Troubleshooting Window-Type Air-conditioning / domestic refrigeration systems

1. The contacts are normally closed, as
shown.

2. The coil is continuously connected to the
starting winding, as shown.

3. The coil opens the starting contact when a
predetermined voltage appears across it,
as shown.

4. The contacts remain open during normal
operation, due to the induced start winding
voltage, as shown.

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5. Contact closes when the voltage across it
is cut or stopped.

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Self-Check 5

Electrical Controls: Current and Potential Relays

Direction: Read the items carefully and answer each question correctly. Write only the letters
on the space provided.

_____ 1. The function of which is to disconnect the motor from the source when the motor
becomes overloaded
a. pressure control
b. thermostat
c. temperature control
d. overload protector

_____ 2. Which one is NOT an electric control?
a. float switches
b. relays
c. capacitor
d. thermostat

_____ 3. An automatic switching device that disconnects the starting winding after reaching
its three-fourth rated speed is called
a. relay
b. overload
c. thermostat
d. running capacitor

_____ 4. A relay generally used on low torque smaller H.P. motor.
a. potential
b. current
c. pilot
d. capacitor

_____ 5. A winding of the motor that is disconnected when the motor has reached its
equivalent value
a. running
b. common
c. starting
d. secondary

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_____ 6. Current and potential relays have similarities except in
a. overload
b. compressor terminals
c. control
d. motor capacity

_____ 7. When the motor resumes its normal operation, this winding is the only one
connected to the circuit.
a. starting
b. running
c. secondary
d. common

_____ 8. A type of relay generally used on a high torque capacitor motor.
a. potential
b. current
c. pilot
d. hot wire

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Electrical Controls: Current and Potential Relays

1. d
2. c
3. a
4. b
5. c
6. d
7. b
8. a

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Operation Sheet 10

Checking Current Relay (Coil type)

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

o Identify defective relay contacts.
o Follow steps in checking current relays.

Equipment: - 1 unit
o Multi meter - 1 unit
o Refrigeration Unit
- 1 pc
Materials:
o Current relay, coil type - 1 pc
1 pc
Tools:
o Phillips screw driver - 1 pc
o Flat screw driver - 1 pc
o Lineman’s pliers - 1 pc
o Long nose pliers - 1 unit
o Diagonal cutting pliers
o Multimeter - 1 pair
- 1 pc
Personal Protective Equipment:
o Gloves
o Goggles

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Procedures:

1. Unplug the unit.

2. Disconnect wiring connection of
current relay and remove it to from the
compressor.

3. Set the multimeter to Rx100 and
calibrate the meter through zero ohm
adjust knob.

4. Place the test prods of the meter to L
and M terminals of the current relay.

5. Hold the current relay in upside down
position.

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6. Observe the deflection of the meter
pointer.

Note: If the ohmmeter reads
approximately 1 ohm, the relay is
good, if the pointer did not deflect,
the current relay is open.

7. Now place the test prods of the meter
to L and S terminals of the current
relay while the relay is in upside down
position

Note: If the pointer did not deflect,
the relay contact is open as it
should be, but if it has low
resistance reading, the contacts are
stuck-up and therefore defective.

8. Transfer the test prods on M and S
terminal. Still in upside down position.
Note: If the ohmmeter reads a low
resistance, the contacts are close
(good), but if the pointer did not
deflect, contacts are not closing
properly.

9. Have your instructor check your work.

10. Perform housekeeping.

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Operation Sheet 11

Checking Potential Relay (Voltage Relay)

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

o Identify defective potential relay using multimeter
o Follow steps in checking potential relay.

Equipment: - 1 unit
o Multi meter - 1 unit
o Refrigeration Unit
- 1 pc
Materials:
o Potential Relay - 1 pc
1 pc
Tools:
o Phillips screw driver - 1 pc
o Flat screw driver - 1 pc
o Lineman’s pliers - 1 pc
o Long nose pliers
o Diagonal cutting pliers - 1 pair
- 1 pc
Personal Protective Equipment:
o Gloves
o Goggles

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Procedures:

1. Unplug the unit.

2. Disconnect wiring connection from potential
relay and remove it from the compressor.

3. Set the multimeter to Rx100 and calibrate
the meter through zero ohm adjust knob.

4. Place the test prods of the meter to #5 and
#2 terminals of the potential relay.

5. Observe the deflection of the meter pointer.
Note: If the ohmmeter reads a resistance,
the relay coil is good. If the pointer did
not deflect, the coil is open.

6. Now place the test prods of the meter to #1
and #2 terminals of the potential relay.
Note: If the ohmmeter reads a low
resistance, the contacts are close (good),
but if the pointer did not deflect, contacts
are open and it is defective.

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

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Information Sheet 8

Overload Protector

INTRODUCTION

Overload protector is in series with the running and starting winding. Overload protector
allows an excessive current for a very short time (about 3 to 4 seconds - approximate time
for the motor to start. It will break the circuit of the high current flows lasts for any length of
time (5 seconds or more) As shown in figure below.

Wiring Diagram
A. External Overload Protector

An overload protector during normal and
overcurrent/over heating conditions.

When there is a high rise in temperature, Normal condition (contact close)
copper expands more than steel, causing
warping (or bending) of the bimetal disc Over control/overheating
which opens the overload contacts thus, (contacts open)
removing the motor from the circuit. When
the temperature goes down to normal Overload protector on normal and
level, the bimetal disc returns to its normal overheating or overheating position.
position and the contact points close.

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Basic Parts of an Overload Protector

1. Heater - safeguards the
compressor against the overcurrent.
It is in series with the contacts and
the motor windings. When the motor
is subjected to a sustained
overcurrent, the current through the
heater is high, and the temperature
of the heater increases. This heats
the bimetal disc.

Parts of an overload protector.

2. Bimetal disc and contacts

Safeguards the compressor motor Overload Protection
against overheating. The bimetal is
positioned beside the heater and this
senses the temperature change in the
heater and compressor dome (or
housing). It opens or closes the
contacts depending on the
temperature condition of the motor.

3. Terminals and pin connector
- enable the overload protector to

be electrically connected to the circuit.

4. Case - holds the other parts in place.
Also makes the installation of the
overload protector possible.

B. Internal Overload Protector

Internal overload protector is mainly used
in hermetic motors. It is installed inside the
motor winding and protects the motor from
overheating. When the winding
temperature rises above safe limits, the
internal overload protector opens and
disconnects the motor windings from the
power source, preventing damage to the
motor.

Locations of internal overload protector

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Internal overload protector

The contact points are made of fine silver for excellent conduction of current. The bimetal
strip (disc) responds to temperature in the motor windings and closes the circuit when the
temperature goes down to a safe value.

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Self-Check 6

Overload Protectors

A. Without looking back on the previous pages, answer the following questions on a piece of
paper:

1. What are the functions of an overload protector?

2. How does a bimetal disc open or close the circuit?

3. What is the purpose of the heater?

4. Differentiate an external overload protector from an internal overload protector

B. Below are the parts and an illustration of an overload protector. Identify the parts by writing
the corresponding number of each part in the circle provided in the illustration. When you
have completed the activity. CALL YOUR INSTRUCTOR.

Parts of an Overload Protector

_______________ Case _______________ Bimetal disc
_______________ Terminals _______________ Contact
_______________ Pin Connector _______________ Heater

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Operation Sheet 12

Checking Overload Protector

Objectives: At the end of this practice the learner/trainee will be able to:
o Identify defective overload protector.

Equipment: - 1 unit
o Multi meter - 1 unit
o Refrigeration Unit
- 1 pc
Materials:
o Overload protector - 1 pc
1 pc
Tools:
o Phillips screw driver - 1 pc
o Flat screw driver - 1 pc
o Lineman’s pliers - 1 pc
o Long nose pliers
o Diagonal cutting pliers - 1 pair
- 1 pc
Personal Protective Equipment:
o Gloves
o Goggles

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Procedures:
1. Unplug the unit.

2. Disconnect wiring connection from
overload protector and remove it from
the compressor.

3. Set the multimeter to Rx1 and calibrate
the meter through zero ohm adjust
knob.

4. Place the test prods of the meter to 1
and 3 terminals of the OLP

5. Observe the deflection of the meter
pointer.
Note: Good – if it indicates low
resistance reading; Defective – no
deflection.

6. Have your instructor check your work.

7. Perform housekeeping.

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Information Sheet 9

Temperature Control Switch (Thermostat)

INTRODUCTION
Most refrigerator manufacturers design their units to operate only for 8 to 14 hours a

day. This is done by means of a thermostat temperature actuated control.
FOUR TYPES OF SENSING ELEMENTS OR BULBS USED IN A THERMOSTAT
1. Sensing element with gas charged

temperature bellows.
2. Vapor pressure temperature bellows.

3. Liquid charged temperature response
diaphragm.

4. Capillary tube coil used as bulb.

5. The capillary tube is the one that contacts the sensing element and the operating
mechanism.

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6. Copper has a greater coefficient of expansion than iron. This bimetal strip will bend as
the temperature changes. The bending action of the bimetal will open and close the
contact point in an electrical circuit. You will observe that when the bimetal is heated, it
bends upward and when cooled, it bends downward.

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FUNCTIONS OF A THERMOSTAT
1. It starts the compressor driving motor.

2. It stops the compressor driving motor.

PRINCIPLES OF OPERATION
1. Any change in temperature will be sensed

by the sensing bulb.

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2. The bellows will expand or contract
3. The bellows will push the bimetal.
4. The contact will be closed.

5. When contact is made, the motor
compressor will run until such time that the
predetermined cooling temperature is
attained.

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6. When the predetermined temperature is
attained, the sensing bulb senses the
temperature, the bellows contract, contact
is cut off and the compressor motor stops.

RANGE ADJUSTMENT

It is the difference between the cut-in and
cut-out temperatures.

Example: cut-in temp. = 30F
cut-out temp. 20F

The range is between 30F and 20F
limits.

DIFFERENTIAL ADJUSTMENT

It is the difference in cut-in and cut-out
temperatures.

Example: cut-in temp. = 30F
cut-out temp. = 20F
differential = 10F

METHODS OF ADJUSTING THE RANGE SETTING

1. Turning the range adjusting screw
clockwise increases the spring tension and
raises the cut-in and cut-out temperatures.

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2. Turning the range adjusting screw
counterclockwise decreases the spring
tension and lowers the cut-in and cut-out
temperatures.

METHODS OF ADJUSTING THE DIFFERENTIAL ADJUSTMENT

1. Turning the differential adjusting screw
clockwise causes the limit bar to move
towards the screw head, thereby
increasing the travel of pin B in the slot.
This increases the differential by lowering
the cut-out temperature.

2. Turning the differential adjusting screw
counter clockwise raises the cut-out
temperature and reduces the differential.

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Self-Check 7

Temperature Control Switch (Thermostat)

MATCHING TYPE:

Direction: Matching type. Match column A with column B by writing the answer on the space
provided.

Column A Column B
______ 1. Sensing bulb
a. part of a thermostat that gets in contact
with metal during an increase in
temperature

______ 2. Bellows b. part of thermostat that relays the
temperature to the bellows

______ 3. Bimetal c. it connects the sensing bulb and the
bellows.

______ 4. Copper d. a metal which has a greater coefficient
of expansion than iron

______ 5. Contact point e. the point where the flow is opened or
closed

______ 6. Evaporator f. part of the system where the sensing
bulb is mounted firmly

______ 7. Range adjustment g. the difference between cut-out and cut-
in temperature

______ 8. Differential adjustment h. change within limit

i. snap action

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Temperature Control Switch (Thermostat)

1. b
2. a
3. c
4. d
5. e
6. f
7. i
8. g

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Operation Sheet 13

Checking Thermostat

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

o Identify defective thermostat
o Follow safety practices in checking thermostat.

Equipment: - 1 unit
o Multi meter - 1 unit
o Refrigeration/Air conditioning Unit
- 1 pc
Tools: 1 pc
o Phillips screw driver
o Flat screw driver - 1 pc
o Lineman’s pliers - 1 pc
o Long nose pliers - 1 pc
o Diagonal cutting pliers
- 1 pair
Personal Protective Equipment: - 1 pc
o Gloves
o Goggles

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Procedures:
1. Unplug the unit.

2. Disconnect wiring connection of the
thermostat and remove the thermostat
from the unit.

3. Set the multimeter to Rx1 and calibrate
the meter through zero ohm adjust
knob.

4. Place test probes across terminals of
thermostat
Note: The cord is good if there is
continuity. It is defective if the
pointer did not deflect.

5. Observe the meter reading;

Good: At OFF position there must
be no continuity between terminals.
At ON position, there must be
continuity between terminals.

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Defective: At ON position, no
continuity. At OFF position, there is
continuity between terminals.

6. Check the refrigerant charge at the
capillary tube. To do this, prepare
water with ice in a small container.
Note: The container must be big
enough for the thermocouple to
submerge.

7. Turn the thermostat ON. Place the test
probes across the terminals of the
thermostat.
Note: There must be continuity
between terminals.

8. Submerge the thermocouple in the
container with water and ice. Wait for a
few moments.
Note: The thermostat must turn
OFF after few moments. If the
thermostat did not turn OFF, it is
defective.

9. Have your instructor check your work.

10. Perform housekeeping.

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Information Sheet 10

Defrost Timers

TECHNICAL INFORMATION:

The most common method of defrosting a refrigerating system is to turn the
system “OFF” until all the frost in the evaporator/freezer melts, after which it is turned
“ON” again manually.

In systems where automatic defrosting is required, a defrost timer is used to shut
the system down, and to start it again when the unit is defrosted. These timers defrost
the refrigerating system for a fixed period of time at regular intervals of 12 or 24 hours,
depending on the specific requirements of the unit.

Figure 1 shows a typical diagram of the electrical circuit used in an automatic defrost
refrigerator. During the defrosting process, the compressor is turned off and current flows
into the defrost heater which melts the frost.

Figures 2-A and 2-B show the commonly used defrost timers in refrigerators. Figure 2-C
illustrates the switching mechanism of a typical defrost timer. Defrost timers consists simply
of a synchronous motor driving a single-pole-double-throw switch (SPDT). The motor makes
one defrost cycle every 12 hours.

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Figure 2-A. Parts of a defrost timer.

Figure 2-C. Symbol of the defrost timer shown in
Figures 2-A & 2-B.

Figure 2-B. Another form of defrost timer.

HOW THE DEFROST TIMER OPERATES

During the refrigeration cycle, the defrost timer switches the compressor ON and the
defrost heater is turned off (Figure 3). After a specific length of time, the defrost heater is
switched ON automatically, (see Figure 4). The defrost heater, which is attached to the
evaporators then melts all the frost. The timer stays in the defrost position from 12 to 30
minutes depending on the manufacturer’s specifications. After all the frost is melted, the
defrost heater is turned OFF and the compressor is again switched on.

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Figure 3. Defrost timer in refrigeration position. Figure 4. Defrost timer in defrost position.

Another type of defrost timer is shown in Figure 5. The additional switch makes it possible
for the connection of other electrical components to be controlled by the defrost timer.

Figure 5. Defrost timer with switches.

EVAPORATOR FAN CONTROLLED BY THE DEFROST TIMER

Figure 6 illustrates the wiring diagram of a refrigerator using an evaporator fan. As shown,
the fan is controlled by the defrost timer. When the timer is in defrost mode, the compressor
and the evaporator fan are removed from the circuit. The defrost heater melts all the frost,
after which the compressor is in operation for 5 minutes. The fan is not activated immediately
so that it will not circulate the hot air generated by the defrost heater (see Figure 7-9 for
details).

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Figure 6. Electrical circuit for delayed fan shut off during defrost.

Figure 7. Defrost timer in refrigeration position. Figure 8. Defrost timer at start of defrost cycle.

Figure 9. Defrost timer near end of defrost cycle.

Figure 10. Defrost timer which only shuts off the
refrigerating unit. No defrost heater used. (Timer

on defrost position)

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The same defrost timer can be used for several types of defrost control arrangements.
Figures 10 - 13 illustrate these variations as used by different manufacturers of automatic
defrost refrigerators.

Figure 11. Defrost timer which turns on defrost Figure 12. Defrost timer which shuts off
heater as it shuts off the refrigerating unit. (Timer compressor and fan motor and turns on the defrost
on defrost position)
heater. (Timer on defrost position)

In some refrigerators, the defrost timer
turns on a solenoid valve instead of a defrost
heater.

Figure 13. Defrost timer which shuts off the
compressor and fan motor and turns on two
defrost heaters. (Timer on defrost position)

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Self-Check 8

Defrost Timers

Without looking back at the previous pages, answer the following questions briefly.

1. What is the use of the defrost timer?

2. Sketch the electrical diagram of a defrost timer controlling the compressor and a
defrost heater.

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Information Sheet 11

Operation of a Semi-Automatic Defrost Timer

Too much time and effort are usually spent manually in defrosting a refrigerator. To
defrost the refrigerator it is turned off and is turned on again when all the frost have melted
and removed from the evaporator.

However, semi-automatic defrost refrigerators are defrosted by manually starting the
defrost unit but will automatically run normally when all the frost have melted.

Figure 1 shows the wiring
diagram of a semi-automatic
defrost refrigerator. It has two
controls: the thermostat and the
defrost control.

- The thermostat controls
the operation of the
compressor motor.

- The defrost control
operates the solenoid
valve.

Figure 1. Wiring diagram of a semi-automatic defrost refrigerator.

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During normal operation, no current flows to the
solenoid valve so the valve is closed. Figure 2 shows a
refrigeration cycle. The refrigerant flows to the
condenser, to the capillary tube, and then, to the
evaporator where it does some cooling.

During the defrosting period, the compressor
runs continuously.

Figure 2. Refrigerating in refrigeration
cycle (Solenoid valve is close)

To defrost the system, the defrost control
button is pressed. Current flows to the
solenoid valve so that the valve opens. Figure
3 shows the system in defrost position. The
refrigerant from the compressor now flows
directly to the evaporator. The hot refrigerant
from the compressor melts the frost on the
evaporator.

When all the frost are melted, the defrost
control automatically turns off the solenoid
valve. The refrigerant flows to the condenser.
The system is now in normal operation.

Figure 3. Refrigeration system in defrost
position (Refrigerant flows through the

tube with less resistance))

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Figure 4 shows a thermostat and a defrost
control combined. The thermostat has its own
sensing bulb to control the compressor motor.
The defrost control also has its own sensing
bulb to control the solenoid valve. The sensing
bulb of the defrost control detects the
presence or absence of frost in the evaporator.

When the sensing bulb has detected that all
the frost are melted during the defrosting
period, it cuts the flow of current to the
solenoid valve.

Figure 4. When frost accumulates in the
evaporator again, press the push button to
defrost it. When all the frost are melted, the

refrigerator automatically operates
normally all over again.

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Self-Check 9

Operation of a Semi-Automatic Defrost Timer

Without looking back at the previous pages, answer the following questions. Write the
letter only of the correct answer in a separate answer sheet.

1. To defrost a semi-automatic defrost refrigerator, one must:
a. turn off the thermostat
b. press the defrost button
c. remove/unplug the unit
d. leave the door open

2. The defrost control operates the:
a. cabinet light
b. compressor motor
c. solenoid valve
d. starting relay

3. During the defrosting period, the solenoid valves are
a. opened
b. closed
c. turned on
d. turned off

4. Circuit Diagram

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Operation Sheet 14

Testing Defrost Timer

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

o Identify defective defrost timer.
o Follow steps in testing defrost timer.

Equipment: - 1 unit
o Multi meter - 1 unit
o Refrigeration Unit
- 1 pc
Tools: 1 pc
o Phillips screw driver
o Flat screw driver - 1 pc
o Lineman’s pliers - 1 pc
o Long nose pliers - 1 pc
o Diagonal cutting pliers
- 1 pair
Personal Protective Equipment: - 1 pc
o Gloves
o Goggles

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Procedures:

1. Unplug the unit.

2. Disconnect all wiring connection from
the selector switch.

3. Set the multimeter to Rx1 and calibrate
the meter through zero ohm adjust
knob.

4. Place the test probes to terminal pin 1
and 3. This is the motor coil.

5. Observe the meter reading;

Good: If 1 and 3 terminals indicate
resistance reading, the motor coil is
intact.

Defective: Infinite reading

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6. Test the contacts. Place the test
probes to terminal pin 1 and 4. There
must be continuity.

7. Turn the defrost timer knob counter
clockwise until clicking sound is heard.

8. The contacts 1 and 4 must be open at
this moment, contact between 1 and 2
will close. If this scenario did not
happen, the defrost timer is defective.

9. Have your instructor check your work.
10. Perform housekeeping

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Job Sheet 4

Replace Defrost Timer

Objectives : When you have completed this job sheet, you will be able to:
 Replace a defective defrost timer
 Follow safety practices in replacing defective components.

Equipment: - 1 unit
o Multi meter - 1 unit
o Refrigerator unit
- 1 pc
Materials:
o Rag - 1 pc
- 1 pc
Tools: - 1 pc
o Phillips screw driver - 1 pc
o Flat screw driver
o Long nose pliers - 1 pair
o Diagonal cutting pliers - 1 pc
- 1 pair
Personal Protective Equipment:
o Gloves
o Goggles
o Safety shoes

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Procedures:
1. Wear PPE

2. Disconnect electrical power to the
refrigerator.

3. Locate defrost timer at the back of
the unit.

4. Remove mounting screws to loosen
the timer.

5. Pull timer out enough to disconnect
the wires.

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6. Disconnect wires from the timer.
Note: If necessary mark all

terminals by taping it with masking
tape before removing the wires.

7. Reconnect electrical wires and install
the new defrost timer.

8. Have your instructor check your
work.

9. Plug in refrigerator to electrical power
and check the amperage.

10. Have your instructor check your
work.

11. Perform housekeeping.

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Operation Sheet 15

Test Air Swing Motor

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

o Identify defective air swing motor
o Follow steps in testing air swing motor.

Equipment: - 1 unit
o Multi meter - 1 unit
o Air conditioning unit
-
Materials: - 1 pc
o Rag - 1 pc
o Sand paper - 1 pc
o Pencil/ballpen
o Air swing motor - 1 pc
- 1 pc
Tools: - 1 pc
o Philips screw driver - 1 pc
o Flat screw driver - 1 pc
o Long nose pliers
o Diagonal cutting pliers - 1 pc
o Line man’s pliers - 1 pair
- 1 pair
PPE:
o Goggles
o Gloves
o Safety shoes

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Procedures:
1. Wear PPE
2. Unplug the unit

3. Disconnect wire terminals of air swing
motor from the unit.

4. Set the multimeter to Rx1 and calibrate
the zero ohm adjust knob to ensure
accurate reading.

5. Test the resistance of the coil of air
swing motor.

Note: Good – has a resistance
reading; open – infinite; shorted –
zero ohm reading. Grounded if the
pointer deflects from one terminal
against the metal casing of the air
swing motor.

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

Code No. Troubleshooting Window Type Air- Date: Developed Date: Revised Page #

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Job Sheet 5

Replace Air Swing Motor

Objectives : When you have completed this job sheet, you will be able to:
 Replace defective air swing motor
 Follow steps in replacing defective air swing motor.

Equipment: - 1 unit
o Multi meter - 1 unit
o Window Air Conditioning Unit
- 1 pc
Materials: - 1 pc
o Rag - 1 pc
o sand paper 1 unit
o pencil/ball pen
o Air swing motor - 1 pc
- 1 pc
Tools: - 1 pc
o Phillips screw driver - 1 pc
o Flat screw driver
o Long nose pliers - 1 pair
o Diagonal cutting pliers - 1 pc
o Lineman’s pliers - 1 pair

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. Remove the defective air swing motor

4. Install the new air swing motor to its
location

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5. Reconnect the wire of the air swing
motor to the terminal marked for the
terminal

6. Have the instructor check your work
7. Connect the unit to electrical power

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

9. Turn on the unit
Note: Unit should run normally

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

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

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Operation Sheet 16

Checking Door Switch

Objectives: At the end of this practice the learner/trainee will be able to:
o Identify defective door switch using multimeter.

Equipment: - 1 unit
o Multi meter - 1 unit
o Refrigeration Unit
- 1 pc
Tools: 1 pc
o Phillips screw driver
o Flat screw driver - 1 pc
o Lineman’s pliers - 1 pc
o Long nose pliers - 1 pc
o Diagonal cutting pliers
- 1 pair
Personal Protective Equipment: - 1 pc
o Gloves
o Goggles

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Procedures:

1. Unplug the unit.

2. Disconnect wiring connection of air
swing switch.

3. Set the multimeter to Rx1 and calibrate
the meter through zero ohm adjust
knob.

4. Place the test prods across terminals
of the air swing switch.

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