system, notify the
proper authorities before performing the test.
IMPORTANT: Failure to follow this caution may result in
personnel and authority concern.
This test places the duct detector into the alarm state. Dis-
connect all auxiliary equipment from the controller before
performing the test. If the duct detector is connected to a
fire alarm system, notify the proper authorities before per-
forming the test.
IMPORTANT: Failure to follow this caution may result in
personnel and authority concern.
Pressing the controller’s test/reset switch for longer than
seven seconds will put the duct detector into the alarm state
and activate all automatic alarm responses.
IMPORTANT: Failure to follow this caution may result in
personnel and authority concern.
Holding the test magnet against the sensor housing for
more than seven seconds will put the duct detector into the
alarm state and activate all automatic alarm responses.
Table 2 — Dirty LED Test
FLASHES DESCRIPTION
10-25% dirty
(Typical of a newly installed detector)
225-50% dirty
351-75% dirty
476-99% dirty
IMPORTANT: Failure to follow this caution may result in
personnel and authority concern.
Changing the dirty sensor test operation will put the detec-
tor into the alarm state and activate all automatic alarm
responses. Before changing dirty sensor test operation, dis-
connect all auxiliary equipment from the controller and
notify the proper authorities if connected to a fire alarm
system.
IMPORTANT: Failure to follow this caution may result in
personnel and authority concern.
This test places the duct detector into the alarm state.
Unless part of the test, disconnect all auxiliary equipment
from the controller before performing the test. If the duct
detector is connected to a fire alarm system, notify the
proper authorities before performing the test.

18
3. Reset the sensor by turning the key switch to the RESET/
TEST position for two seconds.
4. Verify that the test/reset station’s Alarm LED turns off.
REMOTE TEST/RESET STATION DIRTY SENSOR TEST
The test/reset station dirty sensor test checks the test/reset station’s
ability to initiate a sensor dirty test and indicate the results. It must
be wired to the controller as shown in Fig. 25 and configured to
operate the controller’s supervision relay. For more information,
see “Changing the Dirty Sensor Test.”
Fig. 25 — Remote Test/Reset Station Connections
Dirty Sensor Test Using an SD-TRK4
1. Turn the key switch to the RESET/TEST position for two
seconds.
2. Verify that the test/reset station’s Trouble LED flashes.
DETECTOR CLEANING
Cleaning the Smoke Detector
Clean the duct smoke sensor when the Dirty LED is flashing con-
tinuously or sooner, if conditions warrant.
1. Disconnect power from the duct detector then remove the
sensor’s cover. (See Fig. 26.)
2. Using a vacuum cleaner, clean compressed air, or a soft bris-
tle brush, remove loose dirt and debris from inside the sensor
housing and cover. Use isopropyl alcohol and a lint-free cloth
to remove dirt and other contaminants from the gasket on the
sensor’s cover.
3. Squeeze the retainer clips on both sides of the optic housing
then lift the housing away from the printed circuit board.
4. Gently remove dirt and debris from around the optic plate and
inside the optic housing.
5. Replace the optic housing and sensor cover.
6. Connect power to the duct detector then perform a sensor
alarm test.
Fig. 26 — Sensor Cleaning Diagram
Indicators
NORMAL STATE
The smoke detector operates in the normal state in the absence of
any trouble conditions and when its sensing chamber is free of
smoke. In the normal state, the Power LED on both the sensor and
the controller are on and all other LEDs are off.
ALARM STATE
The smoke detector enters the alarm state when the amount of
smoke particulate in the sensor’s sensing chamber exceeds the
alarm threshold value. (See Table 3.)
Upon entering the alarm state:
• The sensor’s Alarm LED and the controller’s Alarm LED
turn on.
• The contacts on the controller’s two auxiliary relays switch
positions.
• The contacts on the controller’s alarm initiation relay
close.
• The controller’s remote alarm LED output is activated
(turned on).
• The controller’s high impedance multiple fan shutdown
control line is pulled to ground Trouble state.
IMPORTANT: Failure to follow this caution may result in
personnel and authority concern.
If the test/reset station’s key switch is left in the RESET/
TEST position for longer than seven seconds, the detector
will automatically go into the alarm state and activate all
automatic alarm responses.
IMPORTANT: Failure to follow this caution may result in
personnel and authority concern.
Holding the test magnet to the target area for longer than
seven seconds will put the detector into the alarm state and
activate all automatic alarm responses.
1
12
14
13
19
15
2
20
3
RESET/TEST
Trouble
POWER
ALARM
SUPERVISION RELAY
CONTACTS [3]
5
4
1
3
2
SD-TRK4
2
1
TB3
18 VDC (-)
18 VDC (-)
AUXILIARY
EQUIPMENT
+
−
WIRE MUST BE
ADDED BY
INSTALLER
SMOKE DETECTOR
CONTROLLER
IMPORTANT: Failure to follow this caution may result in
personnel and authority concern.
If the smoke detector is connected to a fire alarm system,
first notify the proper authorities that the detector is under-
going maintenance then disable the relevant circuit to avoid
generating a false alarm.
HVAC DUCT
SAMPLING
TUBE
RETAINER
CLIP
OPTIC
PLATE
OPTIC
HOUSING
SENSOR
HOUSING
AIRFLOW

19
The SuperDuct duct smoke detector enters the trouble state under
the following conditions:
• A sensor’s cover is removed and 20 minutes pass before it
is properly secured.
• A sensor’s environmental compensation limit is reached
(100% dirty).
• A wiring fault between a sensor and the controller is detected.
An internal sensor fault is detected upon entering the trouble state:
• The contacts on the controller’s supervisory relay switch
positions. (See Fig. 27.)
• If there is a sensor fault, the sensor’s trouble LED and the
controller trouble LED will turn on.
• If 100% dirty, the sensor’s Dirty LED turns on and the
controller’s Trouble LED flashes continuously.
• If a wiring fault between a sensor and the controller, the
controller’s Trouble LED turns on but not the sensor’s.
NOTE: All troubles are latched by the duct smoke detector. The
trouble condition must be cleared and then the duct smoke detec-
tor must be reset in order to restore it to the normal state.
Fig. 27 — Controller Assembly
Resetting Alarm and Trouble Condition Trips
Manual reset is required to restore smoke detector systems to Nor-
mal operation. For installations using two sensors, the duct smoke
detector does not differentiate which sensor signals an alarm or
trouble condition. Check each sensor for Alarm or Trouble status
(indicated by LED). Clear the condition that has generated the trip
at this sensor. Then reset the sensor by pressing and holding the re-
set button (on the side) for 2 seconds. Verify that the sensor’s
Alarm and Trouble LEDs are now off. At the controller, clear its
Alarm or Trouble state by pressing and holding the manual reset
button (on the front cover) for 2 seconds. Verify that the control-
ler’s Alarm and Trouble LEDs are now off. Replace all panels.
Troubleshooting
CONTROLLER’S TROUBLE LED IS ON
1. Check the Trouble LED on each sensor connected to the con-
troller. If a sensor’s Trouble LED is on, determine the cause
and make the necessary repairs.
2. Check the wiring between the sensor and the controller. If
wiring is loose or missing, repair or replace as required.
CONTROLLER’S TROUBLE LED IS FLASHING
1. One or both of the sensors is 100% dirty.
2. Determine which Dirty LED is flashing then clean that sensor
assembly as described in the detector cleaning section.
SENSOR’S TROUBLE LED IS ON
1. Check the sensor’s Dirty LED. If it is flashing, the sensor is
dirty and must be cleaned.
2. Check the sensor’s cover. If it is loose or missing, secure the
cover to the sensor housing.
3. Replace sensor assembly.
SENSOR’S POWER LED IS OFF
1. Check the controller’s Power LED. If it is off, determine why
the controller does not have power and make the necessary
repairs.
2. Check the wiring between the sensor and the controller. If
wiring is loose or missing, repair or replace as required.
CONTROLLER’S POWER LED IS OFF
1. Make sure the circuit supplying power to the controller is
operational. If not, make sure JP2 and JP3 are set correctly on
the controller before applying power.
2. Verify that power is applied to the controller’s supply input
terminals. If power is not present, replace or repair wiring as
required.
REMOTE TEST/RESET STATION’S TROUBLE LED DOES
NOT FLASH WHEN PERFORMING A DIRTY TEST, BUT
THE CONTROLLER’S TROUBLE LED DOES
1. Verify that the remote test/station is wired as shown in
Fig. 25. Repair or replace loose or missing wiring.
2. Configure the sensor dirty test to activate the controller’s
supervision relay. See “Changing sensor dirty test operation.”
SENSOR’S TROUBLE LED IS ON, BUT THE CONTROL-
LER’S TROUBLE LED IS OFF
Remove JP1 on the controller.
PROTECTIVE DEVICES
Compressor Protection
OVERCURRENT
Each compressor has internal linebreak motor protection. Reset is
automatic after compressor motor has cooled.
OVERTEMPERATURE
Each compressor has an internal protector to protect it against ex-
cessively high discharge gas temperatures. Reset is automatic.
HIGH PRESSURE SWITCH
Each system is provided with a high pressure switch mounted on
the discharge line. The switch is stem-mounted and brazed into the
discharge tube. Trip setting is 630 psig ± 10 psig (4344 ± 69 kPa)
when hot. Reset is automatic at 505 psig (3482 kPa).
Table 3 — Detector Indicators
CONTROL OR INDICATOR DESCRIPTION
Magnetic test/reset switch Resets the sensor when it is in the alarm or trouble state. Activates or tests the sensor when it is in the
normal state.
Alarm LED Indicates the sensor is in the alarm state.
Trouble LED Indicates the sensor is in the trouble state.
Dirty LED Indicates the amount of environmental compensation used by the sensor
(flashing continuously = 100%)
Power LED Indicates the sensor is energized.
ALARM POWER
TEST /RE SET
SWITCH
TROUBLE
RESET
ALARM
TROUBLE
POWER

20
LOW PRESSURE SWITCH
Each system is protected against a loss of charge and low evapora-
tor coil loading condition by a low pressure switch located on the
suction line near the compressor. The switch is stem-mounted.
Trip setting is 54 psig ± 5 psig (372 ± 34 kPa). Reset is automatic
at 117 ± 5 psig (807 ± 34 kPa).
Supply (Indoor) Fan Motor Protection
Disconnect and lockout power when servicing fan motor. The sup-
ply fan motor is equipped with an overcurrent protection device.
The type of device depends on the motor size. (See Table 4.)
The Internal Linebreak type is an imbedded switch that senses
both motor current and internal motor temperature. When this
switch reaches its trip setpoint, the switch opens the power supply
to the motor and the motor stops. Reset is automatic when the mo-
tor windings cool down.
The Thermik device is a snap-action overtemperature protection
device that is imbedded in the motor windings. It is a pilot-circuit
device that is wired into the unit’s 24-v control circuit. When this
switch reaches its trip setpoint, it opens the 24-v control circuit and
causes all unit operation to cease. This device resets automatically
when the motor windings cool. Do not bypass this switch to cor-
rect trouble. Determine the cause and correct it.
The External motor overload device is a specially-calibrated cir-
cuit breaker that is UL recognized as a motor overload controller.
It is an overcurrent device. When the motor current exceeds the
circuit breaker setpoint, the device opens all motor power leads
and the motor shuts down. Reset requires a manual reset at the
overload switch. This device (designated IFCB) is located on the
side of the supply fan housing, behind the fan access panel.
TROUBLESHOOTING SUPPLY FAN MOTOR OVER-
LOAD TRIPS
The supply fan used in 50LC units is a forward-curved centrifugal
wheel. At a constant wheel speed, this wheel has a characteristic
that causes the fan shaft load to DECREASE when the static pres-
sure in the unit-duct system increases and to INCREASE when
the static pressure in the unit-duct system decreases (and fan air-
flow rate increases). Motor overload conditions typically develop
when the unit is operated with an access panel removed, with un-
finished duct work, in an economizer-open mode, or a leak devel-
ops in the duct system that allows a bypass back to unit return
opening.
Condenser Fan Motor Protection
The condenser fan motors are internally protected against
overtemperature.
Control Circuit, 24-v
The control circuit is protected against overcurrent conditions by a
circuit breaker mounted on control transformer TRAN. Reset is
manual.
ELECTRIC HEATERS
The 50LC units may be equipped with field-installed accessory
electric heaters. The heaters are modular in design, with heater
frames holding open coil resistance wires strung through ceramic
insulators, line-break limit switches and a control contactor. One
or two heater modules may be used in a unit.
Heater modules are installed in the compartment below the indoor
(supply) fan outlet. Access is through the indoor access panel.
Heater modules slide into the compartment on tracks along the
bottom of the heater opening. (See Fig. 28-30.)
Not all available heater modules may be used in every unit. Use
only those heater modules that are UL listed for use in a specific
size unit. Refer to the label on the unit cabinet for the list of ap-
proved heaters.
Unit heaters are marked with heater model numbers. But heaters
are ordered as and shipped in cartons marked with a correspond-
ing heater sales package part number.
NOTE: The value in position 9 of the part number differs between
the sales package part number (value is 1) and a bare heater model
number (value is 0).
Fig. 28 — Typical Access Panel Location
Fig. 29 — Typical Component Location
Table 4 — Supply Fan Motor Protection Devices
MOTOR SIZE (BHP) OVERLOAD DEVICE RESET
1.7 Internal linebreak Automatic
2.4 Internal linebreak Automatic
2.9 Thermik Automatic
3.7 Thermik Automatic
5.2 External (circuit breaker) Manual
DISCONNECT MOUNTING
LOCATION
UNIT BLOCK-OFF
PANEL
OUTDOOR
ACCESS PANEL
INDOOR
ACCESS
PANEL
DISCONNECT
MOUNTING
LOCATION
EMT OR RIGID CONDUIT
(FIELD-SUPPLIED)
SINGLE
POINT BOX
CENTER
POST
HEATER
COVERS
HEATER
MOUNTING
BRACKET
HEATER
MODULE
(LOCATION 2)
HEATER
MODULE
(LOCATION 1)
SINGLE POINT
BOX
MOUNTING
SCREW
BRACKET AND
CONDUIT
DRIP BOOT
MAIN
CONTROL
BOX
CONTROL WIRE TERMINAL BLOCK
MANUAL RESET
LIMIT SWITCH