Troubleshooting Window-Type Air-conditioning / domestic refrigeration systems

Information Sheet3

Hermetic Compressor Motor Electrical Connection

There are four types of compressor motor 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.

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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 air-conditioning with a compressor motor ranging from 2 hp to 7.5 hp.

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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.

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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.

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

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Self-Check 3

Compressor Motor Electrical Connection

Test what you have learned about compressor motor 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.

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Compressor Motor 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

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Operation Sheet 2

Connecting Hermetic Compressor (Permanent Split
Capacitor Motor)

Objectives: At the end of this practice the learner/trainee will be able to:

o Connect PSC compressor motor
o Follow safety practices in connecting compressor motor.

Equipment: - 1 unit
o Multi meter - 1 unit
o Clamp Ammeter - 1 unit
o compressor
- 1 pc
Materials: - 1 roll
o rag - 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
- 1 pc
o schematic diagram or working drawing - 1 pc
- 1 pc
Tools:
o Phillips screw driver - 1 pc
o Flat screw driver
o Long nose pliers - 1 pair
o Lineman’s Pliers - 1 pc
o Diagonal cutting pliers

Personal Protective Equipment:
o Gloves
o Goggles

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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.

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Operation Sheet 3

Connecting Hermetic Compressor (Capacitor Start
Capacitor Run Motor)

Objectives: At the end of this practice the learner/trainee will be able to:

o Connect CSIR compressor motor.
o Follow safety practices in connecting compressor motor.

Equipment: - 1 unit
o Multi meter - 1 unit
o Clamp Ammeter - 1 unit
o compressor
- 1 pc
Materials: - 1 roll
o rag - 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 - 1 pc
o schematic diagram or working drawing - 1 pc
- 1 pc
Tools:
o Phillips screw driver - 1 pc
o Flat screw driver
o Long nose pliers - 1 pair
o Lineman’s Pliers - 1 pc
o Diagonal cutting pliers

Personal Protective Equipment:
o Gloves
o Goggles

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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.

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Operation Sheet 4

Connecting Hermetic Compressor (Capacitor Start
Induction Run Motor)

Objectives: At the end of this practice the learner/trainee will be able to:

o Connect CSIR compressor motor.
o Follow safety practices in connecting compressor motor.

Equipment: - 1 unit
o Multi meter - 1 unit
o Clamp Ammeter - 1 unit
o Compressor
- 1 pc
Materials: - 1 roll
o Rag - 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 - 1 pc
o schematic diagram or working drawing - 1 pc
- 1 pc
Tools:
o Phillips screw driver - 1 pc
o Flat screw driver
o Long nose pliers - 1 pair
o Lineman’s Pliers - 1 pc
o Diagonal cutting pliers

Personal Protective Equipment:
o Gloves
o Goggles

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

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

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

9. Have your instructor check your work
before energizing.

10. Perform housekeeping.

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Operation Sheet 5

Connecting Hermetic Compressor (Resistance Start
Induction Run Motor)

Objectives: At the end of this practice the learner/trainee will be able to:

o Connect RSIR compressor motor.
o Follow safety practices in connecting compressor motor.

Equipment: - 1 unit
o Multi meter - 1 unit
o Clamp Ammeter - 1 unit
o compressor
- 1 pc
Materials: - 1 roll
o rag - 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 - 1 pc
o schematic diagram or working drawing - 1 pc
- 1 pc
Tools:
o Phillips screw driver - 1 pc
o Flat screw driver
o Long nose pliers - 1 pair
o Lineman’s Pliers - 1 pc
o Diagonal cutting pliers

Personal Protective Equipment:
o Gloves
o Goggles

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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.

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Operation Sheet 6

Testing Compressor Motor Winding

Objectives: At the end of this practice the learner/trainee will be able to:

o Identify shorted compressor winding
o Identify open compressor winding
o Determine grounded compressor winding.
o Observe safety precautions in testing compressor winding.

Equipment: - 1 unit
o Multi meter 1 unit
o compressor
- 1 pc
Materials:
o rag - 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

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Procedures:
1. Unplug the unit

2. Disconnect the wiring connection of
compressor motor.

3. Set the multimeter to Rx1. Calibrate
the multimeter by adjusting the 0-ohm
adjust knob while the leads are
shorted.

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4. Record the resistance reading
obtained from the different terminals.

Using the formula:

SR = CR + CS

13Ω = 5Ω + 8Ω
13Ω = 13Ω, therefore compressor

motor winding is good.

Note: If the resistance reading did not
conform to the formula, compressor
motor winding is defective.

5. Set the ohmmeter to Rx10, 000.
Calibrate the meter to zero and place
the test prod to common terminal and
compressor body.

Note: If the pointer deflects, the
compressor is grounded. If the pointer
did not deflect, the compressor
winding is not grounded (good).

6. Observe the following data of winding
resistance to indicate possible
compressor troubles.

Troubles Test Point Meter Indicator
infinity
Open Winding Terminals 1 & 2 and 1 &3
(R x 1) Terminals 1 & 2 and 1 &3 0 ohm reading
With deflection or continuity
Shorted Winding Terminals to casing
(R x 1)

Grounded Winding
(R x 10k)

7. Have your instructor check your work.

8. Perform housekeeping.

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Job Sheet 2

Replace Compressor Motor

Objectives : When you have completed this job sheet, you will be able to:
 Replace defective compressor motor
 Follow safety practices in replacing defective compressor motor.

Equipment: - 1 unit
o Refrigerator Unit/Air-conditioning unit - 1 unit
o Set of system analyzer -
o Recovery/recycling machine -
o Torch set
- 1 pc
Materials: - 2 pcs
o Rag - 1 set
o Silver alloy brazing rod -
o Filter drier with sweat fittings -
o Sand cloth
o Silver brazing flux - 1 pc
- 1 pc
Tools: - 1 pc
o Tubing cutter - 1 set
o Striker - 1 pc
o Refrigeration ratchet wrench - 1 pc
o Combination open end, box end wrench
o Diagonal cutting pliers - 1 pair
o Shop towels - 1 pc
-
Personal Protective Equipment:
o Gloves
o Goggles
o Safety glasses

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1. Wear appropriate PPE

2. Check that the refrigerator is
disconnected from electrical power.
Caution: Make sure that the
unit has no pressure either
refrigerant or nitrogen.

3. Use sand cloth and polish the liquid
line prior to cutting

4. Disconnect electrical components
from the compressor.

5. Remove the compressor motor.

6. Install the new compressor.

Note: Make sure to clean the
system thoroughly before
connecting the new
compressor.

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7. Replace hold down bolts and tighten
to secure the new installed
compressor.

8. Reconnect the electrical connections
of the new compressor motor.

9. Ask your instructor to check your
work.

10. Perform housekeeping

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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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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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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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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

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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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Operation Sheet 7

Identify Fan Motor Terminals

Objectives: At the end of this practice, 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 - 1 unit
o Ohm meter

* - Item is optional

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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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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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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

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L and M - lowest resistance
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.

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Information Sheet 5

Identifying Capacitors

Capacitors

Capacitor is an electrical storage device used in starting and/or running circuitry in
many applications of electric motor. It is used for adding additional current to create a strong
starting torque and at the same time use to reduce line current and improve the power factor
of the motor.

There are two types of capacitor, namely start capacitor and run capacitor. The
function of start capacitor is to provide out of phase starting current to the starting winding,
forcing the motor to operate as two phase motor during starting period. It is designed to give
extra starting torque to provide the motor high starting capability.

Starting Capacitor

A starting capacitor is manufactured using a high purity aluminum foils, separated by
chemically treated pure paper saturated with electrolyte for low power factor. It is provided
with an internal protection against vibration and covered with seal made up of rubber
phenolic laminated and has a positive pressure safety vent. It is finish with high impact
phenolic case. Starting capacitor storage is normally in cylindrical form and with black color
casing.

Starting Capacitor Running Capacitor

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Run Capacitor

The primary function of running capacitor is used to reduce the line current while
greatly improving the torque characteristics of a motor. It reduces the line current of the
motor by improving the power factor of the load. It provides 90 electrical degrees phase
relationship between the capacitor current and voltage in conjunction with the motor windings
so that the motor will give two phase operation when connected to a single phase circuit.

The running capacitor is made up of finest dielectric paper and impregnated oil. It is
carefully process by vacuum heat treatment and then hermetically sealed in a sturdy metal
container, usually in oval form. This could be available either single or dual type.

Capacitor Replacement

The capacitor is rated in terms of ability to hold electric charge in micro farad (MFD or
µf). it is also specified in terms of maximum operating voltage. So when ordering capacitor
the MFD and the operating voltage should be carefully listed. For example 35 MFD/370 VAC
(Voltage Alternating Current). Several examples of capacitor applications are given in Table
1. These data are based on compressor manufacturer and are useful whenever you replace
capacitor.

HP Rating Staring Capacitor Run Capacitor
¼ MFD (µf)/VAC MFD (µf)/VAC

40/220

1/3 40-60/220

½ 40-60/220

3/8 40-60/220 8/440

¾ 40-60/220 10-15/440

1.0 60/220 15-20/440

1.25 80-120/220 20-25/440

1.5 80-120/220 25-30/440

2.0 80-120/220 30/440

2.25 80-120/220 35/440

NOTE: These data is based on Tecumseh compressor with
model series AE (1/4-3/4 hp), AJ (1.0-1.5 hp) and AH (2.0-2.25
hp).

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Replacement of defective capacitor should of course be made by using the identical
data. Not necessarily the same brand, but replacement which has the same capacitance
rating with the voltage equal to or higher than the failed unit.

Any deviation from the original capacitance value should be avoided as this will alter
the operating characteristics of the motor and may results in early failure.

When required capacitance value is not available it is possible in an emergency to
connect several capacitors in series or in parallel to obtain the desired capacitance. This
implies to both start and run capacitors to provide the desired characteristics if the voltage
and microfarads are properly selected.

Capacitor Connections and its Characteristics

When capacitors are wired in parallel connection, the capacitance rating increases.
This will add the capacitance value by summing up each rating. Example; a 15 MFD is
connected in parallel with 30 MFD, the total capacitance will be 45 MFD. It is express in
mathematical formula as

Total capacitance in parallel = µf1 + µf2

60µf = 15µf + 45µf

For total capacitance in series, the formula would be:

µft= µf1 x µf2
µf1 + µf2

For example, using the value of capacitor above if connected in series, the total
capacitance rating would be:

µft= 15µf x 45µf
15µf + 45µf

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Self-Check 4

Identifying Capacitors

Test what you have learned about capacitors.
ESSAY:

Direction: Answer the following briefly

1. What is capacitor?
2. Differentiate running capacitor and starting capacitor.
3. What are the types of compressor motor connection using starting capacitor?
4. What are the types of compressor motor connection using running capacitor?
5. What are the two type of capacitor connection?

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Identifying Capacitors

1. Capacitor is an electrical storage device used in starting and/or running circuit in
electric motors.

2. Starting capacitor is use in CSIR a CSCR compressor motor to give extra starting
torque for motor high starting capability while running capacitor is used in PSC and
CSCR for efficient compressor motor running operation. It also improves the torque
characteristics of a motor.

3. Running capacitor and starting capacitor
4. Types of compressor motor connection using starting capacitors are CSIR motor and

CSCR motor.
5. Types of compressor motor connection using running capacitors are PSC motor and

CSCR motor.
6. Type of capacitor connections are series connection and parallel connection.

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Operation Sheet 8

Testing capacitor using ohmmeter (Running and
Starting Capacitor)

Objectives: At the end of this practice the learner/trainee will be able to:

o Identify grounded, shorted, open and leaky capacitor.
o Discharge capacitor safely.
o Observe safety precautions in testing capacitor.

Equipment: - 1 unit
o Multi meter
- 1 pc
Materials: 1 pc
o Running capacitor
o Starting capacitor - 1 pc
1 pc
Tools: 1 pc
o Phillips screw driver 1 pc
o Flat screw driver 1 pc
o Lineman’s pliers
o Long nose pliers - 1 pair
o Diagonal cutting pliers - 1 pc

Personal Protective Equipment:
o Gloves
o Goggles

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Procedures:

1. Disconnect capacitor from the unit.

2. Discharge the capacitor by shorting the
terminals using a piece of wire.
Note: Capacitors must be
discharged before testing to
prevent damage to the meter.

3. Set the multimeter to Rx100 and
calibrate by adjusting the zero ohm
adjust knob

4. Connect the meter leads to the
capacitor terminals

Note: If the capacitor has
permanent bleed resistor
connected to the terminals,
disconnect at least one side of it.

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5. Observe the deflection of the meter
pointer.
Good – the pointer deflects to a
certain resistance and then slowly
return to infinity.

Shorted – the pointer deflects to
zero and stays there.

Open – no deflection at all.

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Leaky – the pointer deflects to zero,
return to a definite resistance and
stays there.

6. If the capacitor is defective, mark it
using permanent marker or a piece of
masking tape.

7. Have your instructor check your work.
8. Perform housekeeping.

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Job Sheet 3

Replace Capacitors

Objectives : When you have completed this job sheet, you will be able to:
 Replace defective capacitor
 Follow safety practices in replacing defective capacitor

Equipment: - 1 unit
o Multi meter - 1 unit
o Domestic Refrigeration/Air conditioning
- 1 pc
Unit - 1 pc
- 1 pc
Materials:
o Rag - 1 pc
o Wires - 1 pc
o terminal lugs - 1 pc
- 1 pc
Tools: - 1 pc
o Phillips screw driver
o Flat screw driver - 1 pair
o Long nose pliers - 1 pc
o Diagonal cutting pliers - 1 pair
o Lineman’s pliers

Personal Protective Equipment:
o Gloves
o Goggles
o Safety shoes

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Procedures:
1. Wear appropriate PPE

2. Disconnect power cord to electrical
power

3. Pull-out air-conditioning
unit/refrigerator

4. Disconnect capacitor’s electrical
connections and remove the defective
capacitor.

5. Install the new capacitor

6. Reconnect capacitor’s electrical
connections

Note: To tighten the terminal
lugs, press it with pliers at its side.

7. Have your instructor check your work

8. Connect the unit to electrical power

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9. Place the ammeter probe to one line
of the power cord and check the
running amperage

10. Have the instructor check your work
11. Disconnect the unit from electrical

power
12. Reinstall the unit.
13. Perform housekeeping.

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Information Sheet 6

Selector Switch

Selector switch is an electrical device fitted to the air-conditioning unit for switching
operation. It is capable of changing the air-conditioning operating function from a low cool to
fast cool.

A selector switch is either a push button switch, rotary shifting switch or electronic
selector switch. It is a combination of mechanical or electrical contacts that allows
compressor and fan motor to operate by connecting it to the source line.

The selector switch generally has three switching position namely, fan, low cool,
medium cool and high cool. It is capable of switching compressor and fan motor
simultaneously. It changes the fan motor operation without affecting the compressor. Below
is a chart which describes the operation of a selector switch:

Switch Position Compressor High Terminal Fan Motor Low Terminal
Motor 0 Med Terminal 0
Off 0 0 0
Fan 0 0 0 1
Low cool 1 0 1 0
Medium cool 1 1 0 0
High cool 1 1
Legend: 0

0 – OFF
1 - ON

As you can see, the compressor only turns ON at low cool, medium cool and high cool
settings while the fan motor turns ON at all setting except OFF. It only varies its speed in
accordance with the selector setting.

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Operation Sheet 9

Checking Selector Switch

Objectives: At the end of this practice the learner/trainee will be able to:
o Locate the terminal for common, compressor and fan speeds

terminals in the selector switch
o Check the condition of the selector switch

Materials Tools and Equipment:

Materials - 1 unit
o Selector switch (push button)

Equipment
o Multitester

* - Item is optional

Introduction:
Selector switch is a mechanical control intended to turn on the fan and compressor of

the air-conditioning unit. It is also the control for the different fan speed like low, medium and
high cool.

Defective switch may be mistaken as defective fan motor or defective compressor if
not checked properly. Below is the procedure in testing selector switch.

Procedure:

Table 1

1. Analyze table 1. You will use this as Switch Compressor Fan Motor
reference in checking the selector Position Motor High Med Low
switch. Terminal Terminal Terminal

Off 0 0 0 0

Fan 0 0 1 0

Low 1 001
cool

Medium 1 010
cool

High 1 100
cool

Common terminal is used as reference for this table.

Legend:
0 – Open contact
1 – Closed contact

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2. Locate the common terminal of the L1 label
selector switch. Usually the common
terminal of the selector switch has the
label L1. If the label has been erased,
you can locate it by using an ohm
meter or continuity tester.

The common terminal will be the
source line of compressor motor and
fan motor therefore it has a contact on
the compressor terminal, low cool
terminal when the selector is switched
to low cool mode; it has a contact on
the compressor and medium terminal
when the selector is switched to
medium cool mode; or it has a contact
on or high cool terminal every time the
switches are activated (see table 1 for
more information).

3. Switch the selector to OFF mode. Then
measure the continuity of the terminals
L1 - PL, L1 - 1, L1 - 4, L1 - 3 and L1 - 2.
Based from the chart on step 1, there is
no closed contact on any of the
terminals in reference with common
terminal when the selector is switched
to OFF mode.

4. Turn the selector switch to fan mode. Terminals Table 2
Measure the continuity of all terminals Is there a
in reference with the common terminal. L1-PL
Answer the table. L1-1 connection?
L1-4 Yes No
L1-3
L1-2

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5. Turn the selector switch to low cool Terminals Table 3
mode. Measure the continuity of all Is there a
terminals in reference with the common L1-PL
terminal. Answer the table. L1-1 connection?
L1-4 Yes No
6. Turn the selector switch to medium cool L1-3
mode. Measure the continuity of all L1-2 Table 4
terminals in reference with the common Is there a
terminal. Answer the table. Terminals
connection?
7. Turn the selector switch to high cool L1-PL Yes No
mode. Measure the continuity of all L1-1
terminals in reference with the common L1-4 Table 5
terminal. Answer the table. L1-3 Is there a
L1-2
Based on table 1. Analyze the result of connection?
your measurement (see table 2-6) Terminals Yes No

The common terminal is the terminal L1-PL
which have continues connection when the L1-1
selector is switched to low cool, medium L1-4
cool and high cool. L1-3
L1-2
Low cool terminal is the terminal with
connection every time the selector is
switched to low cool.

Medium cool is the terminal with
connection every time the selector is
switched to medium cool.

High cool is the terminal with
connection every time the selector is
switched to high cool.

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Information Sheet 7

Electrical Controls: Current and Potential Relays

1. As the motor runs, the control bulb is Relay – current type
cooled and the pressure in the bellows
is reduced. The reduction of pressure
allows the spring to push the bimetal in
opposite directions, snapping the switch
and stopping the motor. The control
bulb slowly warms up until the motor
starts again and the cycle is repeated.

Current relays and magnetic switches
are generally used on low torque
smaller (H.P.) motors. Shown below is
the diagram of a current relay switch.

Shown below is a diagram of current relay and magnetic switch connection.

Current Relay Connection

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1. Current relay and magnetic switch are
normally open, as shown.

2. This normally open contact closes
immediately when the motor is energized
by the surge of current which occurs at the
time of starting (see illustration at right).

3. When the motor speeds up, the current drops and the magnetic coil which is in the main
winding circuit releases the movable contact, disconnecting the starting winding, as
shown.

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4. POTENTIAL RELAYS are generally used on high torque capacitor motors. Shown below
is diagram of the parts of a potential relay.

Parts of Potential Relay
POTENTIAL RELAY CONNECTIONS
High starting torque motors 2 terminal overload potential relay

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