Troubleshooting package-type air-conditioning units(PACU) / commercial refrigeration equipment (CRE)

COMPETENCY BASED LEARNING MATERIAL

Sector:
HEATING, VENTILATING, AIR-CONDITIONING AND REFRIGERATION (HVAC/R)

Qualification:

RAC Servicing (PACU/CRE) NC III

Unit of Competency:

Service and Maintain Package-Type Air-Conditioning Units
(PACU)/Commercial Refrigeration Equipment (CRE)

Module Title:

Troubleshooting Package-Type Air-Conditioning Units
(PACU)/Commercial Refrigeration Equipment (CRE)

Technical Education and Skills Development Authority

East Service Road, South Superhighway, Taguig, Metro Manila

TABLE OF CONTENTS

SYSTEM’S COOLING CAPACITY BELOW NORMAL...................................... 1

LEAK TESTING USING ELECTRONIC LEAK
DETECTOR...................................................................................................... 2

PERFORM LEAK TESTING IN A PACKAGE-TYPE AIR
CONDITIONING UNIT AND COMMERCIAL
REFRIGERATION EQUIPMENT ...................................................................... 7

FILTER DRIER ................................................................................................. 8

REPLACE FILTER DRIER................................................................................ 9

MOTOR FUNDAMENTALS ............................................................................ 14

FAN MOTORS................................................................................................ 21

IDENTIFY FAN MOTOR TERMINALS............................................................ 25

COMPRESSOR MOTOR ELECTRICAL CONNECTION ................................ 30

WIRING OF PERMANENT SPLIT CAPACITOR
MOTOR CONNECTION ................................................................................. 37

WIRING OF CAPACITOR START CAPACITOR RUN
MOTOR CONNECTION ................................................................................. 39

WIRING OF CAPACITOR START INDUCTION RUN
MOTOR CONNECTION ................................................................................. 41

HERMETIC MOTOR COMPRESSOR ............................................................ 43

IDENTIFYING HERMETIC COMPRESSOR TERMINAL ................................ 47

DETERMINING HERMETIC COMPRESSOR
TERMINAL ..................................................................................................... 49

TESTING COMPRESSOR MOTOR WINDING............................................... 50

REPLACING COMPRESSOR MOTOR (HERMETIC) .................................... 53

COMPRESSOR MOTOR USED IN PACKAGE AIR
CONDITIONING UNIT AND COMMERCIAL
REFRIGERATION EQUIPMENT .................................................................... 56

OPEN DRIVE COMPRESSOR ....................................................................... 62

REPLACE COMPRESSOR MOTOR (OPEN-DRIVE)..................................... 64

TROUBLESHOOTING CHART: MECHANICAL
TROUBLE ...................................................................................................... 70

TROUBLESHOOTING PACU/CRE: MECHANICAL
TROUBLE ...................................................................................................... 76

TROUBLESHOOTING UNIT WHEN COMPRESSOR
FAILS TO START ........................................................................................... 77

TROUBLESHOOTING CHART ELECTRICAL
TROUBLES .................................................................................................... 80

TROUBLESHOOTING PACU/CRE: ELECTRICAL
TROUBLES .................................................................................................... 83

Information Sheet 1

System’s Cooling Capacity Below Normal

Refrigeration and air conditioning systems are devices that are expected to produce
conditioned air above room temperature. Once a refrigerator or air conditioning system, fails
to produce cool air, we can assume that it is cause by a poor circulation of refrigerant across
the system or lack of refrigerant.

Symptoms of these defects are the following:

 Frosting evaporator for air conditioner
This is due to the corresponding temperature of pressure is freezing point of

water in the evaporator side.

 Not completely covered with frost for Frost building-up at
refrigeration the evaporator
The amount of liquid refrigerant is
limited in the evaporator component.

 Full load current below normal based on
compressor nameplate.
This is cause by the low pressure
load of the compressor motor making it
dissipate lesser power.

 Condenser unit temperature below normal
Vapor is directly proportional to temperature. If the pressure is low, the system

is expected to have a low temperature vapor.

 Pressure in high side below normal
Vapor is directly proportional to temperature. If the pressure is low, the system

is expected to have a low temperature vapor.

 Low side pressure below normal
Vapor is directly proportional to temperature. If the pressure is low, the system

is expected to have a low temperature vapor.

 Filter drier temperature below normal
Vapor is directly proportional to temperature. If the pressure is low, the system

is expected to have a low temperature vapor.

TESDA-GOTEVOT 1
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Operation Sheet 1

Leak Testing Using Electronic Leak Detector

Objectives: At the end of this activity, the learner/trainee should be able to:
o Test leak the system
o Practice safety precaution and proper housekeeping

Materials, Tools and Equipment:

Materials:

o Clean cloth - 1 pc

o Compressor oil of the same specification

o Soap suds

Tools:

o Adjustable wrench - 1 set

o Ratchet wrench - 1 set

o Double ended spanner - 1 set

o Small paint brush - 1 set

o Charging lines - 1 pc

Equipment:

o Service cylinder w/ appropriate refrigerant - 1 cylinder

o Service cylinder containing nitrogen - 1 cylinder

Instrument:

o Electronic leak detector - 1pc

o Gauge manifold - set

Personal Protective Equipment

o Goggles

o Mask

o Gloves

* - Item is optional

Introduction:
Leak testing- is the process of locating refrigerant leaks with in the refrigerant

system. It can be done through the use of halide torch, electronic leak detector soap suds or
bubbles.

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Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
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Operation Sheet 1

Procedure:
Make sure that before you perform this activity, you are wearing appropriate personal

protective equipment.
1. Prepare the system

a. Install gauge manifold set into
the system.

b. Place high and low
compressor valve in cracked
position.

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Operation Sheet 1

c. Place high and low side
manifold shut off valve in
closed position.

d. Note down the pressure in the
system to determine the
refrigerant in the system.

Caution: See that a minimum
of 50-55 P. S. I. G. is needed
for leak test.

If the system pressure is below than 50-
55 P. I. S. G. or new piping system, is
installed it needs to be charged first
(follow steps e to h).

e. If there is no refrigerant in the
system then attach the center
line of the gauge manifold to a
refrigerant cylinder.

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Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
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Operation Sheet 1

f. Open the refrigerant in the
system service cylinder valve,
and charge the refrigerant into
the system till the pressure
reads 50-55 P. S. I. G. in the
low side and high side gauge.

Note: Make sure that the solenoid
valve is energized to allow
refrigerant to pass throughout the
system. Where the sign glass and
the pressure gauge reading.
g. When the solenoid valve is

energized, cause the hand
valve of the gauge manifold.
h. Close the service valve of the
refrigerant cylinder.
Note: Oil traces in the fittings or pipes
usually indicates leaks
2. Turn on the electronic leak detector

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Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
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Operation Sheet 1

3. Check for leak by moving the search
nozzle under and around all joint
connections in the systemincluding
compression shaft seal.

4. Observed the change in sound of the
electronic leak detector

a. Beeping sound indicates no leak
b. Continous beeping sound indicates

leak
5. If the location of the leak cannot be

detected, use the soap suds method
to pinpoint the actual location of leak.

6. Let your instructor check your work
7. Perform house keeping

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Assignment Sheet 1

Objectives: Perform Leak Testing in a Package-Type Air
Conditioning Unit and Commercial Refrigeration
Equipment

At the end of this activity, the learner/trainee should be able to:
o Test leak the system
o Locate leaks in a refrigeration and air conditioning system

Direction: Test a package-type air conditioning unit and commercial refrigeration equipment
for leaks. Record your findings in the form below.

Package-Type Air Conditioning Unit

Test Points Is there a leak?
Yes No

1

2

3

4

5

Commercial Refrigeration Equipment

Test Points Is there a leak?
Yes No

1

2

3

4

5

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Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Information Sheet 2

Filter Drier

Liquid Line Filter Drier

Water in a refrigeration system can
cause freezing and blocking of the expansion
valve, corrosion of metal and chemical
damage to electrical insulation. The system
should be thoroughly evacuated and dried
before charging with refrigerant, but even
then a filter/drier should be installed in the
liquid refrigerant line between the condenser
or liquid receiver and expansion valve. The
filter drier is a device that removes foreign
matter from the refrigerant. This foreign
matter can be dirt, flux, from soldering, solder
beads, fillings, moisture, parts and acid
caused by moisture. It has a very fine mesh
screen and contains disinfectants such as
silica gel or activated alumina which removes
foreign materials and absorbs moisture,
respectively.

Suction Line Filter Drier

Filter driers are often mounted in the
suction line to prevent foreign particles of
over 5 microns in size as well as acids,
sludge and moisture, from entering the
compressor. It is used to protect the
compressor.

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Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
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Job Sheet 1

Replace Filter Drier

Objectives: At the end of this activity, the learner/trainee should be able to:
o Pump down the unit
o Recover refrigerant
o Replace filter drier
o Leak test the unit
o Charge the unit
o Practice safety and proper housekeeping

Materials, Tools and Equipment:

Materials: - 1 pc
o Filter drier - 1 cylinder
o Refrigerant
- 1 set
Tools
o Wrenches - 1 unit
- 1 unit
Instrument
o System analyzer - 1 unit
o Leak detector - 1 unit

Equipment
o Vacuum pump
o Recovery/recycling Machine

Personal Protective Equipment - 1 pc
o Goggles - 1 pair
o Globes - 1 pc
o Mask

* - Item is optional

Introduction:

The filter drier is a device used in a refrigerant line to remove moisture. It is a practice
to replace filter drier, every time that a system is to be re-charged with refrigerant. It is also a
must to replace the filter drier with the same specification in order to eliminate the presence
of contaminants and moisture within the system.

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Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Job Sheet 1

Procedure:
Make sure that before you perform this activity, you are wearing appropriate personal

protective equipment.

2. Pump down the unit. See to it that
the service valve in the liquid
receiver is front seated.

3. Recover remaining refrigerant from
liquid line, evaporator and suction
line.

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Job Sheet 1

4. Remove defective filter drier.

5. Install appropriate and new set of
filter drier.

6. Purge the system and test for leak.
Make sure that after purging the
liquid receiver valve is returned to
close position.

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Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
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Job Sheet 1

7. Vacuum the unit till the gauge
reading reach perfect vacuum
(approximately 29 inch of mercury)

8. After vacuuming close the two valves
of the system analyzer.

9. Disconnect the center hose from the
vacuum pump and transfer to
refrigerant tank cylinder.

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Job Sheet 1

10. Open refrigerant cylinder valve and
purge the center hose. Then after
purging make sure that the fittings
are tightened.

11. Open all valves to its normal
operation

12. Run the unit and observe its
operation. Add refrigerant if needed.

13. Have your job check by your
instructor

14. Perform proper housekeeping

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Information Sheet 3

Motor Fundamentals 14

as discussed in http://cipco.apogee.net/mnd/mddovr.asp

Principles of Magnetism

Magnetism is the force that
creates rotation for a motor to
operate. The poles of a permanent
magnet are connected by magnetic
lines of force. The principle of
magnetism states that unlike poles
are attracted to one another while like
poles repel. AC motors operate on
this principle.

When two bar magnets come
into close proximity, the resulting
attraction and repulsion create force.
The magnet on the left is stationary
and cannot move. The one on the
right is free-turning and rotates. As
the "North" pole of the rotating
magnet moves away from the like
pole of the stationary magnet, the
"South" pole of the rotating magnet is
attracted towards the opposite pole of
the stationary magnet. Since unlike
poles attract, the turning magnet
rotates until the "N" and "S" poles
come together. When this occurs,
both magnets are satisfied and no
further action will occur.

Principles of Electromagnets

Electromagnets are similar to
permanent magnets, but produce
much stronger magnetic fields.
Electric motors require this extra
capacity.

To make an electromagnet, an

TESDA-GOTEVOT
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Information Sheet 3

iron rod is wrapped with insulated
wire. The rod is called a "core".

Electric current flows through
the wire when it is connected to a
battery. This current magnetizes the
iron core. Once magnetized, the core
has both "N" and "S" poles. The poles
of an electromagnet can be reversed
by changing the direction of current
flow.

When one or both ends of the
wire at the battery are disconnected,
current flow stops and the core loses
its magnetism.

Alternating current changes
directions on its own, causing the
poles in the electromagnet to switch.

How electric motors work 15

Electric motors function on the
principle of magnetism; where like
poles repel, and unlike poles attract.

In a simple motor, a free-
turning permanent magnet is
mounted between the prongs of an
electromagnet. Since magnetic forces
travel poorly through air, the
electromagnet has metal shoes that
fit close to the poles of the permanent
magnet. This creates a stronger more
stable magnetic field. (The
electromagnet functions as the stator,
and the free-turning magnet is the
rotor.) Fluctuating polarity in the
electromagnet causes the free-
turning magnet to rotate. The poles
are changed by switching the
direction of current flow in the
electromagnet.

TESDA-GOTEVOT
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Information Sheet 3

The direction of current flow
can be changed in one of two ways.
In a DC motor, connections must be
interchanged at the battery. AC
current oscillates on its own.

The stator in an AC motor is a
wire coil, called a stator winding. It's
built into the motor. When this coil is
energized by AC power, a rotating
magnetic field is produced.

When a magnetic field comes
close to a wire, it produces an electric
current in that wire. This is called
induction. In induction motors, the
induced magnetic field of the stator
winding induces a current in the rotor.
This induced rotor current produces a
second magnetic field necessary for
the rotor to turn.

Induction motors are equipped with 16
squirrel rotors, which resemble the
exercise wheels often associated with
pet rodents like gerbils. Several metal
bars are placed within end rings in a
cylindrical pattern. Because the bars
are connected to one another by
these end rings, a complete circuit is
formed within the rotor.

Consider this close-up of a 2-
pole stator and one of its rotor bars.
Alternating current flowing in the
stator causes the poles to change
rapidly, from north to south and back
again. If the rotor is given a spin, the
bars cut the stator lines of force. This
causes current flow in the rotor bar.
This current flow sets magnetic lines
of force in circular motion around the
rotor bars. The rotor lines of force,
moving in the same direction as those
of the stator, add to the magnetic field

TESDA-GOTEVOT
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Information Sheet 3

and the rotor keeps

Single Phase Motor 17

Many motor applications use
single phase power; especially for
smaller horsepower motors. Most of
these applications are residential and
light commercial, where three phase
power is generally unavailable. Single
phase AC motors differ from three
phase motors. In a three phase
motor, the incoming power produces
a rotating magnetic current on its
own. This allows the three phase
motor to be self starting. Single phase
motors require additional power in
order to produce a rotating magnetic
field. Once started, the motor has a
changing magnetic field at each pole,
allowing the motor to continue
running.

The most common method of
starting a single phase motor
combines a capacitor and auxiliary
winding or start circuit. A schematic
view shows an auxiliary starting
winding, a capacitor, and a centrifugal
switch. The auxiliary winding is
actually a second winding in the
motor.

When current is applied to the
motor, both the run winding and the
start winding produce magnetic fields.
Because the start winding has a
lower resistance, a stronger magnetic
field is created which causes the
motor to begin rotation. Once the
motor reaches about 80 percent of its
rated speed, a centrifugal switch
disconnects the start winding. From
this point on, the single phase motor
can maintain enough rotating

TESDA-GOTEVOT
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Information Sheet 3

magnetic field to operate on its own.
The graph shows a typical
torque/speed curve for auxiliary
starting on single phase motors.

There are a variety of starting
methods used in the different single
phase motor types. These are
covered in more detail in the
CONTROLS drawer under
"Starting." What these starting
methods all have in common is the
ability to produce a rotating magnetic
field using the input power that is
applied to the motor.

Three Phase Motors 18

Three phase AC power is
comprised of three independent
voltages. Each phase is displaced
120 degrees from the others.

When phase one (A) is at zero

TESDA-GOTEVOT
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Information Sheet 3

volts, phase two (B) is near its
maximum voltage and flowing in the
positive direction. The third phase (C)
is near its maximum voltage as well,
but flows in the negative direction.

These three phases will change from 19
positive to negative as the AC power
cycles. A rotating magnetic field is
produced if each of the three phases
is connected to an electrically
independent winding in an AC motor
stator.

In this example, using time 1 as our
reference point, the current flow in the
phase A winding is positive and pole
A1 is north. The opposite pole, A2 is
magnetically south. The resultant
magnetic field is shown moving from
north to south.

The current flow in the phase B
winding is negative, so pole B2 is
north and B1 is south. The resultant
magnetic field is shown flowing from
B2 to B1.

There is no current flow in red phase
C, so these poles are not
magnetized. They are neutral. The
result is that there is no magnetic field
being produced in this winding.

These magnetic fields produce a
rotating force in the direction shown
by the arrow. This arrow represents
the turning of the rotor.

TESDA-GOTEVOT
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Information Sheet 3

Moving to time 2, the red
phase C current is negative going,
thus poles C1 and C2 are south and
north respectively. Their blue phase B
current is positive going and poles B1
and B2 are north and south,
respectively. Because the green
Phase A is at zero, the A poles are
neutral. The arrow represents rotation
in the direction of the magnetic field.

Finally, at time 3, we see that
the green Phase A is positive going
and the red phase C is negative
going. Their respective poles are
energized with the resultant magnetic
fields producing a continuation of the
rotating magnetic field. This force is
what creates the motion of the rotor.

AC power cycles 60 times per
second between positive and
negative. In a fraction of a second,
the phases have shifted 60 degrees
causing the relationship of the north
and south poles to change at the
same rate. Because the motor has
established an induced magnetic
field, the opposite fields of the rotor
and stator attract each other, causing
the rotor to follow the stator's
magnetic field change.

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Information Sheet 4

Fan Motors

ELECTRIC FAN MOTOR

An electric fan motor is a mechanical device that converts electric energy into mechanical
motion. In an electric motor, electricity is used to produce magnetism. The magnetism is
used to turn a shaft, and the turning shaft is used to do work.

Electric motors are the most popular
and common type used for providing
mechanical power for air conditioning and
refrigeration system. They are popular
because they are readily available with the use
of electricity and their motors are simple.

MAJOR PARTS OF ELECTRIC (FAN)
MOTOR

1. Frame – the part that holds everything
together. It includes the end bell, outside
enclosure and the bearing or bushing.

2. Stator – the stationary part of the motor. It
includes the field coils (winding).

3. Rotor (armature) – the revolving part of the
motor. It includes the shafting.

In air conditioning unit fan motor is commonly used to drive the evaporator blower and
fan blade. The main purpose is to move the air across air-conditioning unit to create a free air
cycle. This will enable the fresh air to cool the condenser and at the same time circulate the
conditioned air around the conditioned room.

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Information Sheet 4

Fan motor used in air-conditioning units are capacitor motor with either a single or
multiple speed. The most commonly used is a two speed fan motor. The term speed here
refers to the rotation or revolution per minute of the fan motor.

1. Fan motor windings
A fan motor like the compressor, consist of magnet wire coiled in the slots at

the stator. This magnet wire converts the electricity into magnetic force which will
enable the rotor repulse into a rotating motion. The higher the magnetic force the
slower the rotor rotates.

The magnetic force of the fan motor winding depends on the amount of coil
resistance. The more coiled wires, the higher resistance it has and the greater
magnetic force it creates

You should understand that fan motor consist of two windings. These windings
are the main (running) winding and auxiliary (Starting winding. These two winding is
quite similar to compressor. As the name implies main winding sustain the operation
of the motor while auxiliary winding help the motor start.

There is only one feature which a fan motor plays advantage with compressor. A fan
motor is capable of increasing or decreasing the rotation speed. This is done by varying the
amount of magnetic force in a magnetic coil. Most fan motor employs two or three main
winding. This winding are called speed winding. The main winding is divided into segment,
namely, the first coil is the high speed winding, the high speed coil plus additional coil is
called the medium speed winding and the medium speed coil plus another coil is called the
low speed winding.

2. Fan motor Speed and Terminal Leads
Number of fan motor speed is easily identified by simply counting the numbers

of terminals. Most common as mentioned earlier is two speed fan motor. This kind of
motor usually has four (4) terminal leads, these are called as common, starting, fan
high and fan low. Likewise a three speed fan motor is composed of five (5) terminal
leads namely, common, starting fan high, fan medium and fan low.

The different types of fan motors are as follows
a. Three (3) leads single speed
This fan motor has three leads namely, common (represented by white
wire and connected to one line of the source), starting (represented by brown
wire and connected to the capacitor) and running (represented by black lead
connected to the switch).

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Information Sheet 4

Schematic symbol of a three leads single speed fan motor

b. Four (4) leads single speed (reversible)
This type of fan motor has the line lead (white wire), capacitor leads (two brown
wires) and running lead (black wire). There are two externally connected leads,
yellow and purple wires for changing the rotation of the fan motor.

c. Four (4) leads two (2) speed
Four leads fan motor has common lead (represented by white wire

connected to one line of the source), start lead (represented by red wire
connected to the capacitor) high speed lead (represented by black wire
connected to the switch) and low speed. Another wire codes used for this motor
is listed below:

Yellow wire = common lead

Blue wire = start lead

Red wire = low speed lead

Black wire = high speed lead

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Information Sheet 4

d. Five (5) leads three (3) speeds

Brown wire = Start lead

White wire = Common lead

Black wire = High speed lead

Blue wire = Medium speed lead

Red wire = Low speed lead

e. Six (6) leads three (3) speeds

Orange wire = Common or line lead
Brown wire = Start lead
Yellow wire = Common or fan capacitor
Red wire = Low speed lead
Blue wire = Medium speed lead
Black wire = High speed lead

Fan motor leads can also be identified using an ohm meter. Based on the
figure below you can see that the motor is composed of coils in series and parallel.

Auxiliary windings

The main winding and starting winding connected in series has the highest
resistance to the entire coil. The starting winding, auxiliary 1 and auxiliary 2 connected
in series has the second highest resistance. Auxiliary 1 and auxiliary 2 has the same
resistance. You can use this information to locate the different terminals of a five leads
2 speed motor (refer to operation sheet about identifying terminals of fan motor).

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Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
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Operation Sheet 3

Identify Fan Motor Terminals

Objectives: At the end of this activity, the learner/trainee should be able to:
o Identify fan motor terminals by color coding
o Identify fan motor terminals by using ohm meter
o Check the condition of fan motors

Materials, Tools and Equipment:

Materials:

o Fan motor - 1 pc

o Masking tape or other material which can

be used to tag the leads of fan motor

Equipment

o Ohm meter - 1 unit

* - Item is optional

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Operation Sheet 3

Introduction:

Terminal leads of fan motors are identified by color-coding and by the resistances of the
windings. The colors of the terminal leads may fade, making them hard to identify. The
terminal leads may have to be identified by the resistances of the windings.

Steps in identifying the terminal leads of a 3-speed fan motor
using an ohm meter

1. Label the terminal leads from 1 to 5 as shown in Figure 1. Use a masking tape.

Figure 1.

TERMINAL RESISTANCE RANK

S (OHMS)

1 1&2

2. Make a table like the one 2 1&3
shown on the right to record 3 1&4
the resistances of the 4 1&5
different terminal lead 5 2&3
combinations. 6 2&4

7 2&5

8 3&4

9 3&5

10 4 & 5

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Operation Sheet 3

3. Set the multimeter at R x 1. Measure and
record the resistances of the different
terminal lead. Use the table prepared in
Step 2.

NOTE:
Adjust first the VOM to zero reading before
taking any resistance reading.
Countercheck the values or resistances
(Figure 2).

Figure 2

4. Rank the readings from highest to lowest,
making the highest reading as rank 1 and
the lowest as rank. 10.

Figure 3 illustrates diagrammatically the windings of
a 3 -speed fan motor.

Figure 3: Windings of a 3-speed fan motor

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Operation Sheet 3

Characteristics of the Windings

Terminal:

A and C - highest resistance

A and L - second to the highest

H and M - is equal to M and L

C and H - higher than H and M or M and L

5. The terminal lead found both on the highest (Rank 1) and second highest resistance
(Rank 2) is the auxiliary terminal lead.

NOTE:

If there is no terminal lead found on both the highest and second highest resistance,
check the values by measuring the resistance of the terminal leads again.

a. With the auxiliary terminal lead now identified, the other terminal lead on the highest
reading (Rank I) is the COMMON terminal lead.

b. The other terminal lead on the second to the highest reading (Rank 2) is the LOW
terminal lead.

6. Using the LOW terminal lead now as the reference terminal, measure the resistance of
the two remaining terminal leads.

a. The one with the higher resistance is the HIGH terminal lead.

b. The other unidentified terminal is the MEDIUM terminal lead.

7. Using now the LOW terminal lead as the reference point, measure the resistance of the
other terminal leads.

NOTE:

If the terminal leads are identified correctly, they must follow the table below.

Terminals

L and A - highest resistance

L and C - second highest resistance

L and H - second lowest resistance

L and N - lowest resistance

TESDA-GOTEVOT 28
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Operation Sheet 3

NOTE:
If the readings of the resistances do not follow the pattern above, repeat identifying the
terminal leads.
Procedure:
Identifying terminals
1. The color coding of five leads 3 speed is written below.

Brown wire = Start lead
White wire = Common lead
Black wire = High speed lead
Blue wire = Medium speed lead
Red wire = Low speed lead

2. Given a five lead out fan motor, identify the terminals using the color coding system.

3. Using a masking tape tagged the leads with their corresponding terminals.

4. Upon completion, have it check by trainer.

TESDA-GOTEVOT 29
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Information Sheet 5

Compressor Motor Electrical Connection

There are four types of compressor connections used in air conditioning and
refrigeration units. The Permanent Split Capacitor (PSC) motor and Capacitor Start
Capacitor Run (CSIR) motor are use for air-conditioning units while Resistance Start-
Induction Run (RSIR) motor and Capacitor Start Induction Run (CSIR) motor are used for
refrigeration units.

The Permanent Split Capacitor (PSC) Motor
This compressor motor is ranging from ¾ hp to 2 hp. It employs running capacitor

connected in series with starting winding permanently. The capacitor remains in the circuit
while the motor is in operation. This enable to correct the power factor so that the line current
will be reduce and the motor operates in manner similar to two phase motor. This is a low
starting torque motor.

TESDA-GOTEVOT 30
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Information Sheet 5

Capacitor Start Capacitor Run (CSCR) Motor

CSCR motor employs two capacitors, one is running capacitor and the other one is
starting capacitor. These capacitors are connected in series with the starting winding. A relay
switch disconnects the starting capacitor while the run capacitor stays in the circuit as long
as the motor operates. This kind of motor is very efficient especially in high torque
application.

The operation and function is similar to PSC motor however, starting capacitor is
added to increase the starting torque. This capacitor provided with a switch that will cut off
the circuit once the compressor operates at a normal speed. Because of the efficiency in the
operation it is capable of starting even in an extreme load condition. This motor connection is
very popular in an air-conditioning with a compressor motor ranging from 2 hp to 7.5 hp.

TESDA-GOTEVOT 31
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Information Sheet 5

Resistance Start-Induction Run (RSIR) Motor

A resistance start induction run motor has an electrical winding on the motor for
starting purposes. This is commonly used in refrigerators ranging from 1/10 hp to 1/6 hp. A
special winding in the armature gives it high starting torque. The motor starts as a repulsion
motor, using brushes against a commutator in the armature winding circuit. This increases
the induced electrical flow in the armature and produces more magnetic power. As soon as it
reaches a certain speed, the armature winding are shorted. Then the brushes are usually
lifted from the commutator and the motor operates as induction motor.

TESDA-GOTEVOT 32
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Information Sheet 5

Capacitor Start Induction Run (CSIR) Motor

The operation of CSIR is quite simple, when the motor starts, the relay (closed when
the motor is running) causes the current to pass through both the starting and the running
winding. The starting winding is connected in series with the capacitor. This capacitor puts
the electrical surge in the starting winding out of step of phase with those of running winding.
At about 75% of motor’s rated speed, the relay opens and disconnects the starting winding.
The unit, however, continues to run as induction motor.

TESDA-GOTEVOT 33
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Information Sheet 5

Compressor Lock Rotor and Running Load Amperage (LRA and RLA)

All compressors has specific running load and lock rotor amperage. You should be
familiar with this current amperage rating because this is very critical especially in the field.
For your guide, the table below is very useful:

Motor Compressor Amperage Rating

Horse Power Lock Rotor Running Load
Rating Amperage Amperage
¾ 22.9
1.0 3.81 30.5
1.25 5.08 38.1
1.5 6.35 45.7
2.0 7.62 61.0
2.25 10.17 68.6
11.44

TESDA-GOTEVOT 34
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Self-Check 1

Compressor Electrical Connection

Test what you have learned about compressor electrical connection.

Fill in the Blanks
Direction: Complete the sentences below by filling the blanks with appropriate word/s.

1. The two types of compressor electrical connections in air conditioning units are
__________ and __________.

2. This kind of motor connection is usually used in air conditioning unit using a
compressor ranging from _________ and _________ horsepower.

3. Permanent split capacitor motor employs _________ capacitor connected in series
with the starting winding permanently.

4. Capacitor start capacitor run motor employs two capacitors, these are _________
and _________.

5. A _________ switch disconnects the starting capacitor connected while the run
capacitor stays in a circuit as long as the motor operates.

TESDA-GOTEVOT 35
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Answer Key 1

Compressor Electrical Connection

1. Permanent split capacitor motor and capacitor start capacitor run motor
2. ¾ to 2 hp
3. running
4. running capacitor and starting capacitor
5. relay

TESDA-GOTEVOT 36
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Operation Sheet 4

Objectives: Wiring of Permanent Split Capacitor Motor
Connection

At the end of this activity, the learner/trainee should be able to:
o Wire a permanent split capacitor motor
o Apply safety practices in wiring permanent split capacitor motor

Equipment: - 1 unit
o Multi meter - 1 unit
o Clamp Ammeter - 1 unit
o compressor
- 1 pc
Materials: - 1 roll
o rug - 1 pc
o masking tape - 1 pc
o overload protector - 10 pcs
o run capacitor - 1 pc
o terminal ends - 5m
o extension cord - 1 pc
o stranded wire, 12 AWG
o schematic diagram or working drawing - 1 pc
- 1 pc
Tools: - 1 pc
o Phillips screw driver
o Flat screw driver - 1 pc
o Long nose pliers
o Lineman’s Pliers - 1 pair
o Diagonal cutting pliers - 1 pc

Personal Protective Equipment:
o Gloves
o Goggles

TESDA-GOTEVOT 37
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Operation Sheet 4

Procedures:
1. Prepare the necessary tools,
equipment and materials.
Note: Always wear PPE as necessary!

2. Connect a compressor circuit using
Permanent Split Capacitor motor.
Refer to the diagram on the right.

3. Have your instructor check your work
before energizing.

4. Perform housekeeping.

TESDA-GOTEVOT 38
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Objectives: Operation Sheet 5

Wiring of Capacitor Start Capacitor Run Motor
Connection

At the end of this activity, the learner/trainee should be able to:
o Wire a capacitor start capacitor run motor
o Apply safety practices in wiring permanent split capacitor motor

Equipment: - 1 unit
o Multi meter - 1 unit
o Clamp Ammeter - 1 unit
o compressor
- 1 pc
Materials: - 1 roll
o rug - 1 pc
o masking tape - 1 pc
o overload protector
o run capacitor - 10 pcs
o starting capacitor - 1 pc
o terminal ends - 5m
o extension cord - 1 pc
o stranded wire, 12 AWG - 1 pc
o potential relay
o schematic diagram or working drawing - 1 pc
- 1 pc
Tools: - 1 pc
o Phillips screw driver
o Flat screw driver - 1 pc
o Long nose pliers
o Lineman’s Pliers - 1 pair
o Diagonal cutting pliers - 1 pc

Personal Protective Equipment:
o Gloves
o Goggles

TESDA-GOTEVOT 39
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Operation Sheet 5

Procedures:

1. Prepare the necessary tools,
equipment and materials.
Note: Always wear PPE as necessary!

2. Connect a compressor circuit using
CSCR. Refer to the schematic diagram
on the right.

3. Ask your instructor to check your work
before energizing.

4. Have your instructor check your work
before energizing.

5. Perform housekeeping.

TESDA-GOTEVOT 40
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Operation Sheet 6

Wiring of Capacitor Start Induction Run Motor
Connection

Objectives: At the end of this activity, the learner/trainee should be able to:
o Wire a capacitor start induction run motor
o Apply safety practices in wiring permanent split capacitor motor

Equipment: - 1 unit
o Multi meter - 1 unit
o Clamp Ammeter - 1 unit
o compressor
- 1 pc
Materials: - 1 roll
o rug - 1 pc
o masking tape
o overload protector - 10 pcs
o starting capacitor - 1 pc
o terminal ends - 5m
o extension cord - 1 pc
o stranded wire, 12 AWG - 1 pc
o potential relay
o schematic diagram or working drawing - 1 pc
- 1 pc
Tools: - 1 pc
o Phillips screw driver
o Flat screw driver - 1 pc
o Long nose pliers
o Lineman’s Pliers - 1 pair
o Diagonal cutting pliers - 1 pc

Personal Protective Equipment:
o Gloves
o Goggles

TESDA-GOTEVOT 41
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Operation Sheet 6

Procedures:
1. Prepare the necessary tools,
equipment and materials.
Note: Always wear PPE as necessary!

2. Connect a compressor circuit using
CSIR. Refer to the schematic diagram
on the right.

3. Ask your instructor to check your work
before energizing.

4. Have your instructor check your work
before energizing.

5. Perform housekeeping.

TESDA-GOTEVOT 42
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Information Sheet 6

Hermetic Motor Compressor

Hermetic motor is a very common and considered as an important component in
refrigeration system. The design characteristic of motor depends on whether the unit starts
under load, no load, or a balance pressure condition. The torque is provided by a magnetic
force developed in the field winding. They induce strong current to the rotor and in return it
drives the compressor crankshaft and the connecting rod to allow the piston to move up and
down. A compressor is either piston or roller type with the electric motor fastened in it. It is
sealed and the whole unit is house in a dome.

The higher the starting torque (turning effort) needed for that unit that starts under
load requires the use of larger conductors in the starting circuit. Most manufacturers try to
provide starting power equal to twice the running power. That is a 1/8 hp motor is designed
to produce ½ hp during starting.

Hermetic motors are either single phase or polyphase. In this segment only single
phase induction hermetic motors are explained. The figure below illustrates the construction
of hermetic motor.

TESDA-GOTEVOT 43
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Information Sheet 6

Compressor Winding

Hermetic compressor has its squirrel cage rotor directly coupled to the compressor
shaft and its stator inside the refrigeration system. The refrigerant vapor and oil surround the
whole unit. The construction and internal connection is similar to a split phase motor. It
consist of two identical windings the start and run winding. The former is fine while the latter
is a bigger wire wound in a core.

The split phase motors obtained the stator torque by adding a second winding to the
stator. This is a start winding. The conductor used in this winding is smaller than the
conductors used in run winding. It has higher resistance. Its purpose is to obtain a phase
displacement between windings so that it provides enough starting torque to spin the rotor.

Each winding has its specific resistance. The starting winding measures 30 ohms
while the run winding measures 4.5 ohms. These two windings are connected. The point of
connection is the common terminal. The end of starting is starting terminal while the other
end of running is running terminal. Since the windings are connected at common terminal.
The resistance is higher when measured between running and starting terminal which is 34.5
ohms. It is the combined resistance of two windings connected in series.

Hermetic Compressor Terminal

To obtain a correct compressor connection the motor terminal must be identified
correctly to prevent the motor from burning when supplied by electricity. Generally,
identification of compressor terminals is based on their arrangement. These are arranged in
triangular arrangements. The upper position is the “common” terminal; the left side is the
“starting” terminal and “running” on the other side. The figure below specifies the
arrangement of terminals.

COMMON

START RUN

Be careful not to interchange the connection to avoid burning out of windings. It will
immediately burn out after supplying power. The run winding should be wired directly to line
and should stay the circuit to maintain the rotor rotation while the start winding is wired to a
capacitor to correct the power factor of the compressor while it is operating.

If you are not certain, it is best to identify the terminal by testing the compressor
resistance. Just remember that the highest resistance is the combined resistance of starting
and running winding. The lowest resistance is the running winding while the joint wire of

TESDA-GOTEVOT 44
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Information Sheet 6

running and starting winding is the common terminal, the other end of each winding should
be running and starting winding terminal.

TESDA-GOTEVOT 45
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Self-Check 2

Hermetic Motor Compressor

Test what you have learned about hermetic compressor.

Fill in the Blanks
Direction: Complete the sentences below by filling the blanks with appropriate word/s.

1. Hermetic compressor is very common and considered as an important component
in _______________ system

2. A compressor is either __________ or __________ with electric motor fastened in
it.

3. It is sealed and the whole unit is housed in a __________.
4. Hermetic compressors are either _________ or _________.
5. The compressor winding is consist of two identical windings the _________ and

_________ winding.

TESDA-GOTEVOT 46
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0

Assignment Sheet 2

Identifying Hermetic Compressor Terminal

Objectives: At the end of this activity, the learner/trainee should be able to:
o Analyze the resistances of each terminal
o Identify the terminals.

Procedures:

1. The table shown below is an obtained test result of a 1.5 hp compressor, it reveals
that the resistances are;

Terminals Resistance
12 3.5 ohms
13 1.5 ohms
23 5 ohms

2. Identify among the three which is the common, start and run winding terminals
based on the given data in the table.

3. Upon completion, check your work with the answer key provided at the back of this
module.

TESDA-GOTEVOT 47
Troubleshooting Package Type Air Conditioning Unit and Commercial Refrigeration Equipment
Version 2007 -1.0