Carrier WeatherMaker 50TCQ 17-24 Series 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. 04-53500229-01 Printed in U.S.A. Form 50TCQ-17-24-02SM Pg 1 8-2020 Replaces: 50TCQ-17-24-01SM
Service and Maintenance Instructions
CONTENTS
Page
SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . 2
UNIT ARRANGEMENT AND ACCESS . . . . . . . . . . . . 2
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Routine Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . 2
Seasonal Maintenance . . . . . . . . . . . . . . . . . . . . . . . . 3
SUPPLY FAN (BLOWER) SECTION . . . . . . . . . . . . . . 3
Supply Fan (Belt-Drive) . . . . . . . . . . . . . . . . . . . . . . . 3
Belt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Adjustable-Pitch Pulley on Motor . . . . . . . . . . . . . . . 4
Changing the Fan Speed . . . . . . . . . . . . . . . . . . . . . . 5
Aligning Fan and Motor Pulleys . . . . . . . . . . . . . . . . 5
Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
STAGED AIR VOLUME (SAV) CONTROL: 2-SPEED
FAN WITH VARIABLE FREQUENCY
DRIVE (VFD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Staged Air Volume (SAV) Indoor Fan Speed
System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Identifying Factory Option . . . . . . . . . . . . . . . . . . . . . 5
Unit Installation with SAV Option . . . . . . . . . . . . . . . 6
ADDITIONAL VFD INSTALLATION AND
TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . 6
HEAT PUMP REFRIGERATION SYSTEM . . . . . . . . . 6
Outdoor Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Indoor Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Recommended Coil Maintenance and Cleaning . . . 6
Refrigeration System Components . . . . . . . . . . . . . . 8
Reversing Valve and Check Valve Position . . . . . . . 9
Troubleshooting Refrigerant Pressure Problems and
Check Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Refrigerant System Pressure Access Ports . . . . . . 10
THERMOSTATIC EXPANSION VALVE (TXV) . . . . . 11
TXV Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Replacing TXV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
PURON (R-410A) REFRIGERANT . . . . . . . . . . . . . . 12
Refrigerant Charge . . . . . . . . . . . . . . . . . . . . . . . . . . 12
How To Use Cooling Charging Charts . . . . . . . . . . 12
COOLING CHARGING CHARTS . . . . . . . . . . . . . . . . 13
Compressors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Troubleshooting Cooling System . . . . . . . . . . . . . . 17
CONVENIENCE OUTLETS . . . . . . . . . . . . . . . . . . . . 19
Installing Weatherproof Cover . . . . . . . . . . . . . . . . . 19
Duty Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Fuse on Power Type . . . . . . . . . . . . . . . . . . . . . . . . . 20
Using Unit-mounted Convenience Outlets . . . . . . . 20
HEAT PUMP CONTROLS . . . . . . . . . . . . . . . . . . . . . 20
Central Terminal Board . . . . . . . . . . . . . . . . . . . . . . 20
PROTECTIVE CONTROLS . . . . . . . . . . . . . . . . . . . . .21
Compressor Protection . . . . . . . . . . . . . . . . . . . . . . .21
Supply (Indoor) Fan Motor Protection . . . . . . . . . . .21
Outdoor Fan Motor Protection . . . . . . . . . . . . . . . . .21
Control Circuit, 24v . . . . . . . . . . . . . . . . . . . . . . . . . .21
COMMERCIAL DEFROST CONTROL . . . . . . . . . . . .21
Reversing Valve Control . . . . . . . . . . . . . . . . . . . . . .22
Compressor Control . . . . . . . . . . . . . . . . . . . . . . . . .22
Auxiliary (Electric) Heat Control . . . . . . . . . . . . . . . .22
Defrost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Indoor Fan Off Delay . . . . . . . . . . . . . . . . . . . . . . . . .23
Defrost Speedup Functions . . . . . . . . . . . . . . . . . . .23
ELECTRIC HEATERS . . . . . . . . . . . . . . . . . . . . . . . . .23
Single Point Boxes and Supplementary Fuses . . . .25
Completing Heater Installation . . . . . . . . . . . . . . . . .26
SMOKE DETECTORS . . . . . . . . . . . . . . . . . . . . . . . . .26
System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Smoke Detector Locations . . . . . . . . . . . . . . . . . . . .27
Completing Installation of Return Air Smoke
Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
FIOP Smoke Detector Wiring and Response . . . . .30
Sensor and Controller Tests . . . . . . . . . . . . . . . . . . . 30
Detector Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . .32
INDICATORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Normal State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Alarm State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Resetting Alarm and Trouble Condition Trips . . . .33
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
PremierLink™ Control . . . . . . . . . . . . . . . . . . . . . . . .33
RTU Open Control System . . . . . . . . . . . . . . . . . . . .33
ECONOMI$ER SYSTEMS . . . . . . . . . . . . . . . . . . . . . .33
EconoMi$er IV Standard Sensors . . . . . . . . . . . . . .38
EconoMi$er® X (Factory Option) . . . . . . . . . . . . . . .43
PRE-START-UP / START-UP . . . . . . . . . . . . . . . . . . .57
START-UP, GENERAL . . . . . . . . . . . . . . . . . . . . . . . .57
Additional Installation/Inspection . . . . . . . . . . . . . .57
START-UP, PREMIERLINK CONTROLS . . . . . . . . . .58
START-UP, RTU-OPEN CONTROLS . . . . . . . . . . . . .58
FASTENER TORQUE VALUES . . . . . . . . . . . . . . . . .59
APPENDIX A —MODEL NUMBER
NOMENCLATURE . . . . . . . . . . . . . . . . . . . . . . . . . .60
APPENDIX B —PHYSICAL DATA . . . . . . . . . . . . . . .61
APPENDIX C —FAN PERFORMANCE . . . . . . . . . . .64
APPENDIX D —WIRING DIAGRAMS . . . . . . . . . . . .67
APPENDIX E —MOTORMASTER SENSOR
LOCATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73
START-UP CHECKLIST . . . . . . . . . . . . . . . . . . . . .CL-1
WeatherMaker®
50TCQ*17-24
Single Package Rooftop Unit with Heat Pump
with Puron®(R-410A) Refrigerant

2
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.
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.
UNIT ARRANGEMENT AND ACCESS
General
Figures 1 and 2 show general unit arrangement and access
locations.
Fig. 1 — Typical Access Panel Location (Front)
Fig. 2 — Typical Access Panel Locations (Rear)
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)
• Replace return air filter
• Clean outdoor hood inlet filters
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.
WARNING
FIRE, EXPLOSION HAZARD
Failure to follow this warning could result in death, serious
personal injury and/or property damage.
Never use air or gases containing oxygen for leak testing or for
operating refrigerant compressors. Pressurized mixtures of air
or gases containing oxygen can lead to an explosion.
WARNING
FIRE, EXPLOSION HAZARD
Failure to follow this warning could result in death, serious
personal injury and/or property damage.
Never use non-certified refrigerants in this product. Non-certi-
fied refrigerants could contain contaminates that could lead to
unsafe operating conditions. Use ONLY refrigerants that con-
form to AHRI Standard 700.
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.
ELECTRIC HEAT
ACCESS PANEL
CONTROL
BOX
ACCESS
PANEL
FILTER
AND
INDOOR
COIL
ACCESS
PANEL
INDOOR
BLOWER
ACCESS
PANEL
FILTER
ACCESS
PANEL

3
• Check belt tension
• Check belt condition
• Inspect pulley alignment
• Check fan shaft bearing locking collar tightness
• Check outdoor coil cleanliness
• Check condensate drain
Seasonal Maintenance
The following items should be checked at the beginning of
each season (or more often if local conditions and usage pat-
terns dictate).
AIR CONDITIONING/HEAT PUMP
• Ensure outdoor fan motor mounting bolts are tight
• Ensure compressor mounting bolts are tight
• Inspect outdoor fan blade positioning
• Ensure control box is clean of dirt and debris
• Check control box wiring condition
• Ensure wire terminals are tight
• Check refrigerant charge level
• Ensure indoor coils are clean
• Check supply blower motor amperage
ELECTRIC HEATING
• Inspect power wire connections
• Ensure fuses are operational
• Ensure manual-reset limit switch is closed
ECONOMIZER OR OUTSIDE AIR DAMPER
• Check inlet filters condition
• Check damper travel (economizer)
• Check gear and dampers for dirt and debris
AIR FILTERS AND SCREENS
Each unit is equipped with return air filters. If the unit has an econ-
omizer, it also has an outside air screen. If a manual outside air
damper is added, it also has an inlet air screen.
Each of these filters and screens will need periodic cleaning or
replacement.
RETURN AIR FILTERS
Return air filters are disposable fiberglass filters. Access to the fil-
ters is through the filter and indoor coil access panel located to the
right of the control box. The filters are situated on slide out racks
for easy inspection and replacement. See Fig. 1.
Removing the return air filters:
1. Remove the vertical filter access panel.
2. Reach into the filter access opening and remove the filters
from the filter rack.
3. Replace filters as required with similar replacement filters of
same size.
Installing the return filters and access panel:
1. Slide the filters into the slide-out racks.
2. Place the vertical filter access panel on the unit.
3. Replace the mounting hardware attaching the panel to the
unit and tighten securely.
OUTSIDE AIR HOOD
Outside air hood inlet screens are permanent aluminum-mesh type
filters. Check filters for dirt and debris. 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 when reinstalling.
ECONOMIZER AND MANUAL OUTSIDE AIR SCREENS
This air screen is retained by spring clips under the top edge of the
hood. (See Fig. 3.)
To remove the filter, remove screws in horizontal filter retainers
on leading edge of hood. Slide filters out. To re-install filters, slide
clean or new filters into hood side retainers. Once positioned, re-
install horizontal filter retainer.
Fig. 3 — Filter Installation
SUPPLY FAN (BLOWER) SECTION
Supply Fan (Belt-Drive)
The belt-drive 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
driver pulley is attached to the fan shaft and an adjustable-pitch
driver pulley is on the motor. The pulleys are connected using a V-
belt. See Fig. 4.
CAUTION
EQUIPMENT DAMAGE HAZARD
Failure to follow this CAUTION can result in premature wear
and damage to equipment.
DO NOT OPERATE THE UNIT WITHOUT THE RETURN
AIR FILTERS IN PLACE.
Dirt and debris can collect on heat exchangers and coils possi-
bly resulting in a small fire. Dirt buildup on components can
cause excessive current used resulting in motor failure.
IMPORTANT: DO NOT OPERATE THE UNIT WITHOUT
RETURN-AIR FILTERS!
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.

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 surfaces.
Check belt tension by using a spring-force tool (such as Brown-
ing’s “Belt Tension Checker” (P/N 1302546 or equivalent tool);
tension should be 6 lb at a 5/8-in. (1.6 cm) deflection when mea-
sured 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 straightedge
across the belt surface at the pulleys, then push down on the belt at
mid-span using one finger until a 1/2-in. (1.3 cm) deflection is
reached. See Fig. 5.
Adjust belt tension by loosening the motor mounting plate
front and rear bolts and sliding the plate toward the fan (to re-
duce tension) or away from fan (to increase tension). Ensure
the blower shaft and the motor shaft are parallel to each other
(pulleys aligned). When finished, tighten all bolts and torque to
65 to 70 in.-lb (7.4 to 7.9 Nm).
Fig. 5 — Checking Blower Motor Belt Tension
REPLACING THE V-BELT
NOTE: Use a belt with the same section type or similar size. Do
not substitute a FHP-type (cogged) belt. When installing the new
belt, do not use a screwdriver or pry-bar to force the belt over the
pulley flanges, this will stress the belt and cause a reduction in belt
life. Damage to the pulley can also occur.
1. Loosen the four front and rear motor mounting plate bolts
(see Fig. 6).
2. Loosen the two jack bolt jam nuts.
3. Turn the two jack bolts counterclockwise to loosen bringing
the motor closer to the blower.
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. Turn the jack bolts clockwise to increase the tension of the V-
belt.
7. Adjust the V-belt tension using Browning’s “Belt Tension
Checker” (P/N 1302546 or equivalent tool) to 6 lb at a 5/8-in.
(1.6 cm) deflection when measured at the centerline of the
belt span. The tension can also be checked depressing the belt
at mid-span with one finger until a ½-in (1.3 cm) deflection is
reached.
8. Check alignment of the pulleys, adjust the motor mounting
base as needed. Tighten four motor mounting bolts. Torque
all bolts to 65 to 70 in.-lb (7.4 to 7.9 Nm).
9. Tighten two jack bolt jam nuts. Torque jam nuts to 65 to
70 in.-lb (7.4 to 7.9 Nm).
10. Check the tension after a few hours of runtime and re-adjust
as required.
Fig. 6 — Replacing the V-Belt
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 previously
installed ductwork systems. The pulley consists of a fixed flange
side that faces the motor (secured to the motor shaft) and a mov-
able flange side that can be rotated around the fixed flange side
that increases or reduces the pitch diameter of this driver pulley.
See Fig. 7.
BROWNING BELT
TENSION CHECKER
STRAIGHTEDGE
1/2”
(1.3 cm)
BELT
DEFLECTION
CAUTION
EQUIPMENT DAMAGE HAZARD
Failure to follow this CAUTION can result in premature wear
and damage to equipment.
Do not use a screwdriver or a pry bar to place the new V-belt in
the pulley groove. This can cause stress on the V-belt and the
pulley resulting in premature wear on the V-belt and damage
to the pulley.
BLOWER PULLEY
V-BELT
MOTOR PULLEY
MOTOR
MOTOR MOUNTING
BRACKET BOLTS (4)
MOTOR MOUNTING
BRACKET (2)
JACK BOLT JAM NUT (2)
JACK BOLT (2)

5
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. 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. Replace pulley if
necessary.
Fig. 7 — Supply-Fan Pulley Adjustment
Changing the Fan Speed
1. Shut off unit power supply. Use proper lockout/tag-out
procedures.
2. Loosen belt by loosening fan motor mounting nuts. See
Fig. 7.
3. Loosen movable pulley flange setscrew. See Fig. 7.
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 the maximum
specified speed.
5. Set movable flange at nearest keyway of pulley hub. Tighten
setscrew and torque to 65 to 70 in.-lb (7.4 to 7.9 Nm).
Aligning Fan and Motor Pulleys
1. Loosen fan pulley setscrews.
2. Slide fan pulley along fan shaft. Make angular alignment by
loosening motor mounting plate front and rear bolts.
3. Tighten fan pulley setscrews and motor mounting bolts and
torque to 65 to 70 in.-lb (7.4 to 7.9 Nm).
4. Recheck belt tension.
Bearings
The fan system uses bearings featuring concentric split locking
collars. A Torx1 T25 socket head cap screw is used to tighten the
locking collars. Tighten the locking collar by holding it firmly
against the inner race of the bearing and tightening the socket head
cap screw. Torque the socket head cap screw 55 to 60 in.-lb (6.2 to
6.8 Nm). See Fig. 8.
Fig. 8 — Tightening Locking Collar
Motor
Always replace the external-tooth lock washer (star washer) under
the motor mounting base; this is part of the motor grounding sys-
tem. Ensure the teeth on the lock washer are in contact with the
motor’s painted base. Tighten motor mounting bolts and torque to
120 ± 12 in.- lb (14 ± 1.4 Nm).
Change fan wheel speed by changing the 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). 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 mo-
tor pulley with a smaller pitch diameter than was provided on the
original factory pulley.
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 or use
the Packaged Rooftop Builder software program. Confirm that the
motor in this unit is capable of operating at the new operating
condition. Fan shaft loading increases dramatically 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.
STAGED AIR VOLUME (SAV) CONTROL: 2-
SPEED FAN WITH VARIABLE FREQUENCY
DRIVE (VFD)
Staged Air Volume (SAV) Indoor Fan Speed
System
The SAV system utilizes a fan speed control board and Variable
Frequency Drive (VFD) to automatically adjust the indoor fan
motor speed in sequence with the unit’s ventilation, cooling and
heating operation. Conforming to ASHRAE 90.1 2010 Standard
Section 6.4.3.10.b, during the first stage of cooling operation the
SAV system will adjust the fan motor to provide 66% of the de-
sign airflow rate for the unit. When the call for the second stage of
cooling is required, the SAV system will allow the design airflow
rate for the unit established (100%). During the heating mode, the
SAV system will allow total design airflow rate (100%) operation.
During ventilation mode, the SAV system will operate the fan mo-
tor at 66% speed.
Identifying Factory Option
This section only applies to units that meet the criteria detailed in
Table 1. See Appendix A for the model number nomenclature
breakdown.
1. Torx is a registered trademark of Acument Intellectual Properties
LLC.
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

6
Unit Installation with SAV Option
50TCQ ROOFTOP
Refer to the base unit installation instructions for standard required
operating and service clearances.
NOTE: The Remote VFD Keypad is a field-installed option. It is
not included as part of the factory-installed VFD option. See
“Variable Frequency Drive (VFD) Installation, Setup and Trouble-
shooting Supplement” for wiring schematics and performance
charts and configuration. See Fig. 9 for location of the VFD as
mounted on the various 50TCQ models.
Fig. 9 — VFD Location for 50TCQ 15-20 Ton Units
ADDITIONAL VFD INSTALLATION AND
TROUBLESHOOTING
Additional installation, wiring and troubleshooting information
for the VFD can be found in the following manuals: “Variable Fre-
quency Drive (VFD) Installation, Setup and Troubleshooting Sup-
plement.”
HEAT PUMP REFRIGERATION SYSTEM
Outdoor Coil
The 50TCQ outdoor coil is fabricated with round tube copper
hairpins and plate fins of various materials and/or coatings (see
Appendix A to identify the materials provided in this unit). All
unit sizes use composite-type two-row coils. Composite two-row
coils are two single-row coils fabricated with a single return bend
end tubesheet.
Indoor Coil
The indoor 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.
Recommended Coil Maintenance and Cleaning
Routine cleaning of coil surfaces is essential in maintaining 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 can 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 the coating of a pro-
tected coil) when 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
and dirt must be completely removed prior to using low velocity
clean water 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 INDOOR COIL SURFACES
Periodic cleaning with Totaline® Environmentally Sound Coil
Cleaner is essential in extending the life of coils. This cleaner is
available from Carrier Replacement Components Division (P/N
P902-0301 for a one gallon (3.8L) container, and P/N P902-0305
for a 5 gallon (19L) container). It is recommended that all coils
(including standard aluminum, pre-coated, copper/copper or E-
coated coils) be cleaned with the Totaline Environmentally Sound
Coil Cleaner as described below.
Coil cleaning should be part of the unit’s regularly scheduled
maintenance procedures ensuring the long life of the coil. Failure
to clean the coils can result in reduced durability in the
environment.
Avoid the use of:
• coil brighteners
• acid cleaning prior to painting
• high pressure washers
Table 1 — Model-Size / VFD Option Indicator
UNIT POSITION
IN MODEL NUMBER
VFD FIOP
INDICATOR
50TCQ 17,24 17 G, J
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
refrigerant may be used in this system. Gage set, hoses, and
recovery system must be designed to handle R-410A
refrigerant. If unsure about equipment, consult the equipment
manufacturer.
VARIABLE
FREQUENCY
DRIVE (VFD)
CAUTION
UNIT DAMAGE HAZARD
Failure to follow this caution can result in reduced unit perfor-
mance or unit shutdown.
Use only the recommended approved cleaning procedures for
proper system performance.

7
• 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 the coil or surrounding components,
such as electrical wiring, painted metal surfaces or insulation. Use
of non-recommended coil cleaners is strongly discouraged be-
cause coil and unit durability can be affected.
Clean coil as follows
1. Turn off unit power. Use lockout/tag-out procedures on unit
power switch.
2. Remove top panel screws on outdoor section.
3. Remove coil corner posts and access panel. See Fig. 10.
4. Lift and hold top cover open.
5. Hold the top panel open by placing the coil corner post
between the top panel and the center post. See Fig. 11.
6. Remove fasteners holding coil sections together at return end
of condenser coil. Carefully separate the outdoor coil section
three to four inches. See Fig. 12.
7. Clean the outer surfaces with a stiff brush in the normal man-
ner. Use a water hose or other suitable equipment to flush
down between the two coil sections to remove dirt and debris.
8. Secure inner and outer coil rows together with a field-sup-
plied fastener.
9. Reposition the outer coil section and remove the coil corner
post from between the top panel and center post. Reinstall
both coil corner posts and access panel. Replace all screws.
See Fig. 10.
Fig. 10 — Cleaning Condenser Coil
Fig. 11 — Propping Up Top Panel
Fig. 12 — Separating Coil Sections
Totaline Environmentally Sound Coil Cleaner Application
Equipment:
• 2.5 gal (9.5L) garden sprayer
• Water rinse with low velocity spray nozzle
Totaline Environmentally Sound Coil Cleaner Application
Instructions:
1. Proper protection equipment, such as approved safety glasses
and gloves, is recommended during mixing and application
of Totaline environmentally sound coil cleaner.
2. Remove all surface loaded fibers and debris using a vacuum
cleaner or a soft non-metallic bristle brush as described
above.
3. Thoroughly wet all finned surfaces with clean water using a
low velocity garden hose being careful not to bend fins.
4. Mix Totaline environmentally sound coil cleaner in a 2.5 gal
(9.5L) garden sprayer according to the instructions included
SCREWS(TYPICAL)
CORNER
POST
CORNER
POST
ACCESS
PAN E L
TOP PANEL
SCREWS
(TYPICAL)
OUTDOOR
COIL
OUTDOOR
COIL
COMPRESSOR
ACCESS PAN E L
COMPRESSOR
ACCESS
PANEL
COIL CORNER POSTCENTER
BAFFLE
TOP PANEL
CONDENSER
COILS
CAUTION
UNIT DAMAGE HAZARD
Failure to follow this caution may result in accelerated corro-
sion 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 dissim-
ilar 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.

8
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 sound 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.
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.
Refrigeration System Components
Each heat pump refrigeration system includes a compressor, accu-
mulator, reversing valve, dual-function outdoor coil with vapor
header check valve, cooling liquid line with a filter drier and a
check valve, dual-function indoor coil with a vapor header check
valve, and heating liquid line with check a valve and a strainer.
Unit sizes D17 - D24 have two compressor circuits. See Fig. 13
for typical unit piping schematic.
Dual-function outdoor and indoor coils are designed to provide
parallel coil circuits during evaporator-function operation and con-
verging coil circuits during the condenser-function operation.
Refrigerant flow metering in the evaporator-function sequence is
provided by multiple Accutrol™ fixed-bore metering devices that
are located in the tee nipples between the liquid header and the en-
trance to each coil circuit. The Accutrol metering device is brazed
into the nipple tube between the liquid header end and the side-
port tube. See Fig. 14. During evaporator-function operation, flow
is straight through the nipple and into each evaporator circuit.
Flow continues through the parallel evaporator circuits and into
the vapor header.
Fig. 13 — Typical Unit Piping Schematic with TXV Valves on the Indoor Coils
COMPRESSOR
ACCUMULATOR
HPS
COMPRESSOR
ACCUMULATOR
HPS
Filter
Drier 2B
1B
LPS/LOC
Acutrol DFT 1
Cooling Liquid Lines
DFT 2
2A
1A
1D
2D
Outdoor Coil
Indoor Coil
Comp 2
Comp 1
2C
1C Strainer
Heating Mode Liquid Lines
Acutrol
Reversing
Valve
Reversing
Valve

9
Fig. 14 — Heat Pump — Flow as Evaporator Function
OUTDOOR COILS ONLY
Converging circuit flow in the condenser-function operation is ac-
complished with the check valve in the vapor header and the liq-
uid transfer header connected to the side ports on all but one of the
Accutrol tee nipples in each circuit. During condenser-function
operation, hot gas from the compressor discharge enters the head-
er until it reaches the check valve which blocks further flow. The
hot gas exits the header through the tubes above the check valve
and enters these coil circuits. At the outlet of these desuperheating
and condensing circuits, the refrigerant enters the Accutrol tees
from the coil end. The refrigerant exits the tee at the side port and
enters the liquid transfer header (see Fig. 15). The refrigerant
moves through the liquid transfer header and exits through the
remaining tubes, through the side ports on the Accutrol tees (see
Fig. 16) and back into the coil circuits where additional condens-
ing occurs. These circuits exit into the vapor header behind the
check valve and exit through the remaining tube on the vapor
header. In this last pass through the coil, the refrigerant is sub-
cooled. Subcooled liquid exits at the last Accutrol tee (see Fig. 17)
where the side port is connected to the specific mode liquid line.
Each liquid line has a check valve to prevent back-flow through
the liquid line in its opposite mode. This ensures correct flow di-
rection through the filter driers and the strainers preventing emp-
tying of off-mode liquid lines into the evaporator-function coil
circuits.
Fig. 15 — Heat Pump Accutrol — Flow as Condenser
Function/Exiting First Pass
Fig. 16 — Heat Pump Accutrol — Flow as Condenser
Function/Entering Second Pass
Fig. 17 — Heat Pump Accutrol— Flow as Condenser
Function/Exiting Subcooler Pass
Reversing Valve and Check Valve Position
See Fig. 13 and Tables 2-4.
TO
EVAPORATOR
COIL
CIRCUITS
FROM
LIQUID
HEADER
FROM
CONDENSER
COIL CIRCUITS
TO
TRANSFER
HEADER
Table 2 — Cooling Mode (each circuit)
COMPONENT STATUS/POSITION
Reversing Valve Energized
Check Valve A Closed
Check Valve B Open
Check Valve C Closed
Check Valve D Open
Table 3 — Heating Mode (each circuit)
COMPONENT STATUS/POSITION
Reversing Valve De-energized
Check Valve A Open
Check Valve B Closed
Check Valve C Open
Check Valve D Closed
Table 4 — Defrost Mode
COMPONENT STATUS/POSITION
Defrost Thermostat Closed
Outdoor Fan(s) Off
Reversing Valve Energized
Check Valve A Closed
Check Valve B Open
Check Valve C Closed
Check Valve D Open
TO
CONDENSING
CIRCUIT
FROM
TRANSFER
HEADER
FROM
SUBCOOLER
CIRCUIT
TO
LIQUID
LINE
DFT LOCATION
(OUTDOOR COILS ONLY)

10
Troubleshooting Refrigerant Pressure Problems
and Check Valves
Refer to Fig. 13, on page 8, and the Cooling Mode and Heating
Mode tables (Tables 2-4).
COIL METERING DEVICES (OUTDOOR COILS ONLY)
The metering devices are multiple fixed-bore devices (Accutrol)
brazed into the horizontal outlet tubes from the liquid header, lo-
cated at the entrance to each evaporator coil circuit path. These
metering devices are non-adjustable. Service requires replacing
the entire liquid header assembly.
Check for possible blockage of one or more of these metering de-
vices by creating a low load condition on the evaporator-function
coil and then observing the frosting pattern on the finned portion
of the coil.
To check the indoor coil, disconnect the supply fan signal or con-
tactor (IFC) coil, then start the circuit in a Cooling Mode (jumper
R to Y1 or Y2) and observe the frosting pattern on the face of the
indoor coil. A frost pattern should develop uniformly across the
face of the indoor coil starting at each tube at the Accutrol nipple
locations.
To check the outdoor coil, disconnect the outdoor fan motor. Start
the circuit in a Heating Mode (jumper R to W1 or W2) and ob-
serve the frost pattern on the face of the outdoor coil.
Failure to develop frost at an outlet tube can indicate a plugged or
a missing orifice.
Refrigerant System Pressure Access Ports
There are two access ports in each circuit - on the suction tube and
the discharge tube near the compressor. 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 receptacle
base brazed to the tubing and an integral spring-closed check
valve core screwed into the base. See Fig. 18. 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 and torque to 96 ± 10 in.-lb (10.9 ±
1 Nm). Do not over-tighten.
Fig. 18 — 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)

11
Fig. 19 — Thermostatic Expansion Valve (TXV) Operation
THERMOSTATIC EXPANSION VALVE (TXV)
All 50TCQ units have a factory installed nonadjustable thermo-
static expansion valve (TXV). The TXV will be a bi-flow, bleed
port expansion valve with an external equalizer. TXVs are specifi-
cally designed to operate with Puron® refrigerant; use only factory
authorized TXVs. See Fig. 19.
TXV Operation
The TXV is a metering device that is used in air conditioning and
heat pump systems to adjust to changing load conditions by main-
taining a preset superheat temperature at the outlet of the evapora-
tor coil. The volume of refrigerant metered through the valve seat
is dependent upon the following.
1. Superheat temperature is sensed by the cap tube sensing bulb
on the suction tube at outlet of the evaporator coil. This tem-
perature is converted into pressure by refrigerant in the bulb
pushing downward on the diaphragm which opens the valve
using the push rods. As long as this bulb and cap tube contain
any liquid refrigerant, this temperature is converted into suc-
tion pressure pushing downward on the diaphragm, which
tends to open the TXV valve through the push rods.
2. The suction pressure at the outlet of the evaporator coil is
transferred through the external equalizer tube to the under-
side of the diaphragm.
3. The needle valve on the pin carrier is spring loaded, exerting
pressure on the underside of the diaphragm. Therefore, the
bulb pressure equals evaporator pressure (at outlet of coil)
plus spring pressure. If the load increases, the temperature
increases at the bulb, which increases the pressure on the top
side of the diaphragm, pushing the carrier away from the seat,
opening the valve and increasing the flow of refrigerant. The
increased refrigerant flow causes increased leaving evapora-
tor pressure which is transferred through the equalizer tube to
the underside of the diaphragm. This causes pin carrier spring
pressure to close the TXV valve. The refrigerant flow is
effectively stabilized to the load demand with a negligible
change in superheat.
Replacing TXV
1. Recover refrigerant.
2. Remove TXV support clamp using a 5/l6-in. nut driver.
3. Remove TXV using a backup wrench on connections to pre-
vent damage to tubing.
4. Remove equalizer tube from suction line of coil. Use file or
tubing cutter to cut brazed equalizer line approximately
2 inches above suction tube.
5. Remove bulb from vapor tube inside cabinet.
6. Install the new TXV and avoid damaging the tubing or the
valve when attaching the TXV to the distributor.
7. Attach equalizer tube to suction line. If coil has mechanical
connection, then use wrench and back up wrench to attach. If
coil has brazed connection, use file or tubing cutters to
remove mechanical flare nut from equalizer line. Then use
coupling to braze the equalizer line to stub (previous equal-
izer line) in suction line.
8. Attach TXV bulb in the same location as original (in the sens-
ing bulb indent), wrap bulb in protective insulation and
secure using the supplied bulb clamp. See Fig. 20.
9. Route equalizer tube through suction connection opening
(large hole) in fitting panel and install fitting panel in place.
10. Sweat inlet of TXV marked “IN” to liquid line. Avoid exces-
sive heat which could damage valve.
OUTLET
INLET
PUSHRODS
DIAPHRAGM
NEEDLE
VALVE
SPRING
DISTRIBUTOR
FEEDER TUBES
CAPILLARY TUBE
COIL
BULB
EXTERNAL EQUALIZER TUBE
CAUTION
PERSONAL INJURY HAZARD
Failure to follow this caution can result in injury to personnel
and damage to components.
Always wear approved safety glasses, work gloves and other
recommended Personal Protective Equipment (PPE) when
working with refrigerants.

12
Fig. 20 — TXV Valve and Sensing Bulb
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. Add liquid refrigerant into the system in the discharge
line. If adding refrigerant into the suction line, use a commercial
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 remove
Puron (R-410A) refrigerant from the cylinder as a vapor.
Refrigerant Charge
The amount of refrigerant charge is listed on the unit’s name-
plate. Refer to Carrier Publication, “GTAC2-5 Charging, Recov-
ery, Recycling and Reclamation Training Manual” and the fol-
lowing procedures.
Unit panels must be in place when unit is operating during the
charging procedure. If unit is equipped with a head pressure con-
trol device, bypass it to ensure full fan operation during charging.
NOTE: Charge checking and adjustments must be made while the
system is operating in Cooling only.
NO CHARGE
Use standard evacuation techniques for Puron (R-410A) refrig-
erant. After evacuating system, weigh the specified amount of
refrigerant.
LOW-CHARGE COOLING
Using Cooling Charging Charts (Fig. 21-24), vary refrigerant until
the conditions of the appropriate chart are met. Note the charging
charts are different from type normally used. Charts are based on
charging the units to the correct superheat for the various operat-
ing conditions. An accurate pressure gage and temperature sensing
device are required. Connect the pressure gage to the service port
on the suction line. Mount the temperature sensing device on the
suction line and insulate it so that outdoor ambient temperature
does not affect the reading. Indoor-air cfm must be within the nor-
mal operating range of the unit.
How To Use Cooling Charging Charts
Take the outdoor ambient temperature and read the suction pres-
sure gage. Refer to chart to determine what suction temperature
should be. If suction temperature is high, add refrigerant. If suc-
tion temperature is low, carefully recover some of the charge. Re-
check the suction pressure as charge is adjusted.
EXAMPLE:
Model 50TCQ*D17
Outdoor Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . 85°F (29°C)
Suction Pressure. . . . . . . . . . . . . . . . . . . . . . . . .140 psig (965 kPa)
Suction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . 55°F (13°C)
TXV SENSING
BULB
CLAMP
THERMAL EXPANSION
(TXV) VALVE
SENSING BULB INSULATION REMOVED FOR CLARITY

13
COOLING CHARGING CHARTS
Fig. 21 — Cooling Charging Chart — 50TCQ-D17 Circuit A
OVERCHARGING UNIT INCREASES THE RISK OF
NUISANCE HIGH PRESSURE SWITCH TRIPS
CAUTION DO NOT OVERCHARGE UNIT
IN HEATING MODE,
RECLAIM CHARGE AND RECHARGE UNIT PER NAMEPLATE
15 TON HEAT PUMP CHARGING CHART - R410A REFRIGERANT
(COOLING MODE) - CIRCUIT A
20
40
60
80
100
120
140
150 200 250 300 350 400 450 500 550 600
Compressor Discharge Pressure, (psig)
Outdoor Coil Leaving Temperature, (Degrees F)
Add Charge if Above the Curve
Remove Charge if Below the Curve
50HE501614 - A

14
Fig. 22 — Cooling Charging Chart — 50TCQ-D17 Circuit B
OVERCHARGING UNIT INCREASES THE RISK OF
NUISANCE HIGH PRESSURE SWITCH TRIPS
CAUTION DO NOT OVERCHARGE UNIT
15 TON HEAT PUMP CHARGING CHART - R410A REFRIGERANT
(COOLING MODE) - CIRCUIT B
20
40
60
80
100
120
140
150 200 250 300 350 400 450 500 550 600
Compressor Discharge Pressure, (psig)
Outdoor Coil Leaving Temperature, (Degrees F)
Add Charge if Above the Curve
Remove Charge if Below the Curve
IN HEATING MODE,
RECLAIM CHARGE AND RECHARGE UNIT PER NAMEPLATE
50HE501615 - A

15
Fig. 23 — Cooling Charging Chart — 50TCQ-D24 Circuit A
OVERCHARGING UNIT INCREASES THE RISK OF
NUISANCE HIGH PRESSURE SWITCH TRIPS
CAUTION DO NOT OVERCHARGE UNIT
20 TON HEAT PUMP CHARGING CHART - R410A REFRIGERANT
(COOLING MODE) - CIRCUIT A
20
40
60
80
100
120
140
150 200 250 300 350 400 450 500 550 600 650
Compressor Discharge Pressure, (psig)
Outdoor Coil Leaving Temperature, (Degrees F)
Add Charge if Above the Curve
Remove Charge if Below the Curve
IN HEATING MODE,
RECLAIM CHARGE AND RECHARGE UNIT PER NAMEPLATE
50HE501616 - A

16
Fig. 24 — Cooling Charging Chart — 50TCQ-D24 Circuit B
OVERCHARGING UNIT INCREASES THE RISK OF
NUISANCE HIGH PRESSURE SWITCH TRIPS
CAUTION DO NOT OVERCHARGE UNIT
20 TON HEAT PUMP CHARGING CHART - R410A REFRIGERANT
(COOLING CODE) - CIRCUIT B
20
40
60
80
100
120
140
150 200 250 300 350 400 450 500 550 600 650
Compressor Discharge Pressure, (psig)
Outdoor Coil Leaving Temperature, (Degrees F)
Add Charge if Above the Curve
Remove Charge if Below the Curve
IN HEATING MODE,
RECLAIM CHARGE AND RECHARGE UNIT PER NAMEPLATE
50HE501617 - A

17
Compressors
LUBRICATION
Compressors are charged with the correct amount of oil at the
factory.
REPLACING COMPRESSOR
NOTE: Only factory-trained service technicians should remove
and replace compressor units.
Compressors using Puron refrigerant contain a polyolester (POE)
oil. This oil has a high affinity for moisture. Do not remove the
compressor’s tube plugs until ready to insert the unit suction and
discharge tube ends.
COMPRESSOR ROTATION
NOTE: When the compressor is rotating in the wrong direction,
the unit makes an elevated level of noise and does not provide
cooling.
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:
4. Note that the evaporator fan is probably also rotating in the
wrong direction.
5. Turn off power to the unit.
6. Reverse any two of the three unit power leads.
7. Reapply electrical power to the compressor.
8. The suction pressure should drop and the discharge pres-
sure should rise which is normal for scroll compressors on
start-up.
9. Replace compressor if suction/discharge pressures are not
within specifications for the specific compressor.
FILTER DRIER
Replace the filter drier whenever refrigerant system is exposed to
atmosphere. Only use factory specified liquid-line filter driers
with working pressures no less than 650 psig (4482 kPa).
OUTDOOR FAN LOCATION
See Fig. 25.
1. Shut off unit power supply. Apply lockout/tag-out
procedures.
2. Remove condenser-fan assembly (grille, motor, and fan).
3. Loosen fan hub setscrews.
4. Adjust fan height as shown in Fig. 25.
5. Tighten setscrews to 84 in.-lb (9.5 Nm).
6. Replace condenser-fan assembly.
Fig. 25 — Outdoor Fan Adjustment
Troubleshooting Cooling System
Refer to Table 5 for additional troubleshooting topics.
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.
WARNING
FIRE, EXPLOSION HAZARD
Failure to follow this warning could result in death, serious
personal injury and/or property damage.
Never use air or gases containing oxygen for leak testing or for
operating refrigerant compressors. Pressurized mixtures of air
or gases containing oxygen can lead to an explosion.
CAUTION
INSTALLATION SITE DAMAGE
Failure to follow this caution can result in damage to equip-
ment location site.
R-410A refrigerant contains polyolester (POE) oil that can
damage the roof membrane. Caution should be taken to pre-
vent POE oil from spilling onto the roof surface.
The factory also recommends that the suction and discharge
lines be cut with a tubing cutter instead of using a torch to re-
move brazed fittings.
CAUTION
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution can result in premature wear and
damage to equipment.
Scroll compressors can only compress refrigerant if rotat-
ing in the right direction. Reverse rotation for extended
times can result in internal damage to the compressor.
Scroll compressors are sealed units and cannot be repaired
on site location.
CAUTION
EQUIPMENT DAMAGE
Failure to follow this caution can result in equipment damage.
Do not install a suction-line filter drier in liquid line. A liquid-
line filter drier designed for use with R-410A refrigerant is re-
quired on every unit.
CONDUIT
0.14 in. + 0.0 / -0.03

18
Table 5 — Heating and Cooling Troubleshooting
PROBLEM CAUSE REMEDY
Compressor and
Outdoor Fan
Will Not Start
Power failure. Call power company.
Fuse blown or circuit breaker tripped. Replace fuse or reset circuit breaker. Determine root cause.
Defective thermostat, contactor, transformer, control relay, or
capacitor. 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.
High pressure switch tripped. See problem “Excessive head pressure.”
Low pressure switch tripped. Check system for leaks. Repair as necessary.
Freeze-up protection thermostat tripped. See problem “Suction pressure too low.”
Compressor Will
Not Start But
Outdoor
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 or allow enough time for
internal overload to cool and reset.
Defective run/start capacitor, overload, start relay. Determine cause and replace compressor.
One leg of 3-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 outdoor coil or dirty air filter. Determine cause and correct.
Defective run/start capacitor, overload, or start relay. Determine cause and replace.
Defective thermostat. Replace thermostat.
Faulty outdoor-fan (cooling) or indoor-fan (heating) 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 (cooling). Reset thermostat.
Low refrigerant charge. Locate leak; repair and recharge.
Air in system. Recover refrigerant, evacuate system, and recharge.
Outdoor coil dirty or restricted. Clean coil or remove restriction.
Compressor
Makes Excessive
Noise
Compressor rotating in the wrong direction. Reverse the 3-phase power leads as described in Start-Up.
Excessive Head
Pressure
Dirty outside air or return air filter (heating). Replace filter.
Dirty outdoor coil (cooling). Clean coil.
Refrigerant overcharged. Recover excess refrigerant.
Air in system. Recover refrigerant, evacuate system, and recharge.
Condensing air restricted or air short-cycling. Determine cause and correct.
Head Pressure
Too Low
Low refrigerant charge. Check for leaks; repair and recharge.
Compressor scroll plates defective. Replace compressor.
Restriction in liquid tube. Remove restriction.
Excessive Suction
Pressure
High heat load. Check for source and eliminate.
Compressor scroll plates defective. Replace compressor.
Refrigerant overcharged. Recover excess refrigerant.
Suction Pressure
Too Low
Dirty air filter (cooling). Replace filter.
Dirty or heavily iced outdoor coil (heating). Clean outdoor coil. Check defrost cycle operation.
Low refrigerant charge. Check for leaks; repair and recharge.
Metering device or low side restricted. Remove source of restriction.
Insufficient indoor airflow (cooling mode). Increase air quantity. Check filter and replace if necessary.
Temperature too low in conditioned area. Reset thermostat.
Field-installed filter drier restricted. Replace.
Outdoor ambient below 25°F (cooling). Install low-ambient kit.
Outdoor fan motor(s) not operating (heating). Check fan motor operation.

19
CONVENIENCE OUTLETS
Two types of convenience outlets are offered on 50TCQ models:
non-powered and unit-powered. Both types provide a 125VAC/
15A Ground-Fault Circuit Interrupter (GFCI) duplex receptacle
behind a hinged waterproof access cover, located on the end panel
of the unit. See Fig. 26.
Fig. 26 — Convenience Outlet Location
Installing Weatherproof Cover
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. The cover must be installed at
unit installation. 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.
NOTE: DISCONNECT ALL POWER TO THE UNIT AND TO
THE CONVENIENCE OUTLET. Use approved lockout/tag-out
procedures.
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. 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).
4. Mount the weatherproof cover to the backing plate as shown
in Fig. 27.
5. Remove two slot fillers in the bottom of the cover to permit
service tool cords to exit the cover.
6. Check cover installation for full closing and latching.
Fig. 27 — Weatherproof Cover Installation
NON-POWERED TYPE
This type requires the field installation of a general-purpose
125VAC/15AC circuit powered from a source elsewhere in the
building. Observe national and local codes when selecting wire
size, fuse or breaker requirements and disconnect switch size and
location. Route 125VAC power supply conductors into the bottom
of the utility box containing the duplex receptacle.
UNIT-POWERED TYPE
A unit-mounted transformer is factory-installed to step-down the
main power supply voltage to the unit to 115VAC 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. 26.
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 the unit-mounted non-
fused disconnect or HACR breaker switch. This will provide ser-
vice power to the unit when the unit disconnect switch or HACR
switch is open. Other connection methods will result in the conve-
nience outlet circuit being de-energized when the unit disconnect
or HACR switch is open. See Fig. 28.
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.
GFCI
RECEPTACLE
LOCATION
TOP
WET LOCATIO NS
TOP
TOP
TOP
WET LOCATIONS
WE T LO CAT IO NS
COVER - WHILE-IN-USE
WEATHERPROOF
BASEPLATE FOR
GFCI RECEPTACLE
GASKET
GFCI RECEPTACLE
NOT INCLUDED

20
Fig. 28 — 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).
Test the GFCI receptacle by pressing the TEST button on the face
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.
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 Power Type
The factory fuse is a Cooper Bussmann1 Fusetron T-15, non-re-
newable 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.
HEAT PUMP CONTROLS
Central Terminal Board
The Central Terminal Board (CTB) is a large printed circuit board
that is located in the center of the unit control box. This printed cir-
cuit board contains multiple termination strips and connectors to
simplify factory control box wiring and field control connections.
Terminals are clearly marked on the board surface. See Fig 29.
The CTB contains no software and no logic. But it does include
seven configuration jumpers that are cut to configure the board to
read external optional and accessory controls, including the unit is
a heat pump. Jumpers JMP5, JMP6 and JMP7 are located in
notches across the top of the CTB. See Fig. 29. These jumpers are
factory cut on all heat pump units (see Table 6). Visually check
these jumpers to confirm that they have been cut.
Fig. 29 — Central Terminal Board (CTB)
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
Table 6 — Jumper Configuration
JUMPER CONTROL FUNCTION NOTE
JMP1 Phase Monitor
JMP2 Occupancy Control
JMP3 Smoke Detector Shutdown
JMP4 Remote Shutdown
JMP5 Heat Pump / Reheat 50TCQ default: Cut
JMP6 Heat Pump / Reheat 50TCQ default: Cut
JMP7 Heat Pump / Reheat 50TCQ default: Cut