Service and Maintain Domestic Refrigeration and Air-Conditioning (DomRAC) Unit

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.

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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

- 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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Title: Task Sheet #2.2-1

TRACE REFRIGERANT PATH RESTRICTIONS

Performance Criteria Checklist

Performance Criteria Checklist YES NO

Did I..

1.Connect refrigerant hose to the process tube of the

compressor?

2.Connect the pressure gauge to the rubber hose?

3.Check for leaks by using a halide leak detector or by

applying soap bubbles on every fitting?

4.Start the unit?

5.Allow the unit to run for 30 minutes?

6.Observe and check which of the indications below occur

during the operation of the unit?

7.Identify and explain the 3 causes of Path restrictions?

8.Perform housekeeping?

Assessment Result:

Competent Not Yet Competent

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JOB SHEET #2

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.

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c. Test electrical parts and components for short open and ground.
1. Compressor motor6. Door switch
2. Thermostat7. Cabinet heater
3. Overload protector8. Cord and plug
4. Starting relay
5. Cabinet lamp

d. Gather data: Measure load resistance.

e. Identify terminal leads out.

f. Connecting refrigerator circuit.
1. Compressor circuit
2. Cabinet light circuit
3. Heater circuit (if)

LOAD ACTUAL RESISTANCE
Compressor
Cabinet lamp
Cabinet heater

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

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h. Measure line voltage and hook clamp ammeter.
NOTE: To avoid damage of instrument, set selector switch to higher range.

Unit voltage rating Input voltage should Actual line voltage
be

i. Measure line current

Unit Start Run Full load No load Lock
current current current ampere ampere rotor
rating 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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Task Sheet #2.2-1

Title: Connecting Domestic Refrigerator, Frost-Type

Performance Criteria Checklist YES NO

Did I..

1.Prepare tools, instrument and materials?

2.Interpret electrical diagrams?

3.Gather data: Measure load resistance?
4.Identify terminal leads out?

5.Connecting refrigerator circuit?

6.Test electrical circuit connection for short, open and ground?

7.Measure line voltage and hook clamp ammeter?

8.Measure line current?

9.Energize and operate the unit, making sure that it is not

grounded?

10.Turn off thermostat and unplug the unit after
commissioning?

Assessment Result:

Competent Not Yet Competent

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JOB SHEET #3

Connecting Drinking Fountain

D. I. Interpret Diagrams

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.

A. 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

B. Gather data

 Measure load resistance

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Table 1. Measuring load resistance Resistance

Load
Compressor
Condenser fan motor
Power light indicator

E. Interpret Diagrams

F. 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

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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 Input voltage Actual voltage
rating should be

10%

H. Energize and operate the unit.
NOTE:Turn off thermostat before plugging the unit.

I. Commissioning

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

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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Task Sheet #2.2-1

Title: Connecting Drinking Fountain

Performance Criteria Checklist YES NO

Did I..

1.Prepare tools ,instruments and materials?

2.Interpret Diagrams?

3.Connect drinking fountain circuits?

4.Test circuit for short, open and grounded before energizing?

5.Measure line voltage and hook up clamp ammeter?

6.Energize and operate the unit?

7.Turn off thermostat and unplug the unit?

8.Return tools, instrument and materials to the tool room?

9.Clean work areas?

Assessment Result:

Competent Not Yet Competent

JOB SHEET #4
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 Date: Developed Date: Revised Page #

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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. VOLT FLA Actual
resistance
LOAD

1. Compressor
2. Evaporator Fan

motor
3. Defrost heater
4. Condenser F. M.
5. Cabinet lamp
6. Cabinet heater

V. IDENTIFY & MARK TERMINAL LEADS OUT

 Compressor

 Condenser fan motor

 Evaporator fan motor

 Defrost heater

 Defrost timer

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 Thermostat
 Lamp and switches

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

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VII. TEST ELECTRIC CIRCUIT FOR SHORT, OPEN & GROUNDS

Control Position Test Point Reading Actual
1. OFF should be resistance

2. ON Load line Infinity/cabi
3. Defrost net/ heater

Load line Compressor

Load line 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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Task Sheet #2.2-1

Title: Connecting Domestic Refrigerator (No-Frost)

Performance Criteria Checklist YES NO

CRITERIA

Did I..

PREPARETOOLS, INSTRUMENTS AND MATERIALS?

INTERPRET ELECTRICAL DIAGRAM?

TEST ELECTRICAL PARTS FOR SHORT,OPEN AND GROUNDS?

MEASURE LOAD RESISTANCE?

IDENTIFY & MARK TERMINAL LEADS OUT OF FAN MOTORS?

CONNECT NO-FROST REFRIGERATOR CIRCUITS?

TEST ELECTRIC CIRCUIT FOR SHORT, OPEN & GROUNDS?

MEASURE LINE VOLTAGE & HOOK CLAMP-AMMETER?

ENERGIZE & OPERATE THE UNIT?

COMMISSIONING/GATHER DATA?

TURN-OFF CONTROL & UNPLUG UNIT?

RETURN TOOLS, INSTRUMENTS & MATERIALS TO THE TOOL ROOM?

CLEAN WORK AREA?

Assessment Result:

Competent Not Yet Competent

JOB SHEET #5
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

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2. clamp ammeter

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

II. PROCEDURES:
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

NOTE:Replace defective parts.

4. Identify compressor parts.

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Data Terminal Arrangement
1-2= C=
1-3= S=
2-3= R=

5. Identify fan motor. Plotting Method
Data

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

6. Identify air con switch terminal.

Switch Terminals
Position

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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

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.

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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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Task Sheet #2.2-1

Title: Connecting Window Type Air-conditioner
Performance Criteria Checklist

Performance Criteria Checklist YES NO
Did I..

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

3.Identify compressor parts?

4.Identify fan motor?

5.Identify air con switch terminal?

6.Connect air con circuit?

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

8.Measure line voltage and hook up clamp ammeter?

9.Measure line current and record reading at table above?

10.Turn off and unplug unit after commissioning?

11.Keep tools and materials to tool room and clean the work

area?

Assessment Result:

Competent Not Yet Competent

JOB SHEET #6
TITLE: 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

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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 Date: Developed Date: Revised Page #

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 kid bubble solution

V. PROCEDURES:
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

Task Sheet #2.2-1

Title:Pressurizing and Leak Testing (Window-Type Air-Conditioner

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Performance Criteria Checklist YES NO

Did I..

1.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?

2.Open nitrogen tank service valve and regulate the pressure

to a minimum of 50 psi and a maximum of 150 psi?

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

contaminants?

4.Open pressure gauge hand valve and pressurize the system

of about 50 psi or until indicates the recommended pressure

for leak testing?

5.Observe pressure reading for changes in 5 to 30 minutes and

perform leak testing?

6.Apply solution using soft brush or spray it on, start at the

gauge set, and apply on the system joints and fittings?

7.Look for leaks around all fittings and connectors, evaporator

and condenser coils, leak are exposed when bubble formed?

8.Mark leak locations so you can make needed repair?

9.Vent the nitrogen charge to the atmosphere and proceed to

evacuation procedures ?

Assessment Result:

Competent Not Yet Competent

Information Sheet # 5.2-2

Learning Objectives: In a refrigeration and air conditioning shop scenario,
the trainee will be able to

INTRODUCTION:

Refrigeration machinery may not require major regular maintenance
when small problems are detected and corrected before they become big
problems. The reliability of the system can be maintained through periodic

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inspection by a qualified refrigeration man. His services must be utilized and his
recommendation must be acted upon.

Shown below is a typical refrigeration system with a refrigeration man
doing visual inspection as a means of preventive maintenance or doing a
maintenance check-up of the system.

Operating Data:

These are the basics used by a refrigeration man in troubleshooting a system.

An example of operating data of a motor is shown below:

1. Motors are identified from the information
in the rating plate. This includes:

- Maker’s name or trade mark.
- Type of supply, e.g., 3-phase,

38-0 V, 50 cycles.
- Rated power, e.g., 5 Hp.
- Rating, e.g., continuous operation.
- Speed, e.g., 1450 rev/mm.
- Serial number of motor.

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- Frame reference number.
- Additional information.

Check Head or Suction Pressures:

2. Install the gauge manifold set, as shown.

NOTE:

Refer to L.E. “Gauge and Manifold Set” if
necessary.

3. Head pressure should not exceed
60 psi. (4.20 kg/cm2), as shown.

4. If head pressure exceeds 60 psi
(4.20 kg/cm2), it is possible that the
condenser is clogged and needs
cleaning. Clean the condenser as
shown.

Refer to the L.E. on “Cleaning, Removing
and/or Replacing Condensers” if necessary.

Check the Refrigerant Charge in the System: Date: Developed Date: Revised Page #

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5. A popular method to check for
refrigerant charge is to mount a
glass sight gauge in the liquid
line, as shown.

1. Bubbles indicate that there is insufficient
refrigerant.

7. Add refrigerant.
NOTE:

Refer to L.E. “Charging the System with
Refrigerant” if necessary.

8. Checking the Motor for Excessive Temperature

NOTE:
Do not use your hand to check the temperature
of the motor.

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Use a thermometer and check the reading
against the allowable temperature shown
on the name plate.

1. The temperature of the motor should not rise
more than 40ºC (72ºF) over room temperature.

Checking for Leaks in the Suction Valve and Discharge Valve
To test for leaks on the low pressure side of a
compressor, such as at the gaskets, at the suction
service valve, or at the crankshaft seal, one may
use one of two methods:
2. Close the suction service valve and draw as

high a vacuum on the compressor as possible.
Then turn the discharge service valve all the
way in.

3. Keep the compressor running. If the head
pressure gradually rises, it means that air
is being drawn into the low side off the system.

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A better way is to balance the pressures in the
crankcase and turn the discharge service valve
all the way in, as shown.

4. Remove the discharge service valve gauge plug
and connect a 250 mm length of copper line, as
shown.

15. Immerse the copper line into a glass bottle
partly filled with oil, as shown.

16. If the tube discharges gas continuously as Date: Developed Date: Revised Page #
shown by air bubbles it means air is being
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admitted to the low side of the compressor.

17. If there are no leaks, the bubbling will stop immediately
after the compressor is started.

Task sheet #2.

Title: Visual inspection as a means of preventive maintenance or doing

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a maintenance check-up of the system YES NO

Performance Criteria Checklist

Did I..

1.Identify data of motor based from the information in the

rating plate?

2.Check the Refrigerant Charge in the System?

3.Use a thermometer and check the reading against the

allowable temperature shown on the name plate?

4.Close the suction service valve and draw as high a vacuum

on the compressor?

5.Then turn the discharge service valve all the way in?

6.Balance the pressures in the crankcase by turning the

discharge service valve all the way in?

7.Remove the discharge service valve gauge plug

and connect a 250 mm length of copper line?

8.Immerse the copper line into a glass bottle partly filled with

oil?

Assessment Result :

Competent Not Yet Competent

Assignment Sheet

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TITLE : ACCOMPLISHSERVICE AND MAINTENANCE REPORT

1. Obtaining operating data of the equipment ______ _ ____

2. Checking the head and suction pressure ______ _ ____

3. Checking the refrigerant charge in the system ______ _ ____

4. Checking motor for excessive temperature ______ _ ____

5. Checking for leaks in the suction valve and ______ _ ____

discharge valve

Task Sheet #2.2-1

Title: TITLE : ACCOMPLISHSERVICE AND MAINTENANCE REPORT

Performance Criteria Checklist YES NO

Did I..

1.Obtain operating data of the equipment ?

2.Check the head and suction pressure?

3.Check the refrigerant charge in the system ?

4.Check the motor for excessive temperature ?

5.Check for leaks in the suction valve and discharge valve ?

Assessment Result

Competent Not Yet Competent

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Information Sheet # 5.2-1

REPAIRING / REPLACING DEFECTIVE COMPONENTS OF
WINDOW TYPE AIR-CONDITIONING AND DOMESTIC
REFRIGERATION SYSTEM

Learning Objectives: In an air conditioning shop scenario, the trainee will
be able to repair / replace the defective components air conditioning units.

Physical Replacement:

1. Turn the air conditioning unit off and unplug the Power Cord from
the machine and the wall socket.

2. The rear Circuit Breaker Panel (Figure 1-A) must be free before
removal of the Main Power Supply. This is done by removing the
two Phillips head screws (Figure 1-B) at the top of the Circuit
Breaker Panel. Once the screws are removed, carefully lay the entire
Panel inside the Power Supply Unit.

3. Disconnect the 2 power plugs (Figure 2-C) on the Main Power
Supply, located under the center and to the rear of the MACHINE.

WARNING! THE POWER SUPPLY UNIT IS VERY HEAVY. REMOVING AND
REPLACING THE POWER SUPPLY REQUIRES TWO PEOPLE, ONE TO HOLD
THE UNIT AND ONE TO REMOVE AND REPLACE THE RETAINING NUTS.

4. While holding the Power Supply Unit firmly in place, unscrew the
four retaining screws (Figure 2-D) holding the Power Supply Unit to
the machine.

5. Carefully lower the Power Supply Unit and take it out from under
the machine.

6. Unplug the 2 white connectors (Figure 3-E) on the 5/12 VDC Power
Supply Printed Circuit Board.

7. Remove the four Phillips head screws (Figure 3-F) holding the
5/12VDC Power Supply into the Main Power Unit.

8. Remove the 5/12VDC Power Supply from the Power Supply Unit.

9. Install new 5/12VDC Power Supply with the 4 Phillips head screws
removed in step 7.

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10. Reinstall the 2 white connectors onto the 5/12VDC Power Supply.

11. Reinstall the Main Power Supply into the machine using the four
retaining screws removed in step 4.

12. Reconnect the 2 power plugs to the Main Power Supply.

13. Pull the Circuit Breaker Panel to the outside of the machine Chassis
and secure the bottom of the Panel in the latch bracket at the
bottom of the opening so that the Panel is held parallel to the
ground.

Voltage Adjustment:

14. Look through the Circuit Breaker Panel opening and locate the Blue
Wheel, marked R-24, on the 5/12VDC Power Supply. This is the
voltage adjustment potentiometer for the 5 volts DC.

15. Remove the locking screw holding the Right Shroud Arm in place
and raise the Arm to its full up (locked) position.

16. Look to the right rear of the Mother Board (This is the Circuit Board
laying on the chassis that was just exposed by raising the Shroud
Arm) and locate the voltage test points, TP1 (Gnd) and TP2 (+5v).

17. At this time plug the Power Cord into the machine and the wall
socket. (Use extreme caution not to touch the circuit breaker wires
or allow the wires to touch the machine. These wires carry 110
VAC).

18. Place the probes from the Digital Voltmeter into TP1 and & TP2
(Black to TP1 and Red to TP2). Use caution that the probes only
touch TP1 & TP2.

19. Turn on the machine.

WARNING! POTENTIALLY DANGEROUS VOLTAGES EXIST INSIDE THE
POWER SUPPLY UNIT. DO NOT TOUCH ANY COMPONENTS WHILE
ADJUSTING THE VOLTAGE.

20. Using a small Slotted screw driver, adjust the potentiometer (R-24)

so that the voltage indicated on the Digital Voltmeter reads 5.10
volts DC, +/- 0.02 volts.

21. After voltage adjustment, turn the machine off, unplug the Power
Cord from the Circuit Breaker Panel and reinstall the Panel to the
rear of the machine using the screws removed in step 2.

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22. Lower the Shroud Arm and secure in place.

23. Plug the Power Cord into the machine, turn it on, and perform a
test sew out.

HANDLING AND STORAGE OF REFRIGERANTS

The following shall be observed when handling and working with refrigerants:

7.1 Color-coding for refrigerant cylinders shall be maintained for new
refrigerants (although these are concerns of the manufacturers). Refer

to Annex 12 for refrigerant cylinder color assignments.

7.2 Refrigerant manufacturer’s recommended procedures shall be followed
when handling refrigerants.

7.3 Refrigerant containers/cylinders shall be stored in a cool place or
under a roof to protect it from weather extremes, away from fire risk
and direct sunlight.

7.4 Extra care shall be taken not to drop refrigerant containers/cylinders
that may damage the container or its valve.

7.5 When not in use, container valves shall be closed, the valve outlet
cover nut fitted and the valve protection cover replaced.

7.6 While charging, refrigerant containers/cylinders shall not be connected

to a system of higher pressure or temperature to prevent back flow of
refrigerant to the container/cylinder.

7.7 Cylinders intended for a certain type of refrigerant shall not be filled
with another type unless they are properly vacuumed and previous
refrigerant contents are totally extracted, then properly labeled.

7.8 Refrigerant cylinders shall not be over-filled.

7.9 Calibrated weighing scale should be used when filling a cylinder with
extra consideration on the allowable on the available weight capacity
(refer to Annex 6).

7.10 Leaks on refrigerant cylinder valves shall be checked and repaired
before storing in a ventilated area and on a vertical position.

7.11 Establish proper leak testing routine on charging hoses and refrigerant
handling equipment.

7.12 Thorough check-up of refrigerant cylinders shall be done first before
refilling.

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7.13 Refrigerant cylinders shall conform to relevant PNS.

7.14 Storage tank relief valves shall be checked to ensure that they are not
leaking (shall conform to relevant PNS).

7.15 Pump seals of filling machines shall be regularly checked for leaks.

7.16 Charging lines shall be kept as short as possible and be fitted with
either check valves or isolation valve near the end of charging lines.

7.17 Wherever possible, use quick disconnect fittings having one-way valve
in transferring or working with refrigerants.

7.18 Use Personal Protective Equipment (PPE), such as side shield
glasses/goggles, gloves, jackets and safety shoes when handling
containers.

7.19 Never apply direct flame or live steam to a container or valve.

7.20 Never refill disposable cylinders.

7.21 Never use a lifting magnet or sling (rope or chain) when handling
cylinders.

7.22 Never use cylinders for rollers, supports, or any purpose other than to
contain the refrigerant.

7.23 Protect cylinders from any object that will result in a cut or other
abrasion in the surface of the metal.

7.24 Never tamper, repair or alter the valves or the safety devices of the
cylinders.

7.21 Never force connections that do not fit. Make sure the threads on the
regulators or other auxiliary equipment are the same as those on the
cylinder valve outlet.

7.25 Keep valves tightly closed and valve caps and hoods in place when the
cylinders are not in use.

7.26 When in doubt, use electronic refrigerant identifier (will be available to
all Regional EMB offices and TESDA accredited training institutions
nationwide) to analyze its composition.

7.27 Avoid skin contact with the refrigerant for it may cause frostbite.

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Lubricants for alternative refrigerants:

1. An important consideration in the development of hydro
chlorofluorocarbon (HCFCs) and hydro fluorocarbons (HFCs) as
alternative refrigerants is the testing of oils for solubility, stability,
lubricity with the refrigerant, and compatibility with materials of
construction. Testing will determine which lubricants can be used in
current systems and what changes are required.

2. In general the ternary blends and HCFCs can be used with oils that are
commercially available; however, some development work may be required
to optimize performance. Applications with HFCs require the development
of new oils. The desirable properties for developmental use are:

• Acceptable solubility with the refrigerant (ideally, single phase over a
broad temperature range);

• Acceptable lubricity;

• Good thermal stability for the refrigerant/lubricant combination;

• Acceptable compatibility with system materials (elastomers, metals
and plastics);

• Low toxicity; and

• Commercial availability at a reasonable cost.

3. Listed below are the refrigeration lubricating oils and their characteristics:
Mineral Oil (MO)

• Designed for and miscible in CFC/HCFC

• Very soluble in HC (higher viscosity/superheat can be required

Alkylbenzene (AB)

• Designed for and miscible in CFC/HCFC

• Low viscosity AB is also used in rotary compressors for R-407C

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Polyol ester oil (POE)
• Designed for HFC compatibility
• Soluble in CFC/HCFC/HFC/HC
• High solubility in CFC/HCFC/HC must be considered
Polyalkylene glycol (PAG)

• Designed for HFC compatibility

• Not considered suitable with CFC/HCFC

HFC Oils:

Polyol esters (POE) and Poly alkylene Glycol (PAG)

Polyol esters (POE) oils are developed for stationary refrigeration and air
conditioning (RAC) systems but are also used by some auto manufacturers for
retrofit as they are more tolerant to contaminations than PAG.

• POE oils are sensitive to humidity and will absorb moisture from
ambient air if exposed

• Humidity will drastically reduce stability and reduce lifetime of system

• Careful evacuation and use of nitrogen are essential for long term
reliability

Low viscosity Alkylene Benzene (AB) are used in rotaries for R407C and R410A.

III. Alternative Refrigerant and Lubricants:

1. In selecting ozone-compatible alternatives for CFCs, two molecular
concepts are to be used:

• Eliminate (or at least minimize) C-Cl bonds, and

• Include C-H bonds Date: Developed Date: Revised Page #

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This is in addition to maintaining the desirable physical and physiological
properties already ascribed to the CFCs.

With these criteria set forth, the major CFCs producers, such as DuPont,
Solvay, and ICI, searched the tables of known fluorocarbons in an attempt
to match these properties. From these tables, which are extensive only a
few compounds approximate the physical properties of the existing
CFCs.The following table identifies these compounds:

List of Alternative Refrigerants

Replacement Alternative ODP Main Application
for Refrigerant

R - 11 R - 123 0.02 Water chillers

R - 12 R - 134a 0 Domestic and Commercial
Refrigeration(medium temperature),
fixed and vehicle air-con, water chiller

R - 409A 0.05 Commercial and transport refrigeration

R - 502 R - 404A 0 Commercial and transport refrigeration
R - 22 R - 408A 0.026 Retrofit of existing R - 502 systems
R - 500 0.055 Air-conditioning
R - 22
0 Stationary air-conditioning
R - 407C
0 Stationary air-conditioning
R - 410A
0 Refrigeration
R - 404A Commercial and Industrial
Blends

R - 114 HCFC 124 Chiller application, marine

R - 115 HFC 125 0 Low temperature

R - 12/ R - 22 Hydrocarbons 0 Domestic/Air-conditioners

3. TheR -fa1c1t4ors thHaCtFCha-v1e42bto be considReerfreidgeraintionchoosing an alternative
refrigerant are:
• The refrigerant’s atmospheric lifetime

• The ozone depletion potential (ODP)

• The total equivalent warming index (TEWI) in the intended application

• The refrigerant toxicity and flammability

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• The pressure under which the refrigerant operates
• Its heat transfer characteristics
• Its compatibility with materials used in the system
 Miscibility and compatibility with lubricants

The alarming rate of ozone depletion has led developed and developing countries
to draw up an agreement in 1987, known as the MONTREAL PROTOCOL ON
SUBSTANCES THAT DEPLETE THE OZONE LAYER

The Montreal Protocol on Substances that Deplete the Ozone Layer, 1987

• Governments adopted the Montreal Protocol to reduce and eventually
eliminate the emissions of ODSs.

• The Protocol contained a list of controlled ODS and defined the control
measures to reduce production and consumption of these ODS.

• The Montreal Protocol is a dynamic document with amendments and
adjustments.

The Montreal Protocol on Substances that Deplete the Ozone Layer, 1987 /con’t

• The Protocol entered into force on 1 January 1989.

• To date 186 countries worldwide have committed themselves under the
Protocol to phase out the use and production of ODS.

• Based on “precautionary principle” that enables the world community to
take actions to address a major global environmental problem even before
all scientific, economic and technical questions have been fully resolved.
INSTITUTIONAL ASSESSMENT

Test I. Multiple Choice:

Write your answers in capital letter on your answer sheet.

_____ 1. The function which is to disconnects the motor from the source when
the motor becomes overloaded
a. pressure control

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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

_____ 6. Current and potential relay has 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.

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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

Test II. 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
______ 2. Bellows contact with metal during an
increase in temperature

b. part of thermostat that relays the

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______ 3. Bimetal temperature to the bellows
______ 4. Copper
______ 5. Contact point c. it connects the sensing bulb and
______ 6. Evaporator the bellows.
______ 7. Range adjustment
______ 8. Differential adjustment d. a metal which has a greater
coefficient of expansion than iron

e. the point where the flow is opened
or closed

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

g. the difference between cut-out
and cut-in temperature

h. change within limit

i. snap action

Test II. Enumeration

1. Types of evaporator
2. Types of condenser
3. Classification of condenser
4. Parts of electric motor
5. Four major components of refrigerant circuit

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Test III. ESSAY:

Direction: Answer the following questions briefly

1. What are the functions of an overload protector?
2. Differentiate an external overload protector from an internal
overload protector.
3. Differentiate a starting capacitor from a running capacitor.
4. Explain the function of a starting capacitor.
5. Explain the function of a running capacitor.

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