Carrier 52S User Manual
52S
SERIES
SERVICE TECHNICIAN GUIDE
PACKAGED TERMINAL AIR CONDITIONERS
AND HEAT PUMPS
CONTENTS
INTRODUCTION
SUMMARY OF DANGERS, WARNINGS, AND CAUTIONS
GENERAL DISASSEMBLY
TO DISCONNECT POWER FOR CORD-CONNECTED UNIT
TO DISCONNECT POWER FOR PERMANENTLY
CONNECTED (HARDWIRED) UNITS
TO OPEN THE CONTROL BOX
TO REMOVE THE UNIT FROM THE WALL SLEEVE
TO REMOVE THE LATERAL DUCT EXTENSION, FOR
UNITS EQUIPPED WITH THE LATERIAL DUCT
ACCESSORY PACKAGE
TO ACCESS INDOOR-AIR SECTION COMPONENTS
TO ACCESS OUTDOOR-AIR SECTION COMPONENTS
GENERAL CLEANING
CLEANING AND SAFETY
TOOLS NEEDED
MONTHLY CLEANING
SEASONAL CLEANING
COMPRESSOR
COMPRESSOR TROUBLESHOOTING
BASIC HERMETIC COMPRESSOR ELECTRICAL
MEASUREMENTS
COMPRESSOR REPLACEMENT
.................................2,3
...........................4-9
...................4
.......................4
............................5
............................10-15
..........................10
.................................11
............................11
...........................13
..................................16-21
..................17
................................17
......................19
Page
...2
..4
........4
.......6
......8
HEATERS
COMMON CAUSES OF HEATER FAILURE
HEATER REMOVAL
OPERATING CONTROLS
DESCRIPTION OF SWITCH SETTINGS
NON-USER ADJUSTABLE SWITCHES
SEQUENCE OF OPERATION
COMPONENT OPERATION AND TROUBLESHOOTING
ELECTRICAL COMPONENTS REMOVAL AND
REPLACEMENT
FAN MOTOR
FAN MOTOR TROUBLESHOOTING
BASIC FAN MOTOR ELECTRICAL TESTS
FAN MOTOR REPLACEMENT
FIELD TEMPERATURE CHARTS
WIRING SCHEMATICS
MOST FREQUENT PTAC SERVICE QUESTIONS
......................................22,23
..............22
..............................22
.........................24-31
.................25
.................25
........................26
.................................30
...................................32-34
...................32
...............32
.......................34
....................35-50
...........................51-55
..........56
PTAC Customer Support Center
1
•
800•894•6449
....27
Page
52S
SERIES
INTRODUCTION
The focus of this manual is to provide basic information
on service procedures, safety, troubleshooting, cleaning, and component replacement for service technicians.
It is intended for use only by HVAC service technicians who have successfully completed instruction and received Type I Certification from the
U.S. Environmental Protection Agency.
The instructions in this manual are general in nature
and are not to be substituted for installation and service
instructions shipped with the unit. No attempt to install, operate, adjust, repair, or dismantle any equipment
should be made until the manufacturer’s instructions
are read and thoroughly understood by the service technician. Even equipment that seems familiar may have
specific model differences from year to year. Always
review manufacturer’s instructions.
The Model 52S packaged terminal air conditioner and
heat pump units are self-contained for installation
through the wall for individual room heating and cooling. The Model 52S polymer sleeve is permanently
fastened to the wall; the unit chassis slides out of the
sleeve to allow the service technician easy access. An
accessory louvered rear grille may be mounted on the
sleeve. Many accessories are offered to complement the
unit’s comfort control.
Before beginning any service procedures, it is important
to check the unit model number. Even units that seem
similar may have subtle differences that could affect
service procedures. The 52S units covered in this book
are the 52SC (Cooling Only model); the 52SE (Cooling
with Electric Heat model); and the 52SQ (Cooling, Electric Heat, and Heat Pump model).
Knowing which model is being serviced will help determine if the unit is performing at optimum levels. The
model number is located on the data information plate
beneath the front panel of the unit. The data information plate also lists voltage ranges and other important electrical information about the unit. To access
the data information plate, remove the front panel of
unit by grasping panel on each side and gently pulling
upward and out (Figure 1). See Figure 2 for model number nomenclature and Figure 3 for a sample data information plate.
SUMMARY OF DANGERS, WARNINGS,
AND CAUTIONS
The terms DANGER, WARNING, and CAUTION
have specific meanings that identify the degree of hazard. Typically in the HVAC industry, these specific
meanings are:
There is an immediate hazard which WILL result in
severe personal injury or death.
Hazards or unsafe practices which COULD result in
severe personal injury or death.
Potential hazards or unsafe practices which COULD
result in minor personal injury or equipment
damage.
FIGURE 1 — REMOVING FRONT PANEL
2
FIGURE 2 — MODEL NUMBER NOMENCLATURE
FIGURE 3 — SAMPLE DATA INFORMATION PLATE
3
52S
SERIES
GENERAL DISASSEMBLY
This section includes common procedures for disassembly and reassembly of 52S units. These instructions
are general in nature and include procedures the technician may be called upon to perform when accessing
certain components of the 52S unit.
It is important to carefully follow manufacturer’s instructions when disassembling or reassembling a unit for
cleaning, maintenance, or part replacement. When disassembling wiring, it is strongly recommended that
numbered stickers be attached to identify leads and terminals to aid in the reassembly process.Always review
safety procedures prior to the start of a job.
Prior to servicing electrical equipment, disconnect all
power to avoid electric shock! Never alter cord or plug
and do not use extension cords.
TO DISCONNECT POWER FOR CORDCONNECTED UNIT
1. Push OFF button.
2. Open the disconnect switch at main power supply.
Use proper Lockout and Tag procedures.
3. Unplug the unit service cord.
CONTROL
BOX
.
.
ACCESS
COVER
PLUG
ASSEMBLY
FIGURE 4 — DISCONNECTING PLUG
ASSEMBLY ON HARDWIRED UNITS
TO DISCONNECT POWER FOR
PERMANENTLY CONNECTED
(HARDWIRED) UNITS
1. Push OFF button.
2. Open the disconnect switch at main power supply.
Use proper Lockout and Tag procedures.
3. Remove screw from access cover and remove access cover.
Pull out the plug assembly and disconnect (see
4.
Figure 4).
TO OPEN THE CONTROL BOX
The control box is factory wired. To open the control
box, remove the 2 screws on the front of the control box
and lower the front hinged panel. See Figure 5.
TO REMOVE THE UNIT FROM THE
WALL SLEEVE
1. Remove the four, 1
cure the unit to the wall sleeve. There are 2 screws
on each side (Figure 6).
2. Grasp the sides of the unit and slide it from the sleeve.
The chassis weighs between 110 and 150 pounds.
Take proper safety precautions to avoid personal injury when lifting and moving the chassis.
3
⁄4-in. mounting screws that se-
FIGURE 5 — OPEN CONTROL BOX
The unit basepan may have water in it. Tilt the unit
back slightly when removing it from the sleeve to
drain some of the water into the sleeve.
FIGURE 6 — UNIT TO WALL SLEEVE
MOUNTING SCREWS
4
TO REMOVE THE LATERAL DUCT
EXTENSION, FOR UNITS EQUIPPED
WITH THE LATERAL DUCT ACCESSORY
PACKAGE
1. Remove the front panel as shown in Figure 1.
2. Remove the four 1
chassis to the wall sleeve (see Figure 6). There are
2 screws on each side.
3. Remove the 2 screws that secure the lateral duct ex-
tension to the top of the lateral duct adapter as shown
in Figure 7.
4. Locate and remove the 2 screws that secure the
lateral duct extension to the bracket flange as shown
in Figure 8.
5. Carefully slide the chassis away from the extension
duct and remove from the sleeve (as shown in
Figure 9).
3
⁄4-in. screws that secure the
FIGURE 7 — DUCT EXTENSION SCREWS
The unit basepan may have water in it. Tilt the unit
back slightly when removing it from the sleeve to
drain some of the water into the sleeve.
The chassis weighs between 110 and 150 pounds.
Take proper safety precautions to avoid personal injury when lifting and moving the chassis.
FIGURE 8 — BRACKET FLANGE SCREWS
FIGURE9—PARTIAL REMOVAL OF CHASSIS
FROM WALL SLEEVE
5
52S
SERIES
TO ACCESS INDOOR-AIR SECTION
COMPONENTS
n DISASSEMBLING THE LATERAL DUCT
ADAPTER, FOR UNITS EQUIPPED WITH THE
LATERAL DUCT ACCESSORY PACKAGE
Remove the lateral duct adapter end cap, shown in
1.
Figure 10, by removing the two
2. Remove the adapter top panel by removing one screw
at each end of unit as shown in Figure 11. Rotate the
front of the panel up and back and lift free.
3. Rotate and lift the air baffle out of the unit. See
Figure 12.
4. Remove the 2 screws holding the duct adapter to the
chassis discharge air opening flanges, as shown in
Figure 13, and remove the duct adapter.
1
⁄2-in. screws
FIGURE 12 — REMOVING THE AIR BAFFLE
FIGURE 10 — WALL SLEEVE, DUCT ADAPTER,
AND EXTENSION LOCATION
(RIGHT-HAND EXTENSION)
FIGURE 11 — DISCHARGE PLENUM ASSEMBLY
FIGURE 13 — REMOVING THE DUCT ADAPTER
6
n TO REMOVE THE AIR DISCHARGE GRILLE
L
1. Remove the 2 screws on each end of the air discharge
grille as shown in Figure 14.
2. Lift and rotate back the bottom edge of the discharge
grille and remove it.
n TO REMOVE THE ALUMINUM TOP PANEL
— Remove one screw from each end of the aluminum
top panel (located on the underside of the panel) as shown
in Figure 15. On the left side of the unit, remove the
screw closest to the side of the unit.
FIGURE 14 — REMOVING AIR DISCHARGE GRILLE
n TO REMOVE THE TOP COVER — Remove the screw
located in the middle of the top cover and remove the
cover. See Figure 16.
FIGURE 15 — ALUMINUM TOP PANEL
FIGURE 16 — TOP COVER SCREW
TOP PANE
SCREW
7
52S
SERIES
n TO REMOVE THE DISCHARGE DECK
1. Remove the 2 discharge deck screws shown in
Figure 17. Also remove the screw located at the top
left corner of the outdoor coil tube sheet.
2. Gently pull the left side panel out and lift the
end of the discharge deck that the screws were removed from, up and forward, to remove.
TO ACCESS OUTDOOR-AIR SECTION
COMPONENTS
n TO REMOVE THE GUSSET
1. Remove the 2 screws that secure the gusset to the
partition.
2. Remove the screw that secures the gusset to the
plastic condenser orifice and remove the gusset.
See Figure 18.
DISCHARGE
SCREWS
DECK
FIGURE 17 — DISCHARGE DECK REMOVAL
CONDENSER
ORIFICE
GUSSET
PARTITION
n TO DETACH THE CONDENSER ORIFICE FROM
THE CONDENSER COIL — Using a flat head screw
driver, gently pry the plastic condenser orifice tabs away
from both condenser coil tube sheets and pull the condenser orifice away as shown in Figure 19.
FIGURE 18 — GUSSET REMOVAL
COIL
ASSEMBLY
COIL
FINS
COIL
MOUNTING
SCREWS
CONDENSER
ORIFICE
CONDENSER
ORIFICE TABS
BASEPAN
FIGURE 19 — REMOVING CONDENSER ORIFICE
8
STATOR
n TO REMOVE THE STATOR — After pulling the top
of the condenser orifice away from the condenser coil,
grasp the top of the stator and slide it up and out of the
stator track. See Figure 20.
CONDENSER
ORIFICE
CONDENSER
COIL
FIGURE 20 — REMOVING STATOR
9
52S
SERIES
GENERAL CLEANING
Maintaining proper performance of 52S systems
(Figure 21) requires conscientious cleaning and care of
components. Specific components require periodic cleaning and/or replacement, including the following:
COMPONENT CLEANING SCHEDULE
Indoor Air Filter Monthly
Vent Air Filter Monthly
Indoor Coil Seasonally
Indoor Fan Seasonally
Outdoor Coil Seasonally
Before cleaning, servicing, performing maintenance,
or removing the chassis from the wall sleeve, disconnect all power to the unit to avoid the possibility of
electrical shock and personal injury. Only trained
and qualified service personnel should perform
installation and service procedures on these units.
Untrained personnel may perform basic maintenance
tasks such as cleaning and replacing filters. Refer to
General Disassembly section of this manual for
proper procedures to disconnect power to 52S units.
CLEANING AND SAFETY
Before starting to clean a unit, read the instructions
thoroughly and gather the necessary tools for the job.
Review all safety information on unit and in literature.
Consider the following safety issues before
beginning:
• New and unfamiliar tasks should be performed
under the supervision of an experienced service
technician.
• Personal protective equipment, such as safety glasses
and work gloves, should be used.
• The floor around the work area should be clean and
free of debris.
• The 52S unit weighs up to 150 pounds. Use a lifting
device or ask for assistance if the unit must be moved.
• Make sure tools are the correct tools for the job,
and that they are working properly and in good
condition.
ON
OFF
WALL SLEEVE
CHASSIS
FRONT COVER
FIGURE 21 — FRONT PANEL, CHASSIS, AND SLEEVE
10
TOOLS NEEDED
The following list includes the recommended tools, devices, and cleaning solutions for use in cleaning the 52S
unit components.
Vacuum Cleaner with Crevice Tool Attachment,
Lifting Device (or another person for assistance)
Trigger Spray Extension Tube (Part No. P9029000)
Vent Air Filter Replacement (Part No. 52SQ500204)
Condenser Coil Cleaning Solution (Part No. P9020501)
Evaporator Coil Cleaning Solution (Part No. P9021001)
3% Solution of Hydrogen Peroxide in Spray Bottle
or Soft Plastic Bristle Brush
Mild Household Detergent
Phillips Head Screwdriver
5
⁄16-in. Nut Driver
Flat Head Screw Driver
Tank Sprayer (Part No. P9021001) or
Compressed Air Tank
Clean Water Supply
Indoor Air Filter Replacement
(Part No. AIR-FILTER-25PAK)
9.5-in. by 9.5-in. Piece of Clean Cardboard
Clean Cloth
Safety Glasses
Protective Gloves
MONTHLY CLEANING
n AIR FILTERS — The indoor and vent air filters should
be cleaned once per month. Filters that are not cleaned
become clogged and will restrict airflow. This may lead
to major component damage. If a filter becomes torn, has
holes, or other damage, replace it with a new one. Replacement filters are available through Carrier Finished
Goods and Carrier Replacement Component Division.
n CLEANING THE INDOOR AIR FILTER — Remove
the indoor air filter as follows:
1. Remove the front panel to access the indoor air filter.
To remove front panel, grasp panel firmly near the
top of each side. Lift upward and pull forward. It is
not necessary to use excessive force. See Figure 1.
2. To remove the indoor air filter, gently grasp the
2 filter tabs, push down, and pull out. See Figure 22.
Once the indoor air filter has been removed, use a
vacuum cleaner, or a soft bristle brush and a small
amount of mild dish detergent to gently wash the
filter. If detergent is used, remove detergent residue with
a gentle, clean water stream. Let the filter air dry. Be
sure to reinsert the filter into the unit.
FIGURE 22 — REMOVING FILTER
n REPLACING THE INDOOR AIR FILTER — Access
and remove indoor air filter as detailed above in Cleaning the Indoor Air Filter. Use a filter replacement with
the Carrier Part No. AIR-FILTER-25PAK, available
through Carrier Finished Goods and Carrier Replacement Component Division.
11
52S
SERIES
n CLEANING THE VENT AIR FILTER
1. Remove the unit chassis from wall sleeve as described
in the General Disassembly section of this manual.
See Figure 6.
2. Swing open vent door. The filter is located directly
behind the vent door. See Figure 23.
3. Remove the vent air filter by gently pushing on the
filter slot.
Once the vent air filter is removed, it may be cleaned
using either a vacuum cleaner, or a soft bristle brush
and a small amount of mild dish detergent. If detergent is used, remove detergent residue with a gentle,
clean water stream. Let the filter air dry. Be sure to reinsert the filter into the unit.
n REPLACING THE VENT AIR FILTER
Access and remove the vent air filter as detailed above
in Cleaning the Vent Air Filter. Use a filter replacement
with the Carrier Part No. 52SQ500204, available
through Replacement Components Division.
n CHASSIS
As-needed cleaning of the unit’s exterior surfaces
(Figure 24) optimizes the unit’s appearance and removes
particles that may enter the air system. The 52S units
are built to resist corrosion. The indoor front panel
and wall sleeve are created from non-metallic compounds
that do not rust. Additional corrosion protection may
be factory installed on the partition, control box, and outside coil for use in highly corrosive environments. Mild
detergents reduce electrostatic charges on plastic sections on the grille and are good cleaners. Use such detergent cleaners sparingly.
Use a clean cloth or brush to gently wipe exterior surfaces. Be careful not to push dirt or other fibers into the
unit’s interior.Accessible sleeve surfaces should also
be wiped clean.
VENT
FILTER
VENT
DOOR
FIGURE 23 — ACCESSING VENT AIR FILTER
FIGURE 24 — UNIT FRONT PANEL AND SLEEVE
12
SEASONAL CLEANING
n ACCESSING THE INDOOR AND OUTDOOR
COILS — The minimum cleaning recommendation for
indoor and outdoor coils is once per season. To access
the coils for a thorough cleaning, it is necessary to
remove the Air System. To accomplish this task, perform the following steps:
1. DISCONNECT ALL POWER TO UNIT!
2. Remove the unit chassis from the sleeve as described
in the General Disassembly section of this manual.
See Figure 6.
3. Remove each side angle from unit with a
driver. See Figure 25.
4. Locate and disconnect wires from the compressor.
Label each wire for easy reassembly.
For compressors that are known to be damaged: Remove refreigerant prior to disconnecting
compressor wires. Damaged hermetic compressor terminals may become loose and eject from the compressor. Wear safety glasses and keep your face away
from the area above the terminals when removing
compressor wires.
5. For Heat Pump Units — Disconnect the wire plug
on the reversing valve and carefully remove the outdoor thermostat capillary from the outdoor coil.
6. With a
8 screws mounting the fan section to the chassis. See
Figures 26 and 27.
5
⁄16-in. nut driver, locate and remove the
7. Using a flat head screw driver, gently pry the plastic
condenser orifice tabs away from both outdoor coil
tube sheets and pull the condenser orifice away as
shown in Figure 19. See GENERAL DISASSEMBLY
section.
8. Carefully remove the fan section from the chassis
by lifting fan section straight up and out. The fan
deck is awkward; 2 people may be needed for its
removal.
5
⁄16-in. nut
9. Remove the stator from the outdoor coil. See
GENERAL DISASSEMBLY section. After cleaning,
reassemble by reversing steps1-8.
IMPORTANT: During reassembly of the fan section,
carefully align the rubber seal around the tubing where
it passes through the partition.
FIGURE 25 — SIDE ANGLE SCREWS
FIGURE 26 — PARTITION FLANGE SCREWS
FIGURE 27 — FAN SECTION SCREW LOCATIONS
13
52S
SERIES
n CLEANING THE INDOOR AND OUTDOOR COILS
Coil fins are sharp and may cut hands. Wear heavy
protective gloves when cleaning coils.
1. Use a vacuum cleaner or soft bristle brush to remove
surface fibers and dirt from each of the faces of the
coil. Both the inner and outer surfaces of the coils
must be cleaned. It is important to apply the tool in
the same direction of the fins, not against them.
Applying the tool against the fins may cause damage
(fin edges may bend over).
2. With a tank sprayer or a trigger spray extension tube,
spray coil cleaning solution evenly across the coils,
making sure coils are thoroughly saturated. See
Figure 28. Refer to instructions on the cleaning solution containers for best results. Do not use a high
pressure sprayer.
3. Rinse the coils thoroughly with low-velocity, clean
water.
4. Repeat steps 2 and 3.
5. Drain water and cleaning solution that may have
collected in the basepan during the cleaning process by carefully tilting the chassis. This allows
excess water to flow out of the overflow notches.
FIGURE 28 — CLEANING THE COILS
Do not set unit on end to drain water from basepan,
or at any other time. Oil will drain from the compressor sump, which could cause compressor failure.
6. Thoroughly clean the basepan and drain passages
by rinsing with clean water. Be sure all debris is removed from the drain valve. See Figure 29.
7. Allow unit components to air dry before reassem-
bling the unit. Once dry, reassemble by reversing
Steps1-9from the Accessing Indoor and Outdoor
Coils section.
n ACCESSING THE INDOOR FAN AND INDOOR
FAN SCROLL — Dried debris and build-up on the
blower wheel and blower scroll can reduce the efficiency
of the unit. To properly access the indoor fan and indoor fan scroll for cleaning, refer to the GENERAL
DISASSEMBLY section under To Access Indoor-Air
Section Components on page 6.
FIGURE 29 — BASEPAN SECTION
14
n CLEANING THE INDOOR FAN AND FAN
SCROLL — Once the indoor fan wheel and the indoor
fan scroll have been accessed, proceed with the cleaning
instructions detailed below:
1. Insert a piece of 9.5-in. by 9.5-in. cardboard between
the blower wheel and the opening in the blower scroll
to prevent fungus and other debris from falling into
the coil.
2. Bend a soft, spiral wound, long bristle brush, to con-
form to the inner curve of the blower wheel blades.
See Figure 30.
3. Insert the brush into every blower wheel blade and
gently brush out dried material.
4. Clean the walls of the blower scroll by carefully brush-
ing with the bristle brush. Vacuum loose debris that
may have fallen into the bottom of the scroll during the cleaning process.
5. Use the spray bottle to spray the blower wheel blades
and the inner surface of the blower scroll with a 3%
solution of hydrogen peroxide to kill any fungus
spores. Wipe up excess solution in the bottom of the
blower scroll with a clean cloth. See Figure 31.
6. Reassemble components by reversing the steps used
to disassemble the unit as detailed in the GENERAL
DISASSEMBLY section under To Access Indoor-
Air Section Components.
n ACCESSING THE HEATER ASSEMBLY — To access
the heater assembly for cleaning, perform the following steps:
1. DISCONNECT ALL POWER TO THE UNIT.
2. Remove the unit front panel, the discharge air grille,
and the discharge air deck as described and shown
in Figure 1 and the GENERAL DISASSEMBLY
section.
3. Once the discharge air deck is removed, the heater
assembly is accessible.
n CLEANING THE HEATER ASSEMBLY — Once the
heater assembly is accessed, use compressed air to blow
off any dust that has accumulated on the heater coils.
Do not direct the air at the bi-metal discs of the temperature limit switches. Reassemble the unit by reversing
Steps1-3.
FIGURE 30 — CLEANING INDOOR FAN
AND FAN SCROLL
Do not touch the heater coils or the temperature limit
switches. Touching or depressing the bi-metal discs
on the temperature limit switches may affect the set
point or cause the secondary temperature limit
switch to electrically open, requiring it to be replaced.
FIGURE 31 — SPRAYING BLOWER WHEEL BLADES
15
52S
SERIES
COMPRESSOR
A cutaway view of the rotary compressor with key components labeled is shown in Figure 32. The motor stator is rigidly attached to the compressor shell. The rotor
is pressed onto the eccentric shaft, which is supported
by 2 bearings. Both the discharge valve and discharge
muffler are attached to the motor bearing. The pump
DISCHARGE TUBE
SUCTION INLET
SUCTION MUFFLER/
ACCUMULATOR
bearing provides a thrust surface for the shaft and the
rolling piston. Compressed gas is separated from the
suction gas by the vane. Discharge gas pressure and the
vane spring keep the vane in contact with the rolling
piston.
SHELL
STATOR
ECCENTRIC SHAFT
ROTOR
PISTON
VANE
OIL TUBE
MOTOR BEARING
DISCHARGE MUFFLER
DISCHARGE VALVE
CYLINDER
PUMP BEARING
MOUNTING PLATE
FIGURE 32 — ROTARY COMPRESSOR COMPONENTS
16
The rotary compression process (Figure 33), starts at
top dead center as shown in (1). Suction gas flows
through the suction inlet and into the cylinder area. As
the shaft rotates through 90 degrees, the rolling piston moves to position A as shown in (2). The suction volume is now the area defined by point A and the tip of
the vane. Gas in the remaining volume has been compressed above suction pressure. After another 90 degrees
of shaft rotation, the rolling piston has moved to position B as shown in (3). Both the compressed gas and
suction gas volumes are now equal. Another 90 degrees
of shaft rotation is shown in (4). Compressed gas has
reached a pressure sufficient to open the discharge valve,
and flows from the cylinder into the compressor shell.
After another 90 degrees of shaft rotation, the entire
process begins again. Continuous suction and discharge
allows for a smooth compression process.
The rolling piston is not in actual contact with the cylinder wall, vane, or bearing faces. Hydrodynamic
sealing prevents leakage from the compressed gas volume to the suction volume via these paths. Precise control of machining tolerances, surfaces, finishes, and
assembly clearances is critical to achieve high efficiency
performance. In addition, the line contact between the
vane tip and the rolling piston requires careful selection
and control of materials to provide wear resistance and
reliable long-term operation.
COMPRESSOR TROUBLESHOOTING
Refer to Figure 34 for a basic compressor troubleshooting chart.
BASIC HERMETIC COMPRESSOR
ELECTRICAL MEASUREMENTS
There are 2 basic electrical tests for hermetic compressors that will determine the electrical state of the motor. The first test requires checking the electrical
resistance of each of the electrical motor windings. The
second test requires checking the electrical resistance
of each of the electrical motor windings to ground. These
tests may be accomplished by performing the following
steps:
1. DISCONNECT ALL POWER TO THE UNIT.
2. Remove the unit chassis from the sleeve as detailed
in the GENERAL DISASSEMBLY section.
3. Open the control box as detailed in the GENERAL
DISASSEMBLY section, then locate, label, and remove the 3 compressor wires from the following locations: the RUN wire (BLACK) from the capacitor,
the START wire (BLUE) from the capacitor. The third
wire, COMMON wire (YELLOW) may be connected
to one of the following locations: for SC units the
wire is on the indoor thermostat, for SE Remote
Control Units the wire is on the indoor frost thermostat, for all other SE Units the wire is located
on the push button switch, for ALL SQ Units the
wire is on the outdoor frost thermostat.
FIGURE 33 — ROTARY COMPRESSOR
COMPRESSION PROCESS
For compressors that are known to be damaged: Remove refrigerant prior to disconnecting com-
pressor wires. Damaged hermetic compressor
terminals may become loose and eject from the compressor. Wear safety glasses and keep your face
away from the area above the terminals when removing compressor wires.
4. To measure the resistance between the windings of
the compressor motor, use a volt-ohmmeter set to
the lowest ohm reading level then read and record
the resistance between the RUN and START, START
and COMMON, and RUN and COMMON wires.
See Figure 35. The typical resistance readings will
be about 4, 3, and 1 ohms respectively. The smaller
values should add to equal the larger value. If this is
not true then the compressor is likely shorted winding to winding.
NOTE: The rotary compressor has the compressor overload located under the terminal cover. If the overload
is open it can show ohm readings that are infinite. The
unit should be off for at least an hour to give this overload time to reset if it is open.
17
Loading...