Service and maintain package-type air-conditioning units (PACU) / commercial refrigeration equipment (CRE)

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #4 Servicing and Maintaining Package-Type Air-Conditioning Page 49

Unit/ Commercial Refrigeration Equipment

JOB SHEET #4

Test the Efficiency of a Compressor

General Instruction:

The compressor is the heart of a refrigeration system. The system efficiency depends mainly on
the perfect working of a compressor. So it is an essential part for the servicemen to test the
compressor efficiency before he proceeds to any repairing work. This worksheet will guide the
trainees to test the efficiency of a commercial compressor.

Tools, Equipment and Materials:

1. Gauge manifold set
2. Charging lines
3. Ratchet wrench
4. Adjustable wrench
5. Double ended spanner set
6. Soap and brush
7. Refrigeration oil
8. Clean cloth
9. Black tape

Procedure:

1. Prepare system
a. Loosen the service valve system cover by open ended spanner.
b. Check that the service valve stems are all the way out, i.e., backseated.
c. Remove the dead plugs from the half union at the gauge port of the service valve.

2. Connect gauge manifold in the system
a. Connect the compound gauge to the low pressure gauge port opening by means of a
charging line.
b. Connect the pressure gauge to the high pressure gauge port opening by means of
another charging line.
c. Slowly front seat the suction service valve stem.
d. Check oil level in the compressor.
e. Short the electrical terminals of the dual pressure cutout.

Caution: Check that the shorting wire should not touch the body of the dual pressure cutout.

3. Check pressure at low side of the system.
a. Run the compressor for some time and note the readings in the compound gauge
which should be 28”—30’ Hg.
b. Stop the unit and keep an eye on the compound gauge.
c. If the reading remains constant it is sure that there are no leaks in the compressor.
d. The vacuum should stand constant for 24 hrs.
e. Check seal for any leakage of oil.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #4 Servicing and Maintaining Package-Type Air-Conditioning Page 50

Unit/ Commercial Refrigeration Equipment

4. Check pressure at high side of the system
a. If the suction side is O.K. then slowly front seat the discharge service valve stem.
b. Allow dry air to suck through the suction service valve or place a clean cloth soaked
with compressor oil in the suction gauge port opening.
c. Built up a pressure of about 250 P.S.I.G. in the high side of the compressor.
d. Test leaks by applying soap sud to all joints in the high side of the compressor.
e. See that the pressure remains constant in the high side of the compressor.
f. If the discharge pressure decreases and the Suction pressure increases as recorded
in the gauge, it indicates that the reeds are leaky.

5. Test efficiency
a. Release the high side pressure till it is 150 P.S.I.G.
b. in the compressor and check the amount of vacuum the compressor will draw and the
time it takes.
c. Determine the vacuum the compressor can produce against a 150 P.S.I.G. head
pressure. It should not be less than 20” Hg.
d. Check leaks at all joints including seal.
e. Remove gauge manifold set and charging lines.
f. Plug the gauge port openings.
g. Connect the dual pressure cutout properly.

QUESTIONS:

1. Why is it necessary to test the efficiency of a compressor?
2. Why is it advisable to test leak of the low side of the compressor by compressor oil?
3. What would happen when the discharge reed of a compressor is leaky?

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #5 Servicing and Maintaining Package-Type Air-Conditioning Page 51

Unit/ Commercial Refrigeration Equipment

JOB SHEET #5

CHARGE OIL IN THE COMPRESSOR

Tools, Materials and Equipment Needed:

Equipment: Tools:
 PACU/CRE  Ratchet wrench
 System analyzer  Adjustable wrench

Materials: PPE:
 Refrigeration oil of correct grade  gloves
 Clean cloth  goggles
 ¼ flared copper tube

Procedures:

1. Check oil level of the unit through the oil
level sight glass

Oil level
too low

2. Install gauge manifold set in the system
and purge the charging lines

3. Frontseat the suction service valve.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #5 Servicing and Maintaining Package-Type Air-Conditioning Page 52

Unit/ Commercial Refrigeration Equipment

4. Replace center charging line of the gauge manifold with flared copper tube.

5. Start the unit, when the low side gauge
manifold reached 25-28 inches of
mercury, stop the unit.

6. Place the tube into a container of
refrigeration oil. Open the low side hand
valve of the manifold and charge oil into
the compressor.

7. Close low side hand valve and check oil Oil at its
in the compressor through the oil level proper level
sight glass of the compressor.

Note: If oil level seems to be low,
charge the correct amount of oil
by repeating the procedures
above.

8. Remove gauge manifold from the system and let the system run in normal operation.

Caution: Be careful not to spill oil from the system
9. Perform housekeeping.
10. Have your instructor check your work.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #6 Servicing and Maintaining Package-Type Air-Conditioning Page 53

Unit/ Commercial Refrigeration Equipment

JOB SHEET #6

EVACUATE THE SYSTEM

Definition:

Evacuation/Vacuuming is the removal of any gases not recommended for a system or
vessel.

Methods of Evacuation:

A. Deep Evacuation

It involves reducing the pressure in the system to about 50 to 250 microns. It
utilizes two stage vacuum pumps.

B. Triple Evacuation

It is accomplished by
evacuating a system to a low
vacuum, about 1 to 2 mm, and the
allowing a small amount of
refrigerant to bleed into the system
three (3) times. It utilizes single
stage vacuum pump.

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

Tools, Materials and Equipment Needed

Equipment: Instrument:
 PACU/CRE  Vacuum gauge with adapter
 System analyzer
 Vacuum pump

Tools:
 Pliers
 Screw drivers

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #6 Servicing and Maintaining Package-Type Air-Conditioning Page 54

Unit/ Commercial Refrigeration Equipment

Procedures:

1. Remove discharge and suction
service valve cap.

2. Midseat discharge and suction service
valves.

3. Remove service port cap of discharge
and suction service valve

4. Connect gauge manifold into the
system and center connection of the
manifold to the vacuum pump.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #6 Servicing and Maintaining Package-Type Air-Conditioning Page 55

Unit/ Commercial Refrigeration Equipment

5. Turn on the vacuum pump. Open both
hand valves and evacuate the system
long enough or as required.

6. If evacuation is completed, close both
hand valves of the gauge manifold
and turn off the vacuum pump.

7. Observe the pointer that it should not
deflect back to 0 psig. at the compound
gauge. (Note: If the pointer deflects
back to zero psig or less, it indicates
that a leak is present in the system.)

8. Set-up the system for charging.
9. Perform housekeeping
10. Have your instructor check your work.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #6 Servicing and Maintaining Package-Type Air-Conditioning Page 56

Unit/ Commercial Refrigeration Equipment

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #7 Servicing and Maintaining Package-Type Air-Conditioning Page 57

Unit/ Commercial Refrigeration Equipment

JOB SHEET #7

CHARGE REFRIGERANT IN THE SYSTEM (VAPOR CHARGING)

Objectives: At the end of this practice the learner/trainee will be able to:
o Vapor charge a PACU/CRE system

I. Tools, Materials and Equipment Needed

Equipment: Tools:
 PACU/CRE  Adjustable wrench
 System analyzer  Ratchet wrench
  Screw driver

Instruments: PPE:
 Charging/Weighing scale  Goggles
 Thermometer  Gloves
 Clamp ammeter

II. Procedures

The correct amount of refrigerant must be charge in a PACU/CRE system to obtain a
maximum efficiency of the system. The desired temperature and proper functions of the
controls depends on the correct amount of refrigerant charge. This job sheet will guide you to
charge refrigerant in a PACU/CRE system.

1. Check system under vacuum, it
should be between 28 to 30 inches
of mercury.

2. Connect the service cylinder to the
center charging line of the manifold.

Note: Place the cylinder on upright position in
a weighing scale. Record the weight of the
refrigerant cylinder. Purge the refrigerant
hoses.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #7 Servicing and Maintaining Package-Type Air-Conditioning Page 58

Unit/ Commercial Refrigeration Equipment

3. Turn the suction and discharge
service valve on a backseat position
and crack a bit to note down the
suction and discharge pressure.

4. Open the service cylinder valve and
charge refrigerant until the pressure
in the gauge shows above 50-55
psig.

5. Start the compressor and operate it
until enough refrigerant is charge in
system. Control the low side
pressure by opening and closing the
low side hand valve of the gauge
manifold.

Caution: Never allow the system to
run in vacuum.

6. Close refrigerant cylinder valve and
check both suction and discharge
pressure. When pressure seems to
be steady, note down the weight of
the refrigerant cylinder.

7. Check the cabinet temperature,
running current and operation of
pressure control.

8. Perform housekeeping.

9. Have your instructor check your
work.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #8 Servicing and Maintaining Package-Type Air-Conditioning Page 59

Unit/ Commercial Refrigeration Equipment

JOB SHEET #8

TEST LEAKS IN THE SYSTEM

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

Materials, Tools and Equipment:

Materials: - ½m
o Match - 1 pc
o Clean cloth
o Compressor oil of the same specification - 1 set
o Soap suds - 1 set
- 1 set
Tools - 1 set
o Adjustable wrench - 1 pc
o Ratchet wrench
o Double ended spanner - 1 cylinder
o Small paint brush - set
o Charging lines

Equipment
o Halide torch
o Service cylinder containing R12
o Service cylinder containing nitrogen

Instrument
o Gauge manifold

Personal Protective Equipment
o Goggles
o Mask
o Gloves

* - Item is optional

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #8 Servicing and Maintaining Package-Type Air-Conditioning Page 60

Unit/ Commercial Refrigeration Equipment

Procedure:

Make sure that before you perform this activity, you are wearing appropriate personal
protective equipment.

1. Prepare the system

a. Install gauge manifold set into the
system.

b. Place high and low compressor
valve to cracked off to back seat
position.

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

d. Note down the pressure in the system to determine the refrigerant in the system.
Caution: See that a minimum of 50-55 P. S. I. G. is needed for leak test.

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

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #8 Servicing and Maintaining Package-Type Air-Conditioning Page 61

Unit/ Commercial Refrigeration Equipment

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

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

See that the solenoid valve is energized is energized to pass refrigerant throughout the system.

g. Close the hand valve of the gauge
manifold.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #8 Servicing and Maintaining Package-Type Air-Conditioning Page 62

Unit/ Commercial Refrigeration Equipment

h. Close the service valve of the
refrigerant cylinder.

2. Prepare the leak detector
a. Open valve and light gas torch.
b. Adjust for low flame which burns about 1/2 “ above the reactor plate.
c. Let it burn until the reactor plate, a copper element, turns to a cherry red color.
d. Lower flame or even with the reactor plate.

3. Check for leaks in the system by moving the search hose under all joints and
connections in the system including the compressor shaft seal. Be sure to check below
every joint because R12 and R22 refrigerants are heavier than air.

Caution:
a. A halide torch must only be used in a well ventilated area
b. It must never be used in places where explosive gases are present.
c. Never inhale the vapors or fumes from halide torch, they are poisonous.

4. Observe for the change in color of the flame of halide torch.
a. Yellow flame means there is no leak on the part where the search is pointing
b. Green flame means, there is a small amount of leak to where the search hose is
pointing
c. Dark blue or violet flame means there is a large amount of leak to where the
search hose is pointing

5. If the location of the leak cannot be detected, use the soap suds method to pinpoint the
actual location of leak.

6. Let your instructor check your work

7. Perform house keeping

Evaluation:

While performing the activity it is important for you to assess your performance following
the criteria below:

 Joints are checked for leaks
 Actual location of leaks are pinpointed
 Safety practices and proper housekeeping are employed in the conduct of activity

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #9 Servicing and Maintaining Package-Type Air-Conditioning Page 63

Unit/ Commercial Refrigeration Equipment

JOB SHEET #9

REMOVE AND REPLACE FILTER DRIER

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

Materials, Tools and Equipment:

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

Equipment
o Vacuum pump
o Recovery/recycling Machine

Personal Protective Equipment
o Goggles
o Globes
o Mask

* - Item is optional

Introduction:

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

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #9 Servicing and Maintaining Package-Type Air-Conditioning Page 64

Unit/ Commercial Refrigeration Equipment

Procedure:

Make sure that before you perform this activity, you are wearing appropriate personal
protective equipment.

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

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

3. Remove defective filter drier.

4. Install appropriate and new set of
filter drier.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #9 Servicing and Maintaining Package-Type Air-Conditioning Page 65

Unit/ Commercial Refrigeration Equipment

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

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

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

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

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Module
Job Sheet #9 Servicing and Maintaining Package-Type Air-Conditioning Page 66

Unit/ Commercial Refrigeration Equipment

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

10. Open all valves to its normal
operation

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

12. Have your job checked by your
instructor

13. Perform proper housekeeping

Evaluation:

While performing the activity it is important for you to assess your performance following
the criteria below:

 The liquid receiver service valve is front seated properly with the use of proper tools and
equipment before replacing the filter drier

 The remaining refrigerant is recovered before replacing filter drier
 Filter drier has been replaced with the same specs
 The system is ensured to be leak-free
 The unit is charged with refrigerant when needed
 Safety and proper housekeeping is employed during the activity.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Job Sheet #10 Module Servicing and Maintaining Package-Type Air-Conditioning Page 67

Unit/ Commercial Refrigeration Equipment

JOB SHEET #10

REMOVE AND REPLACE OIL SEPARATOR

Objective:

The trainees will be able to:
 Remove and replace oil separator.

General Instructions:

The purpose of an oil separator in the refrigerating unit is to separate oil from the refrigerant
vapor. The oil is highly miscible (soluble with refrigerant) at higher temperature and pressure. It
also serves as a muffler in reducing pulsations to prevent the condensation of the refrigerant
vapor in the oil separator, it should be insulated. This worksheet will guide the trainees to
remove and replace an oil separator in a Commercial Refrigeration system.

Tools, Equipment and Materials:

1. Gauge manifold set.
2. Charging lines.
3. Adjustable wrench.
4. Double ended spanner set.
5. Ratchet wrench.
6. Halide torch.
7. Match box.
8. Goggles.
9. Clean cloth.
10. Service cylinder containing F-12.
11. New oil separator of same capacity.
12. Thermometer.

Procedure:

1. Prepare the system

a. Install gauge manifold set in the
system.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Job Sheet #10 Module Servicing and Maintaining Package-Type Air-Conditioning Page 68

Unit/ Commercial Refrigeration Equipment

b. Purge the charging lines.

c. Check suction and discharge
pressure of the system.

2. Check the system

a. Run the Unit about 10-15 minutes.

b. Observe the cooling effect in the
evaporator.

c. Check the oil level of the
compressor.

Oil at its
proper level

3. Pump down the system
a. Close the receiver service shut off valve.
b. Energize the solenoid valve to open the liquid line passage.
c. Short the electrical terminals of the dual pressure cutout.
Caution: Check the shorting wire should not touch the body of the dual pressure cutout.
d. Run the unit until the compound gauge shows about 2 P.S.l.G. and stop the unit.
e. Wait for some time and see that if the pressure in the compound gauge rises or not.
f. If the pressure rises, start the unit again until the pressure in the suction side comes
to 2 P.S.I.G. and then stop the unit.
Caution: Do not run the unit below 0 P.S.I.G.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Job Sheet #10 Module Servicing and Maintaining Package-Type Air-Conditioning Page 69

Unit/ Commercial Refrigeration Equipment

g. Repeat the process from 3(d) to 3(f) until a steady pressure one or two P.S.I.G. is
obtained in the suction side.

h. Close suction and discharge mainports.
i. Close the hand valve after the oil separator.
4. Remove oil separator
a. Open the discharge line flarenut connections of the oil separator.
Caution: If the pressure seems to be more, open the flarenut slowly.
b. Open the flare connection of the oil separator with the crank case.
Caution: Place a bucket underneath the oil separator to collect oil to be drained from it.
c. Open both the flarenuts at the two ends of the oil separator and remove the oil

separator from the system.
Caution: Do not tilt the oil separator as the oil may come out from the oil separator.
d. Place the oil separator in a safe place.
5. Replace oil separator
a. Connect the oil separator to the flarenuts on the discharge line and tight them
properly.
b. Connect the bottom connection of the oil separator with the crank case and tight it

properly.
Caution: Check that the oil separator is properly insulated.
c. Place the oil separator in such a way that it does not produce strains on the discharge
Caution: Check that the oil separator is vertically connected.
d. Open the receiver service valve a bit and allow the refrigerant to flow.
e. Open suction and discharge mainports.
f. Purge from the outlet of the oil separator.
Caution: Wear goggles while purging.
g. Now open tile receiver service shut off valve and allow the liquid to flow in the system
h. Open the hand valve after the oil separator in the discharge line.
i. Connect the dual pressure cutout properly.
j. Run the unit and cheek suction and. discharge pressures.
k. Charge refrigerant, if necessary.
l. Check oil level in the compressor.
m. Check the cabinet temperature after running at least for one hour.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Job Sheet #10 Module Servicing and Maintaining Package-Type Air-Conditioning Page 70

Unit/ Commercial Refrigeration Equipment

1. Outlet connection
2. Inlet connection
3. Separator
4. Filter
5. Fastening strap
6. Ball float
7. Needle
8. Nozzle
9. Oil pipe connection

Figure 5.

n. Check the operation of the dual pressure cutout.
o. Check leaks by the halide torch after stopping the system.
p. Remove gauge manifold and charging lines and plug the gauge part openings.
q. Close the system covers.

QUESTIONS

1. Why is it necessary to insulate the oil separator properly?
2. What happens if the accumulation of oil in the oil separator is too much?
3. What happens when the float valve of the oil separator collapses?

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Job Sheet #11 Module Servicing and Maintaining Package-Type Air-Conditioning Page 71

Unit/ Commercial Refrigeration Equipment

JOB SHEET #11

REMOVE, REPLACE OR CLEAN THERMOSTATIC EXPANSION VALVE STRAINER

Objectives: At the end of this activity, the learner/trainee should be able to:
1. Install system analysis
2. Pump down the unit
3. Recover refrigerant
4. Remove and reinstall expansion valve
5. Page and link list
6. Add refrigerant
7. Observe system operation
8. Observe safety and wear PPE

Materials, Tools and Equipment:

Materials:
o Expansion Valve
o Refrigerant

Tools
o Wrench
o Flaring tools

Instrument
o Multi-tester
o System analyzer
o Thermometer
o Ammeter
o Leak detector

Equipment
o PPE
o Vacuum pump
o Recovery/recycling Machine

* - Item is optional

Introduction:

Automatic expansion Valve - A refrigerant control valve that maintains a constant
pressure in an evaporation system. These valves are hermetic and cannot be
disassembled for inspection and cleaning. If found defective or inoperative. It is possible
sometimes to adjust the valve until the obstruction is dislodged. The usually work best when
the system is running. If it leaks around the spring housing it will have to be replaced. The
bellows have been permanently damaged.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Job Sheet #11 Module Servicing and Maintaining Package-Type Air-Conditioning Page 72

Unit/ Commercial Refrigeration Equipment

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

protective equipment.

1. Install system analyzer

2. Pump down the unit

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

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Job Sheet #11 Module Servicing and Maintaining Package-Type Air-Conditioning Page 73

Unit/ Commercial Refrigeration Equipment

4. Remove expansion valve and replace it
with a new set (the same specification)

5. Purge the system and test for leak.

6. Run the unit and observe its operation.
Make some adjustment on the valves if
needed. Add refrigerant

7. Have your job check by your instructor

8. Perform proper housekeeping

Evaluation:

While performing the activity it is important for you to assess your performance following
the criteria below:

a. Install system analyzer on suction and discharge valves of the system.
b. Pump down the unit thru liquid receiver service valve.
c. Recover remaining refrigerant thru the use of recovery machine.
d. Remove expansion valve.
e. Reinstall new expansion valve.
f. Purge the system and leak test.
g. Observe system operation by taking data
h. Add refrigerant to the system
i. Perform house keeping.
j. Wear PPE

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Job Sheet #12 Module Servicing and Maintaining Package-Type Air-Conditioning Page 74

Unit/ Commercial Refrigeration Equipment

JOB SHEET #12

SERVICE COMMERCIAL REFRIGERATING SYSTEM

Objective:

The trainees will be able to:
 Service commercial refrigerating system.

General Instructions:

The inherent construction of a refrigerating system is such that any trouble in the system
will be accumulative, i.e., one trouble will cause another. It is, therefore, essential that
refrigerating system should be completely checked over periodically for efficient working of
the system. This worksheet will guide the trainees to service the commercial systems in a
systematic way.

Tools, Equipment and Materials:

1. Gauge manifold set
2. Charging lines
3. Adjustable wrench
4. Double ended spanner set
5. Ratchet wrench
6. Halide torch
7. Match box
8. Clean cloth
9. Amprobe
10. Voltmeter
11. Spirit level
12. Thermometer
13. Wire brush
14. A small blower
15. One packet mild detergent.

Procedure:

1. Inspection
a. Check the proper installation.
b. Check that the cabinet is not exposed to direct sun light.
c. Check the proper ventilation.
d. Check that the machine is very close to an electrical outlet.
e. Check the proper level of the cabinet as well as the machine.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Job Sheet #12 Module Servicing and Maintaining Package-Type Air-Conditioning Page 75

Unit/ Commercial Refrigeration Equipment

CHECKLIST

2. Check and service YES NO

a. All electrical connections are checked according to circuit
diagram so that there should not be any chance of
leakage of electricity.

b. The compressor is checked for any noise.
c. The belt is taken out from the motor and compressor

pulley.
d. The condition of the belt is checked for dryness or

wearing out.
e. The end bearings of the motor are carefully checked.
f. The pulley alignment and the end play are carefully

checked.
g. Motor bearing is lubricated properly.
h. Unit is thoroughly cleaned.
i. The fan and motor pulley are checked for proper

tightness.
j. The line voltage is checked using voltmeter.
k. The current drawn by the motor is checked using an

amprobe.
l. The belt around the motor and compressor pulley is fixed.
m. The belt is checked for alignment and proper tightness.
n. The oil level in the compressor is checked.
o. The seal of the compressor is checked for oil and

refrigerant leakage.
p. The leakage of the entire system is checked by halide

torch.
q. The condenser externally.
r. The suction pressure is checked.
s. The discharge pressure is checked.
t. The cabinet temperature is checked.
u. The operation of the dual pressure cutout is checked.
v. The door gasket is checked for proper tightness.
w. The door binges are lubricated and the latches aid are

adjusted if found necessary.
x. The condition of suction, discharge and liquid lines are

checked.
y. The noise and vibration of the unit is checked and rectified

by using a suitable method.
z. The cabinet is cleaned both internally and externally.

Caution: Refrigeration oil should never be used to lubricate motor bearings.

QUESTIONS

1. What happens if the belt of the compressor and motor is misaligned?
2. What would happen if the seal is leaking of excessive oil?
3. What happens to the “hot gas” as it enters into the evaporator?

Learning Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Outcome #5
Module Servicing and Maintaining Package-Type Air-Conditioning Page 76

Unit/ Commercial Refrigeration Equipment

Learning Outcome # 5 : Maintain Air Distribution System in PACU/CRE.

Assessment Criteria:

 Air distribution system components are checked and airflows are balanced

 Outdoor air supply systems are checked and maintained to meet operational and
regulatory requirements

 Humidifier, equipment is checked, serviced, and sanitized to meet operational and
regulatory requirements

Resources:

 Refrigeration and air conditioning technology book
 Carrier owner’s manual
 Learning Element

Learning Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Outcome #5
Module Servicing and Maintaining Package-Type Air-Conditioning Page 77

Unit/ Commercial Refrigeration Equipment

LEARNING EXPERIENCES

LEARNING OUTCOME NO. 5: Maintain Air Distribution System in PACU/CRE

Learning Activities Resources

1. Read and perform the procedures in the job sheet “Belt  Job Sheet #13
Inspection and Analysis” and answer the questions.

2. Read information sheet “Electric Motors”.  Information Sheet #6

3. Read and perform the procedures in the job sheet  Job Sheet #14
“How to Service Motor Properly” and answer the

questions.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Job Sheet #13 Module Servicing and Maintaining Package-Type Air-Conditioning Page 78

Unit/ Commercial Refrigeration Equipment

JOB SHEET #13

BELT INSPECTION AND ANALYSIS

Tools:

1. Allen wrench
2. Adjustable wrench
3. Steel rule
4. Spirit level
5. Screwdriver

Follow this procedure to inspect a belt:

1. Shut down the power switch and tag it: “Down for maintenance. Do not turn the power
on”. Lock the switch open.

2. Remove the guard and inspect it for wear or damage. Clean grease and debris from the
guard to ensure good ventilation.

3. Notice the temperature. A belt that is too hot to touch just after the drive is shut down has
problems. Find and correct the source of overheating before returning the drive to
service.

4. Inspect the belt. Mark a starting point and work your way around, looking for cracks,
nicks, frays, cuts, or unusual or uneven wear. Replace belts wit excessive wear, cuts, or
missing teeth.

5. Check alignment by removing the belt and laying a straight edge along the outside edges
of both pulleys (see below). Misalignment will increase the chances for premature wear
instability and turnover.

6. Inspect other parts of the drive: motor and pulley mounting, and housing.

ALIGNING A BELT

To prevent premature wear and failure, belt drives must be in proper alignment, with the
shafts parallel and the pulleys in the same plane. If your inspection reveals a misalignment,
corrective action is indicated. A heft can have either angular misalignment and/or parallel
misalignment. (Misalignment can also result from a pulley that is damaged or improperly
mounted.)

1. Angular misalignment can be detected by a long straight edge; a tape measure, string, or
straight board can be substituted on a long drive (see Figure 16). In general, pulley
alignment should be within 1/10 inch per foot (8.4 mm per meter) of the span between
the pulleys. Correct a misalignment by loosening the mounting bolts and rotating one
piece of equipment until both shafts are aligned. Then tighten the mounting bolts and
check for parallel misalignment.

2. To check for parallel misalignment, use a square to show that each shaft is at 90º to the
straightedge. Correct by loosening pulley mounting screws and sliding the pulley until
both edges of both pulleys line up to the straightedge.

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Job Sheet #13 Module Servicing and Maintaining Package-Type Air-Conditioning Page 79

Unit/ Commercial Refrigeration Equipment

Figure 16. Belt alignment.

INSTALLING AND TENSIONING A BELT

Belts must be properly installed and tensioned for good performance. Overtight belts will
cause compressor seals to leak, and bearings and belts to wear prematurely. Loose belts will
slip, heat up, and fail. New belts will stretch slightly, so manufacturers recommend they be
installed somewhat tighter than normal. Always check and retension a new belt after 4 to 24
hours of operation.

After performing the inspections suggested above, use this procedure to replace and tension
a belt

1. Check the number on the belt to order a replacement. If the number is illegible, measure
the length (along the outside) before removing it from the drive. (Check the belt section
later or use a gauge on the sheave to find the section.)

2. Loosen the motor mount and slide the motor toward the compressor to slack off the belt.

3. Remove the old belts without prying them.

4. Install the proper size belt. All belts should be replaced on a multiple drive to ensure that
they pull equally.

5. Slide the motor back into position to tighten the belt.

6. Check and adjust alignment using the above procedure. Check tension by deflecting the
bell at the midpoint between the pulleys. (Rotate multiple-belt drives by hand to seat
them in the grooves and even out the tension before checking tension.) Although belt
tension gauges are available, most mechanics deflect the belt manually and check that

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Job Sheet #13 Module Servicing and Maintaining Package-Type Air-Conditioning Page 80

Unit/ Commercial Refrigeration Equipment

the belt moves a little without having excess slack. Use this rule of thumb: a force of 10
pounds (4.5 kg) should deflect a belt about ½ inch (1.3cm).

7. Tighten motor mounting bolts to the proper torque.

8. After 4 to 24 hours of operation, recheck and readjust the tension.

Figure 17. Fan motor mounting.

ADUSTING THE FAN SPEED

The fan motor is usually equipped with an
adjustable pitch pulley, figure 18. This pulley
can be adjusted to vary the fan speed to
obtain a range of air quantities. To obtain the
desired fan speed, adjust the fan motor pulley
according to the following procedure.

1. Remove the belt from the fan motor
pulley after loosening the motor (as
outlined in the section Adjusting Fan
Belt Tension).

Figure 18. Adjustable speed motor pulley

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Job Sheet #13 Module Servicing and Maintaining Package-Type Air-Conditioning Page 81

Unit/ Commercial Refrigeration Equipment

2. Loosen the setscrew in the movable flange of the pulley. Screw the movable flange in
toward the fixed flange as far as possible. In this position, the pulley gives the maximum
fan speed.

3. Each half-turn of the adjustable flange away from the fixed flange reduces the fan speed.

CAUTION: Under no circumstances should the flange be screwed more than six turns from
the fixed flange. Before tightening the setscrew, insure that the setscrew is over the
nearest flat surface of the pulley hub.

4. Replace the belt and adjust the belt tension as outlined in the following section. It is not
possible to measure the fan speed accurately while the front panel is removed from the
unit. Such fan speed measurement should not be necessary if the preceding instructions
have been followed.

Information Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Sheet #6
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Unit/ Commercial Refrigeration Equipment

INFORMATION SHEET #6

ELECTRIC MOTORS

Introduction

Electric motor converts electrical energy to magnetic energy and then to kinetic energy. The
rotation is caused by repeated attractions and repulsions between electromagnets located in
the motor housing and induced magnets rotating on the armature (rotor).

Practically every motor used in a commercial cooling system operates on alternating current
because the wavelike magnetic field of alternating current (AC) induces a current in conductors
whether or not they are moving in relation to each other (see figure below).

Electric motors have basic parts: the stator (housing or field) and the rotor (armature) which
spins on a shaft inside the housing. When electricity passes through the stator winding, they
become an electromagnet whose field strength rises and falls with the AC waves. This induces
current in the rotor, causing it to become a magnet. The rotor would not rotate if the opposite
poles were positioned next to each other, so motors are designed so the magnetic fields can
never rest in this condition. Due to magnetic attraction and repulsion, the rotor tends to spin,
and as it does, the magnetic field shifts position to cause the attraction or repulsion to continue.

As the AC waves increases in strength during the start of each half of its cycle, the induction
of magnetism in the rotor lags slightly. The time the rotor is fully magnetized, the stator is
already starting to change polarity due to the change in the AC wave, so the field can never line
up with north opposite south.

Information Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Sheet #6
Module Servicing and Maintaining Package-Type Air-Conditioning Page 83

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LUBRICATION AND CLEANING OF MOTOR

Tools: Equipment Supplies
1. Oiler  Blower  Rags/cloth
2. Grease gun  Grease/oil
3. Screw driver
4. Adjustable wrench

Procedure for Lubrication of Motor – Sleeve Bearing

Information Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Sheet #6
Module Servicing and Maintaining Package-Type Air-Conditioning Page 84

Unit/ Commercial Refrigeration Equipment

Information Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Sheet #6
Module Servicing and Maintaining Package-Type Air-Conditioning Page 85

Unit/ Commercial Refrigeration Equipment

Procedure for Cleaning of Motor – Sleeve Bearing

Procedure for Lubrication of Motor – Ball and Roller Bearing

Information Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment
Sheet #6
Module Servicing and Maintaining Package-Type Air-Conditioning Page 86

Unit/ Commercial Refrigeration Equipment

Procedure for Cleaning of Motor – Ball and Roller Bearing

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Job Sheet #14 Module Servicing and Maintaining Package-Type Air-Conditioning Page 87

Unit/ Commercial Refrigeration Equipment

JOB SHEET #14

HOW TO SERVICE MOTOR PROPERLY

Tools and Equipment

1. Screwdriver
2. Clamp ammeter
3. Megger
4. Feeler gauge
5. Speedometer/tachometer

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Assessment Module Servicing and Maintaining Package-Type Air-Conditioning Page 88
Instrument
Unit/ Commercial Refrigeration Equipment

ASSESSMENT INSTRUMENT

EVIDENCE PLAN

Competency HVAC/R NC II
Standard:
Service and Maintain PACU/CRE Equipment
Unit of
Competency: Ways in which evidence will be collected:
[tick the column]
Question/Interview
The evidence must show that the candidate … Demonstration

1. Identified and removed parts/components of PACU/CRE XX
equipment in accordance with standard procedures.

2. Checked and inspected all controls/wiring as per schematic XX
diagrams are in line with SOP.

3. Cleaned parts and components in accordance with standard XX
procedures.

4. Checked refrigerant circuits for condition, leak, insulation and X X
tightness of support brackets.

5. Applied correct servicing maintenance procedures in XX
mechanical and electrical parts of PACU/CRE equipment as XX
per SOP/manuals.

6. Applied proper housekeeping.

7. Demonstrated compliance with safety regulations applicable XX
to worksite operations.

8. Selected and used appropriate processes, tools and XX
equipment to carry out tasks. XX

9. Wear appropriate PPE

10. Communicate effectively with other where applicable to XX
ensure safe and effective work operations.

Prepared NOTE: *Critical aspects of competency
by:
Checked by: Date:
Date:

Unit Service and Maintain Package-Type Air-Conditioning Unit/Commercial Refrigeration Equipment

Assessment Module Servicing and Maintaining Package-Type Air-Conditioning Page 89
Instrument
Unit/ Commercial Refrigeration Equipment

DEMONSTRATION

Candidate name:

Assessor name:

Unit of competency: Service and Maintain PACU/CRE Equipment

Competency standards: HVAC/R NC II

Date of assessment:

Time of assessment:

Instructions for demonstration

Prepare the tools and equipment needed, and have the demonstration in servicing and
repairing clutch system.

OBSERVATION  to show if evidence is
demonstrated

During the demonstration of skills, did the candidate: Yes No N/A

1. Identified and removed parts components of PACU/CRE
equipment in accordance with standard procedures.

2. Checked and inspected all control/wiring as per schematic
diagrams are in line with SOP

3. Cleaned parts and components in accordance with SOP.

4. Checked refrigerant circuits for condition, leaks, insulation
and tightness of support bracket.

5. Applied correct servicing and maintenance procedures on
mechanical and electrical parts of PACU/CRE equipment as
per SOP/manual.

6. Applied proper housekeeping.

7. Demonstrated compliance with safety regulations applicable
to worksite operations.

8. Selected and used appropriate equipment to carry out tasks.

9. Wear appropriate PPE.

10. Communicate effectively with others to ensure safe and
effective work relations.

The candidate’s demonstration was: Not Satisfactory 
Satisfactory 