Servicing & Maintaining Window-Type AC and Domestic Ref Units

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

by the sensing bulb.
2. The bellows will expand or contract

3. The bellows will push the bimetal.

4. The contact will be closed.

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

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 limit.

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.

INSTALLING A THERMOSTAT
In installing the thermostat, manufacturers
always recommend that the sensing bulb
be mounted firmly in the evaporator
surface, as shown.

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STEPS IN INSTALLING A THERMOSTAT
1. Clamp sensing bulb to the evaporator, as

shown.

2. Screw thermostat control into the
refrigerator cabinet, as shown.

3. Install cover, as shown.

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SELF-CHECK #10

A. 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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ANSWER KEY to SELF-CHECK #10

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

B. 1. yes
2. yes
3. yes
4. yes
5. yes
6. yes

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INFORMATION SHEET #10

TYPES AND OPERATING PRINCIPLES OF A DEFROST TIMER

OBJECTIVE:
After completing this Information Sheet, you should be able to:
1. Explain how a defrost timer operates.
2. Explain the importance of a defrost timer in a refrigerating system.

SUPPORT MATERIALS:
If necessary, refer to the following materials:
1. Charts
2. Transparencies
3. Trainer

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.

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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.

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.

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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.

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)

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.

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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 #11

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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OPERATION SHEET #3
OPERATION OF A SEMI-AUTOMATIC DEFROST TIMER

OBJECTIVES:
After completing this Operation Sheet, you should be able to:
- explain the operation of a semi-automatic defrost refrigerator; and
- identify the electrical components of a semi-automatic defrost refrigerator

MATERIALS, AND AIDS YOU WILL NEED
Chart - Wiring diagram of a semi-automatic defrost refrigerator
Trainer – Semi-automatic defrost refrigerator

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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.

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)

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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))

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 #12

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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After completing this Learning Element, a set of tools and instruments will be provided for
you to execute a performance test. Your instructor will record your proficiency using the
checklist provided.

Instructor’s checklist Acceptability
Yes No
1. Checked the wiring circuit ______ ______
2. Tested the thermostat control ______ ______
3. Identified the troubles of the overload protector ______ ______
4. Checked the motor windings ______ ______
5. Observed safety precautions ______ ______
6. Handled tools and equipment safely ______ ______
7. Measured the ampere rating of an operating motor compressor ______ ______

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Learning Outcome #5: Maintain Refrigeration System

Assessment Criteria:
 All parts of refrigerant circuit are checked as per manufacturer’s manual / specifications.
 Refrigerant condition is accurately diagnosed and repaired.
 Completion of work is reported and recorded.
 Correct servicing and maintenance procedures are followed.

Resources:
EQUIPMENT AND MATERIALS:
You should provided with the following:
1. Window-type air conditioning unit
2. Refrigeration unit
3. Leak testing instrument
4. Refrigerant cylinder
5. Vacuum pump motor
6. Brazing equipment
7. Nitrogen gas cylinder
8. Service manuals

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LEARNING EXPERIENCES
LEARNING OUTCOME NO. 5: Maintain Refrigeration System

Learning Activities Resources

1. Study the diagrams in the Information  Information Sheet

Sheet #11 “Window-Type Air-Conditioning

Cycle”

2. Read the Job Sheet “Inspection of  Job Sheet
Refrigerant Circuit after Installation”

2. Do the Self-Check at the end of the Job  Self-Check
Sheet.

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INFORMATION SHEET #11
WINDOW-TYPE AIR-CONDITIONING CYCLE

Checking Refrigerant Charge

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JOB SHEET #6
TRACING REFRIGERANT PATH RESTRICTIONS

OBJECTIVE: After completing this Job Sheet, you should be able to:
- trace refrigerant path restrictions; and
- identify at least three causes of the restriction.

EQUIPMENT, MATERIALS, AND AIDS YOU WILL NEED

QUANTITY UNIT DESCRIPTION
1 Refrigeration unit
1 Pressure gauge
1 Adjustable wrench
1 Leak detector

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INTRODUCTION:
The piping transports the refrigerant from one component in the system to the next. A

restriction along the refrigerant line will show trouble in the system. After tracing and identifying
the cause of the restriction, repairs can be made to restore the proper operation of the system.
1. Connect refrigerant hose to the process

tube of the compressor, as shown.

2. Connect the pressure gauge to the rubber
hose, as shown

3. Check for leaks by using a halide leak
detector or by applying soap bubbles on
every fitting.
Refer to Learning Element “Detecting
Leaks” if necessary.

4. Start the unit by plugging, as shown.

5. Allow the unit to run for 30 minutes.

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Observe and check which of the indications below occur during the operation of the unit.

1. At the start of operation, the unit runs
smoothly as if the system normally
functions. Restriction occurs or begins only
when the evaporator temperature reaches
freezing point.

2. When moisture inside the evaporator tubes
is frozen, it will expand and will cause
partial restriction. During partial restriction,
the pressure gage will indicate pressure
reading lower than the usual evaporator
pressure.

3. When complete restriction occurs, the
reading will indicate vacuum pressure. The
system will defrost.

4. At the start of operation, the pressure
gauge will indicate a pressure reading
lower than the usual evaporator pressure.
There is low temperature from the
condenser down to the filter drier. This is
caused by foreign matter inside tubes that
reduces the pressure of the refrigerant.

5. Frosty or freezing surface at any portion of
the line from discharge to filter drier
indicates restriction. If no frosty surface is
observed in the high-pressure side,
restriction is caused by the filter drier.

6. Special cases of restriction caused by
careless technicians include;

- damaged or pinched tubing, and

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- refrigerant path blocked by melted
solder alloy that penetrated the joints.

7. Effects on system operation are:

At the start of operation, the pressure
gauge will indicate vacuum pressure
reading from pressures higher than
atmospheric down to vacuum pressure; low
temperature of the condenser down to filter
drier. The evaporator will not freeze but will
give a lower temperature.

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SELF-CHECK #13

Check which of the following indicates restrictions:
_____ 1. Frosty or freezing surface
_____ 2. Reading in the pressure gauge indicates vacuum pressure
_____ 3. Leak
_____ 4. Refrigerant path blocked by melted solder alloy

CALL YOUR INSTRUCTOR to ask you to perform a number of exercises in tracing
refrigerant path restriction. He will rate you according to the criteria stated in the instructor’s

checklist below.

Instructor’s checklist Acceptability
Yes No
1. Connected refrigerant hose and gauge ______ ______
2. Pinpointed the location of the restriction
3. Identified the cause of the restriction ______ ______

______ ______

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JOB SHEET #7

Connecting Domestic Refrigerator, Frost-Type

I. TOOLS, INSTRUMENT & MATERIALS

A. TOOLS
1. Set of Pliers
2. Set of screwdrivers
3. Wire stripper

B. INSTRUMENTS / EQUIPMENT
1. multi-tester
2. clamp ammeter
3. refrigerator frost type

C. MATERIALS
1. automotive wire
2. terminal end connectors
3. electrical tape

II. PROCEDURE

a. Prepare tools, instrument and materials.
b. Interpret electrical diagrams.

c. Test electrical parts and components for short open and ground.

1. compressor motor
2. thermostat
3. overload protector
4. starting relay
5. cabinet lamp
6. door switch
7. cabinet heater
8. cord and plug

d. Gather data: Measure load resistance.

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e. Identify terminal leads out. LOAD ACTUAL RESISTANCE
f. Connecting refrigerator circuit. Compressor
Cabinet lamp
1. compressor circuit Cabinet heater
2. cabinet light circuit
3. heater circuit (if)

g. Test electrical circuit connection for
short, open and ground.

Control position Reading should be Actual resistance
Off thermostat Infinity/heater (if)
Close door
Off thermostat Cabinet lamp
Open door resistance
On thermostat Compressor
Close door resistance
On thermostat Compressor
Open door resistance

h. Measure line voltage and hook clamp ammeter.

NOTE: Unit voltage rating Input voltage Actual line
To avoid damage of should be voltage
instrument, set selector
switch to higher range.

i. Measure line current

Unit current Start current Run current Full load No load Lock rotor
rating ampere ampere ampere

NOTE:
Refer unit nameplate rating and table reference for refrigerator.

j. Energize and operate the unit, make sure it is not grounded.
k. Turn off thermostat and unplug the unit after commissioning.

NOTE:
Do not operate compressor in high current to avoid burning the motor windings.

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JOB SHEET #8 Resistance

Connecting Drinking Fountain

I. TOOLS, INSTRUMENTS AND MATERIALS

A. TOOLS
1. Set of Pliers
2. Set of screwdrivers
3. Wire stripper
4. Nut driver

B. INSTRUMENTS/EQUIPMENT
1. multi-tester
2. clamp ammeter

C. MATERIALS
1. automotive wire
2. terminal connectors
3. electrical tape

II. PROCEDURE

A. Prepare the electrical parts and components.

B. Test the electrical parts and components
1. compressor
2. condenser fan
3. thermostat
4. overload protector
5. power and light indicator
6. cord and plug

C. Gather data

 Measure load resistance

Table 1. Measuring load resistance

Load
Compressor
Condenser fan motor
Power light indicator

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D. Interpret Diagrams

E. Connect drinking fountain circuits.

1. Compressor circuit
2. Condenser fan motor circuit
3. Power indicator light circuit

F. Test circuit for short, open and grounded before energizing.

Table 2.

Control position Actual resistance
Off thermostat
On thermostat

G. Measure line voltage and hook up clamp ammeter

NOTE:
To avoid damage to the voltmeter, always set the selector knob to a higher range in
measuring unknown voltage and current.

Table 3. Measure line voltage.

Unit voltage rating Input voltage Actual voltage
should be
10%

H. Energize and operate the unit.

NOTE:
Turn off thermostat before plugging the unit.

I. Commissioning

Unit current Start current Run current Full load No load Lock rotor
rating ampere ampere ampere

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J. After commissioning, turn off thermostat and unplug the unit.

K. Return tools, instrument and materials to the tool room. Clean work areas.

NOTE:
Do not operate compressor motor in a high current to avoid burning the motor
windings.

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JOB SHEET #9

Connecting Domestic Refrigerator (No-Frost)

I. TOOLS, INSTRUMENTS AND MATERIALS

A. TOOLS
1. set of Pliers
2. set of screwdrivers
3. wire stripper
4. wrenches

B. INSTRUMENTS/EQUIPMENT
1. refrigerator unit, no-frost
2. multi-tester
3. clamp-ammeter

C. MATERIALS
1. automotive wire #16 AWG
2. terminal end connector, female
3. electrical tape

II. INTERPRET ELECTRICAL DIAGRAM

III. TEST ELECTRICAL PARTS FOR SHORT, OPEN AND GROUNDS
 Compressor
 Fan motor
 Defrost timer
 Defrost heater
 Thermostat
 Cabinet lamp/switches
 Cabinet heater

IV. MEASURE LOAD RESISTANCE

Table 1.

LOAD V FLA Actual
resistance
1. Compressor
2. Evaporator Fan motor
3. Defrost heater
4. Condenser F. M.
5. Cabinet lamp
6. Cabinet heater

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V. IDENTIFY & MARK TERMINAL LEADS OUT
 Compressor
 Condenser fan motor
 Evaporator fan motor
 Defrost heater
 Defrost timer
 Thermostat
 Lamp and switches

VI. CONNECT NO-FROST REFRIGERATOR CIRCUITS
 Compressor circuit
 Evaporator fan motor circuit
 Defrost circuit
 Cabinet light circuit
 Cabinet heater circuit

VII. TEST ELECTRIC CIRCUIT FOR SHORT, OPEN & GROUNDS

Control Position Test Point Reading Actual
1. OFF Load line should be resistance
Infinity/cabinet
2. ON Load line / heater
3. Defrost Load line Compressor
Defrost heater
ohm

VIII. MEASURE LINE VOLTAGE & HOOK CLAMP-AMMETER

NOTE:
Always set instruments to highest range in measuring unknown electrical quantities.

IX. ENERGIZE & OPERATE THE UNIT

NOTE:
Do not energize if circuit is shorted, open or grounded.

X. COMMISSIONING/GATHER DATA

NAMEPLATE RATING ACTUAL READING

HP V FLA NLA LRA V A

XI. TURN-OFF CONTROL & UNPLUG UNIT
XII. RETURN TOOLS, INSTRUMENTS & MATERIALS TO THE TOOL ROOM
XIII. CLEAN WORK AREA

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JOB SHEET #10

Connecting Window-Type Air-Conditioner

I. TOOLS, INSTRUMENTS AND MATERIALS

A. TOOLS
1. Set of Pliers
2. Set of screwdrivers
3. Wire stripper
4. Soldering Iron
5. Wire crimper

B. INSTRUMENTS/EQUIPMENT
1. multi-tester
2. clamp ammeter

C. MATERIALS
1. automotive wire
2. terminal connectors
3. electrical tape
4. soldering lead
5. plastic cable tie

II. PROCEDURE

1. Prepare tools and materials.
2. Interpret air con electrical wiring diagrams.

3. Test electrical parts/components for short, open and ground.

3.1 Compressor 3.6 OLP

3.2 Air swing motor 3.7 Fan motor

3.3 Air swing switch 3.8 Thermostat

3.4 Starting relay 3.9 Capacitor

3.5 Cord and plug 3.10 A/C switch

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NOTE:
Replace defective parts.

4. Identify compressor parts.

Data C= Terminal Arrangement
1-2= S= Plotting Method
1-3= R=
2-3= Terminals

5. Identify fan motor.

1-2= Data
1-3= 2-4=
1-4= 2-5=
1-5= 3-4=
2-3= 3-5=
4-5=

6. Identify air con switch terminal.

Switch
Position

NOTE: C – close contact
O – open contact

7. Connect air con circuit.
7.1 Fan motor circuit
7.2 Compressor circuit
7.3 Air swing circuit

NOTE: Do not energize if shorted, open or grounded. Call the instructor for assistance.

8. Test air con circuit connection for short, open and ground.

Switch Position Actual Actual Current
Resistance

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NOTE: Fan position – High resistance
Cool position – Low resistance
Off – Infinity

9. Measure line voltage and hook up clamp ammeter.

Actual Voltage Name Plate Voltage should
voltage be

10% nameplate

10. Measure line voltage and hook up clamp ammeter.

NOTE:
Turn off A/C switch first before energizing.

11. Measure line current and record reading at table above.
12. Turn off and unplug unit after commissioning.

13. Keep tools and materials to tool room and clean the work area.

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JOB SHEET #11

Pressurizing and Leak Testing (Window-Type Air-Conditioner)

I. PREPARATION OF TOOLS, INSTRUMENTS, EQUIPMENT, MATERIALS AND
PERSONAL SAFETY EQUIPMENT

A. TOOLS
1. Tube cutter
2. Mechanical pliers
3. Tube reamer
4. Service ratchet wrench
5. Swaging tools
6. File
7. Brush

B. INSTRUMENTS/EQUIPMENT
1. Nitrogen equipment
2. Gauge manifold
3. Oxy-acetylene
4. Window A/C unit

C. MATERIALS
1. Access valve
2. Silver rod
3. Silver brazing flux
4. Leak detecting fluid (soap solution)

D. SAFETY GADGETS
1. Goggles
2. Gloves

II. INFORMATION

Once the refrigerant has been removed from a system and the system has been
assembled or repaired, the system must be pressurized for leak testing.

Pressurizing - a process of charging dry nitrogen or refrigerant in a recommended
system pressure for leak testing.

Dry Nitrogen - used for pressurizing refrigerator and air conditioning mechanical system
for leak testing or sweeping system lines during certain soldering or brazing procedures.

Leak Testing - a process of determining leakage in the refrigeration and air conditioning
system.

METHODS OF LEAK TESTING

1. Using soap solutions
2. Using halide leak detector
3. Using electronic leak detector

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III. PROCEDURES IN PRESSURE-TESTING OF A REFRIGERATION SYSTEM

1. Install service access valve to the suction line and discharge line

2. Conned gauge manifold hoses to the system, red hose for discharge service line and
yellow hose for the nitrogen regulator out port and dose gauge hand valves.

NOTE: Do not overtight the hose fittings (finger tight only) to prevent damage of hose 0
rings.

3. Open nitrogen tank service valve and regulate the pressure to a minimum of 50 psi and a
maximum of 150 psi.

4. Purge the air in center fittings of a yellow hose to remove air contaminants.

5. Open pressure gauge hand valve and pressurize the system of about 50 psi or until
indicates the recommended pressure for leak testing.

NOTE: Pressurizing a system must be done gradually and keep the pressure at the
recommended level while leak testing.

6. Observe pressure reading for changes in 5 to 30 minutes and perform leak testing.

NOTE: A drop of pressure indicates leakage.

IV. LEAK TESTING WITH SOAP SOLUTIONS

After system has been pressurized with nitrogen use a soap solution for leak testing
electronic leak detector and halide leak detector wilt not response to nitrogen

Leak detecting fluid
 diluted household detergent
 kid bubble solution

V. PROCEDURE

1. Apply solution using soft brush or spray it on, start at the gauge set, and apply on the
system joints and fittings.

2. Look for leaks around all fittings and connectors, evaporator and condenser coils, leak
are exposed when bubble formed.

3. Mark leak locations so you can make needed repair.
4. Vent the nitrogen charge to the atmosphere and proceed to evacuation procedures if no

leakage is found.

VI. COMMISSIONING

Type of Unit Pressure (PSI) Pressure Diff.
(PSI)
before after

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COMPETENCY ASSESSMENT
LO #1 Clean and replace air filter.
ACTIVITY SHEET: Clean and replace air filter

Check your mastery of learning outcome #1 by demonstrating how to clean air filter based
on the instruction stated in the service manual

Given the actual unit:
1. Make a list of tools and materials needed in cleaning the air filters following the format In
information sheet #1.
2. Demonstrate how to clean and replace air filter of an air conditioner.

SELF-CHECK:

Check your mastery of learning outcome 1 by completing the questions below. Do not
answer on this test booklet. Write your answers on a piece of paper.
Answers the following:
1. Enumerate the steps on how to remove the air filter of the air-conditioner units?
2. If you would be removing the air filter for the first time, what would be the first step you

would follow?
3. What would be the effect of a dirty air filter to the refrigerator?
4. In maintaining the unit, how many time should you clean the air filter?

Code No. Servicing and Maintaining Window-Type Air- Date: Developed Date: Revised Page #

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ASSESSMENT INSTRUMENT (EVIDENCE PLAN)

Competency HVAC/R NC II
Standard:
Ways in which evidences will be collected:
(tick the column) Questioning/
Interview
The evidence must show that the candidate … Demonstration

*Identified and removed parts/ components of the window X X
type air-conditioning and refrigeration in accordance with
standard procedures X X
*Cleaned parts/components in accordance with standard X X
procedures X X
* Checked and inspected all controls/wiring as per X X
schematic diagram and in line with SOP X X
* Checked/inspected all parts of the refrigerant circuit are X X
as per manufacturer’s manual specifications X X
Checked for damage in the air filter in line with standard X X
operating procedures X X
Cleaned the worksite and kept safe in line with work
instructions
*Demonstrated compliance with safety regulations
applicable to worksite operations
*Selected and used appropriate processes, tools and
equipment to carry out tasks
*Communicated effectively with others where applicable
to ensure safe and effective work operations

*FoIlowed correct servicing and maintenance procedures

Prepared by: Instructor Note: *Critical aspects of competency
Checked by: Supervisor Date:
Date:

Code No. Servicing and Maintaining Window-Type Air- Date: Developed Date: Revised Page #

Conditioning/ Domestic Refrigeration Units 138 of 159

ASSESSMENT INSTRUMENT (DEMONSTRATION)

Candidate’s name:

Assessor’s Name:

Competency Assessment Title: Service and Maintain Window-Type Air-Conditioning/Domestic

Refrigeration Units

Qualification: HVAC/R NC II

Date of Assessment:

Time of Assessment:

Instructions for Demonstration:

Instruction is based on the activity sheet.

Materials and Equipment Tick () to show if evidence is
Air conditioner and a refrigerator demonstrated

OBSERVATION Yes No ACTUAL
1.0 – 3.0 5.0
During the demonstration of skills, did the candidate:

1. Replace the filter in accordance with filter
specification? 

2. Clean the filter in accordance to standard? 
3. *Interpret the work instruction to determine the job

requirements? 
4. Observe housekeeping?

5. Observe quality of work?
6. Follow technical specification from manufacturer’s 

manual?
7. Observe work safety?

The candidate’s demonstration was:

Competent  Not Competent 

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COMPETENCY ASSESSMENT

LO #2 Service evaporator and condenser .

SELF-CHECK: Clean evaporator and condenser

Check your mastery of learning outcome 2 by completing the question below. Do not answer
on this test booklet. Write your answers on a piece of paper.

Filling the blanks:

1. ______________________ of a window type air-conditioner unit should be cleaned
annually.

2. Never use ______________________ in cleaning evaporator and condenser it may
cause leaks.

Code No. Servicing and Maintaining Window-Type Air- Date: Developed Date: Revised Page #

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ASSESSMENT INSTRUMENT (QUESTIONING/INTERVIEW)

Candidate’s name: Service and maintain window type air-conditioning/refrigeration unit
Unit of competency: HVAC/R NC II
Competency standards:

Oral/Interview questions Competent response
Yes No

What is air-conditioning?

Why is there no cooling even if the evaporator is clean
and the condenser is unclean or vice-versa?
What precautions would you take in analyzing work
instructions?

How would you make yourself safe at all times?

Feedback to candidate:

Acceptable answers are:

1. [insert suggested answers to questions]

Assessor’s signature: Date

Code No. Servicing and Maintaining Window-Type Air- Date: Developed Date: Revised Page #

Conditioning/ Domestic Refrigeration Units 141 of 159

ASSESSMENT INSTRUMENT (EVIDENCE PLAN)

Competency HVAC/R NC II
Standard:
Ways in which evidences will be collected:
(tick the column) Questioning/
Interview
The evidence must show that the candidate … Demonstration

*Identified and removed parts/ components of the window X X
type air-conditioning and refrigeration in accordance with
standard procedures X X
*Cleaned parts/components in accordance with standard X X
procedures X X
* Checked and inspected all controls/wiring as per X X
schematic diagram and in line with SOP X X
* Checked/inspected all parts of the refrigerant circuit as X X
per manufacturer’s manual specifications X X
Checked evaporator and condenser for damage in line X X
with standard operating procedures X X
Cleaned the worksite and keeping safe in line with work
instructions
*Demonstrated compliance with safety regulations
applicable to worksite operations
*Selected and used appropriate processes, tools and
equipment to carry out tasks
*Communicated effectively with others where applicable
to ensure safe and effective work operations

*FoIlowed correct servicing and maintenance procedures

Prepared by: Instructor Note: *Critical aspects of competency
Checked by: Supervisor Date:
Date:

Code No. Servicing and Maintaining Window-Type Air- Date: Developed Date: Revised Page #

Conditioning/ Domestic Refrigeration Units 142 of 159

ASSESSMENT INSTRUMENT (DEMONSTRATION)

Candidate’s name:

Assessor’s Name:

Competency Assessment Title: Service and Maintain Window-Type Air-Conditioning/Domestic

Refrigeration Units

Qualification: HVAC/R NC II

Date of Assessment:

Time of Assessment:

Instructions for Demonstration:

Instruction is based on the activity sheet.

Materials and Equipment Tick () to show if evidence is
Air conditioner and a refrigerator demonstrated

OBSERVATION Yes No ACTUAL
1.0 – 3.0 5.0
During the demonstration of skills, did the candidate:

1. Clean the evaporator and condenser in accordance
with service procedure? 

2. Use cleaning agent or non-corrosive chemical in 
cleaning and maintaining the evaporator, condenser
coil, plates and fins? 

3. Use high-pressure washer in cleaning evaporator/
condenser with recommended pressure for cleaning? 

4. Observe housekeeping? 

5. Observe quality of work?
6. Follow technical specification from manufacturer’s

manual?
7. Observe work safety?

The candidate’s demonstration was:

Competent  Not Competent 

Code No. Servicing and Maintaining Window-Type Air- Date: Developed Date: Revised Page #

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COMPETENCY ASSESSMENT
LO #3 Maintain fan motor assembly.
ACTIVITY SHEET: Maintain motor and blades

Check your mastery of learning outcome 3 by demonstration on how to maintain motor and
blades from service manual standard.

Given the actual unit:
1. Make a list of tools and materials needed in maintaining motor and blades following the
format in information sheet 1.
2. Demonstrate on how to clean fan motor and blades.

SELF CHECK:

Check your mastery of learning outcome 3 by completing the questions below. Do not
answer on this test booklet. Get extra piece of paper as your answer sheet.
Enumeration:
1. Explain the functions of the fan motor in window type air-conditioners.
2. Give the type of fan motors used in window type air-conditioners.

Code No. Servicing and Maintaining Window-Type Air- Date: Developed Date: Revised Page #

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Information Sheet 1:

SAMPLE FORM

Study the sample form on how to fill it out:

Form 1 Date: _______________
Name: _______________________________

LIST OF MATERIALS, TOOLS AND EQUIPMENT

Item No. Quantity Unit Description
1. 2 Pcs.
2. 3 Pcs. Hammer
Screwdriver

Code No. Servicing and Maintaining Window-Type Air- Date: Developed Date: Revised Page #

Conditioning/ Domestic Refrigeration Units 145 of 159

LO #3 Maintain fan motor assembly.

ASSESSMENT INSTRUMENT (EVIDENCE PLAN)

Competency HVAC/R NC II
Standard:
Ways in which evidences will be collected:
(tick the column) Questioning/
Interview
The evidence must show that the candidate … Demonstration

*Identified and removed parts/ components of the window X X
type air-conditioning and refrigeration in accordance with
standard procedures X X
*Cleaned parts/components in accordance with standard X X
procedures X X
* Checked and inspected all controls/wiring as per X X
schematic diagram and in line with SOP X X
* Checked/inspected all parts of the refrigerant circuit as X X
per manufacturer’s manual specifications X X
Checked fan motor for damage in line with standard X X
operating procedures X X
Cleaned the worksite and keeping safe in line with work
instructions
*Demonstrated compliance with safety regulations
applicable to worksite operations
*Selected and used appropriate processes, tools and
equipment to carry out tasks
*Communicated effectively with others where applicable
to ensure safe and effective work operations

*FoIlowed correct servicing and maintenance procedures

Prepared by: Instructor Note: *Critical aspects of competency
Checked by: Supervisor Date:
Date:

Code No. Servicing and Maintaining Window-Type Air- Date: Developed Date: Revised Page #

Conditioning/ Domestic Refrigeration Units 146 of 159

ASSESSMENT INSTRUMENT (DEMONSTRATION)

Candidate’s name:

Assessor’s Name:

Competency Assessment Title: Service and Maintain Window-Type Air-Conditioning/Domestic

Refrigeration Units

Qualification: HVAC/R NC II

Date of Assessment:

Time of Assessment:

Instructions for Demonstration:

Instruction is based on the activity sheet.

Materials and Equipment Tick () to show if evidence is
Air conditioner and a refrigerator demonstrated

OBSERVATION Yes No ACTUAL
1.0 – 3.0 5.0
During the demonstration of skills, did the candidate:

1. Clean the fan motor and blades in accordance with
service procedure? 

2. Used cleaning agent or non-corrosive chemical in 
cleaning and maintaining the fan motor and blades?

3. Demonstrate correct sequence in disassembling and 
assembling?

4. Observe housekeeping?

5. Observe quality of work?
6. Follow technical specifications from manufacturer’s

manual?
7. Observe work safety?

The candidate’s demonstration was:

Competent  Not Competent 

Code No. Servicing and Maintaining Window-Type Air- Date: Developed Date: Revised Page #

Conditioning/ Domestic Refrigeration Units 147 of 159

ASSESSMENT INSTRUMENT (QUESTIONING/INTERVIEW)

Candidate’s name: Service and maintain window type air-conditioning/refrigeration unit
Unit of competency: HVAC/R NC II
Competency standards:

Oral/Interview questions Competent response
Yes No

Explain the functions of the fan motor in the air-
conditioner.
What is the probable cause of cooling failure, even if the
evaporator and condenser are clean?
What precautions would you take in analyzing work
instructions?

How would you make yourself safe at all times?

Feedback to candidate:

Acceptable answers are:

1. [insert suggested answers to questions]

Assessor’s signature: Date

Code No. Servicing and Maintaining Window-Type Air- Date: Developed Date: Revised Page #

Conditioning/ Domestic Refrigeration Units 148 of 159

COMPETENCY ASSESSMENT

LO #4 Service electrical power and control circuit.

ACTIVITY SHEET: Service electrical control and wiring

Check your mastery of learning outcome 4 by demonstration on how to service electrical
control and wiring.

Given the actual unit:

1. Make a list of tools and materials needed in cleaning the evaporator and condenser
following the format in information sheet 1.

2. Demonstrate on how to test the following:

 Thermostat
 Potential relay
 Overload relay
 Capacitors
 Compressor
 Timer

SELF CHECK:

Check your mastery of learning outcome 4 by completing the questions below. Do not
answer on this test booklet. Get extra piece of paper as your answer sheet.

Enumeration:

1. Explain the functions of the capacitors in the circuit.

2. Explain the operation of an overload protector.

3. Explain the operating principles of the potential relay.

4. Explain the functions of the thermostat.

5. Explain the parts of the multitester.

Code No. Servicing and Maintaining Window-Type Air- Date: Developed Date: Revised Page #

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