Troubleshooting Window-Type Air-conditioning / domestic refrigeration systems

COMPETENCY BASED LEARNING MATERIAL

Sector:
HEATING, VENTILATING, AIR-CONDITIONING AND REFRIGERATION (HVAC/R)

Qualification:

RAC Servicing NC II

Unit of Competency:

Troubleshoot and Repair Domestic Refrigeration
and Air-Conditioning (DomRAC) Systems

Module Title:

Troubleshooting Window-Type Air-Conditioning/
Domestic Refrigeration Systems

Technical Education and Skills Development Authority

East Service Road, South Superhighway, Taguig, Metro Manila

Introduction:

The unit of competency “Troubleshoot Window-Type Air-conditioning and
Domestic Refrigeration Systems” contains the knowledge, skills and attitudes
required in a Refrigeration and Air-conditioning course. This is one of the core
modules for National Certificate level II (NC II).

Summary of Learning Outcomes:

On completion of this module you should be able to:

 Plan and prepare for troubleshoot.
 Identify and repair faults / troubles
 Perform refrigerant recovery / recycling and retrofitting / conversion on

domestic refrigeration and air conditioning unit
 Test-run repaired unit

Assessment Criteria

To be able to verify that you are competent enough in this module you must be
able to demonstrate the performance criteria while troubleshooting and repairing
electrical and mechanical system including recovery / recycling retrofitting/
conversion of window-type air-conditioning and refrigeration system.

 Appropriate wiring diagrams, charts and manuals are read and interpreted

 Tools, materials and equipment needed are prepared in line with job
requirements

 Manufacturer's nameplate rating are properly identified

 Correct testing procedures in the components are applied

 Components faults and problems are identified and diagnosed

 Remedial action is undertaken on the identified faults and problems

 HVAC code of practice and safety guidelines on troubleshooting and repair
of electrical system are properly applied

 Test unit pressure and temperature are performed in accordance to work
instructions

 Completed report on trouble shooting and repair of electrical system are
accomplished

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 Refrigeration cycle is explained

 Mechanical parts and functions are identified and described

 Troubleshoot and repair procedure of mechanical system are performed in
accordance with work instructions

 Operating procedures are performed in accordance to unit's manual
procedures

 HVAC code of practice and safety guidelines in troubleshooting of
mechanical system are properly applied

 Test unit pressure and temperature are performed in accordance to work
instructions

 Work documentation is prepared and submitted as per prescribed
procedure

 Good housekeeping and safety practices is applied in line with job
requirements

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Conditions:

The trainee must be provided with the following

Equipment Tools
 R\R machine  Wrench set
 Nitrogen equipment  Tubing tools set
 Oxy acetylene  Pinch Off pliers
 Vacuum pump  File
 Screw driver set
Instruments  Service ratchet
 Multi-tester  Soldering iron
 Gauge Manifold  Wire crimper
 Thermometer  Pliers set
 Electric leak Detector  Wire stripper
 Weighing scale  Crimping pliers
 Clamp ammeter
 Megger Personal Protective Devices
 Vacuum meter  Goggles
 Gloves
Supplies and Materials  Gas mask
 Refrigerant  Safety shoes
 Electrical wire  Working clothes
 Electrical tape
 Terminal end connector Learning Materials
 Access valve  LEs/CBLM on window AC &
 Copper tube Domestic Refrigeration
 Filter/drier, braze type  Text books/Manuals
 Silver rod  Catalogue
 Brazing flux  Brochure
 Rags  Work instructions
 Capillary tube
 Aluminum rod
 Soldering lead
 Wire harness tire
 Filter drier
 Flare fittings
 Refrigerant hose gasket
 Nitrogen gas
 Access valve cap

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Reference Materials:

 Althouse A. D., Turnquist C.H., Bracciano A. F. MODERN REFRIGRATION
AND AIR CONDITIONING, 1992. The Goodheart-Wilcox Company, Inc.

 Institute of Integrated Electrical Engineers. PHILIPPINE ELECTRICAL
CODE, PART 1 2000 Edition. June 2002. Bookman Inc.,

 CODE OF PRACTICE FOR REFRIGERATION AND AIR CONDITIONING
(Philippine Setting. June 2004. Department of Environment and Natural
Resources (DENR)

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About this Competency Based Learning Material

Welcome to the Module on “Troubleshooting and Repairing Window-Type
Air-conditioning and Domestic Refrigeration Systems”. This module contains

training materials and activities for you to complete.

In going through this module, you will follow the “Learning Activity Sheet”.
This Learning Activity Sheet will guide you through different “Instruction Sheets”

that will assist you in performing different learning activities towards the

attainment of the learning outcome.

The instruction sheet may be in a form of:
 Information Sheet - This type of sheet supplies will supply you with

information needed to be able to perform certain
activities.

 Job Sheet - This instruction sheet is designed to guide you
how to do a complete piece of work that will
contribute to the attainment of the learning
outcome.

 Operation Sheet - This instruction sheet will guide you in
performing single basic task, operation or
process in a job.

 Assignment Sheet - The assignment sheet is a guide used to
enhance (follow-up) what you have learned in
the information sheet, job sheet or operation
sheet.

 Work Sheet - Work sheets are the different forms that you will
be filling up in certain activities that you will be
performing.

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This procedure will be repeatedly done until you have completed all the
learning elements in this Competency Based Learning Module or until such time
that you are ready to take the final assessment for this module. You may skip
some learning activities if you are competent enough for the said task.

At the end of this module is a Learner’s Diary. Use this diary to record
important dates, jobs undertaken and other workplace events that will assist you
in providing further details to your trainer or an assessor. A Record of
Achievement is provided for you by your trainer to accomplish once you
complete the module.

Upon completion of this module, ask your trainer to assess you. You will be
given a certificate of completion as proof that you met the standard requirements
(knowledge, skills and attitude) for this module. The assessment could be made
in different methods, as prescribed in the competency standards.

If you have questions, please don’t hesitate to ask your technical
instructor/tool subject instructors for assistance. Your facilitator will always be
available to assist you during the training.

Recognition of Prior Learning (RPL)

You may already have some or most of the knowledge and skills covered in
this module because you have:

 been working for some time
 already completed training in this area.

If you can demonstrate to your trainer that you are competent in a particular
skill or skills, talk to him/her about having them formally recognized so you don’t
have to do the same training again. If you have a qualification or Certificate of
Competency from previous trainings show it to your trainer. If the skills you
acquired are still current and relevant to this module, they may become part of
the evidence you can present for RPL. If you are not sure about the currency of
your skills, discuss this with your trainer.

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Symbols

These symbols are located in the left margin of the module. It illustrates action
which should be taken or resources to be used at the particular stage in this module.

Learning Optional Activity
Outcome

Resources Practice

Reading Activity Self Check

Use Computer Answer Key

View Video Competency
Assessment
Listen to Audio
Tape Safety

Work Sheet

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Reading Activity 1 p.24

Read: Information Plan and Prepare Troubleshooting

Sheet 1:

o This is an informative sheet that discuss about planning and preparing

troubleshooting.

Practice Activity 1 p.41

Perform: Job Sheet 1: Troubleshooting Refrigeration/Air
conditioning Unit

o This is a practice activity that will enhance your knowledge and skills in
troubleshooting

o After performing this activity, let your instructor check your work for
further comments and improvements.

Reading Activity 2 p.42

Read: Information Hermetic Motor Compressor

Sheet 2:

o This is an informative sheet that discuss the basic principles and

operation of hermetic motor compressor

Self-Check p.45

Do: Self-Check 1

o This is to self-evaluate what you have learned about the basic
principles and operation of hermetic motor compressor.

o After answering the questionnaire, you can check your answer with the
answer key on the following page.

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Practice Activity 2 p.47

Perform: Assignment Sheet Identifying Hermetic Compressor
1: Terminal

o This is a practice activity in identifying hermetic compressor terminal
through the given resistances.

Self-Check p.48

Do: Self-Check 2

o This is to self-evaluate what you have learned about identifying
hermetic compressor terminal through the given resistance.

o After answering the questionnaire, you can check your answer with the
answer key on the following page

Practice Activity 3 p.49

Perform: Operation Sheet 1: Determining Hermetic Compressor
Terminal Using Multimeter

o This is a practice activity in determining hermetic compressor terminal
through the use of multimeter.

o After performing the practice activity, ask your instructor to check your
work.

Reading Activity 3 p.50

Read: Information Hermetic Compressor Electrical
Sheet3: Connection

o This is an informative sheet that discusses about different types of
hermetic compressor electrical connection.

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Self-Check p.55

Do: Self-Check 3

o This is to self-evaluate what you have learned about the Different types
of hermetic compressor electrical connection

o After answering the questionnaire, you can check your answer with the
answer key located at the following page.

Practice Activity 4 p.57

Perform: Operation Sheet Connecting Hermetic Compressor
2: (Permanent Split Capacitor Motor)

o This is a practice activity in connecting compressor circuit using PSC
type of compressor motor.

Practice Activity 5 p.59

Perform: Operation Sheet Connecting Hermetic Compressor
3: (Capacitor Start Capacitor Run Motor)

o This is a practice activity in connecting compressor circuit using CSCR
type of compressor motor.

Practice Activity 6 p.61

Perform: Operation Sheet Connecting Hermetic Compressor
4: (Capacitor Start Induction Run Motor)

o This is a practice activity in connecting compressor circuit using CSIR
type of compressor motor.

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Practice Activity 7 p.63

Perform: Operation Sheet Connecting Hermetic Compressor
5: (Resistance Start Induction Run Motor)

o This is a practice activity in connecting compressor circuit using RSIR
type of compressor motor.

Practice Activity 8 p.65

Perform: Operation Sheet Testing Compressor Motor Winding
6:

o This practice activity will enable you to determine the common defects
of hermetic compressor motor such as grounded, shorted and open
winding.

Practice Activity 9 p.68

Perform: Job Sheet 2: Replace Compressor Motor

o This practice activity will enable you to determine the common defects
of hermetic compressor motor such as grounded, shorted and open
winding.

Reading Activity 4 p.71

Read: Information Fan motors

Sheet 4:

o This is an informative sheet that discusses about operating principles of

fan motors, standard color coding and standard terminal leads brought

out.

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Practice Activity 10 p.76

Perform: Operation Sheet Identify Fan Motor Terminals
7:

o This practice activity will enable you to identify fan motor terminals
through color coding, determining untagged terminals of fan motor and
checking conditions of fan motor.

Reading Activity 5 p.81

Read: Information Identifying Capacitors

Sheet 5:

o This is an informative sheet that discusses about operating principles,

types of capacitor used in refrigeration and air conditioning system. It

also deals with connecting capacitors to suit for the capacitance needed

during emergency repairs.

Self-Check p.84

Do: Self-Check 4

o This is to self-evaluate what you have learned about the capacitors.

o After answering the questionnaire, you can check your answer with the
answer key located at the following page.

Practice Activity 11 p.86

Perform: Operation Sheet 8: Testing capacitor using ohmmeter
(Running and Starting Capacitor)

o This practice activity will show how to determine defective capacitor
using multimeter.

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Practice Activity 12 p.90

Perform: Job Sheet Replace Capacitor

3:
o This practice activity will show how to replace defective capacitor from

the unit.

o After this activity, have your instructor check your work.

Reading Activity 6 p.93

Read: Information Selector Switch

Sheet6:

o This is an informative sheet that discusses about operating principles of

selector switch used in air conditioning unit.

Practice Activity 13 p.94

Perform: Operation Sheet 9: Checking Selector Switch

o This activity will show how to check selector switch. It also deals with
identifying selector switch terminals.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Reading Activity 7 p.97

Read: Information Electrical Controls: Current and
Sheet 7: Potential Relays

o This is an informative sheet that explains about operating principles and
connections of current and potential relay in the refrigeration and air
conditioning units.

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Self-Check p.102

Do: Self-Check 5

o This is to self-evaluate what you have learned about current and
potential relays.

o After answering the questionnaire, you can check your answer with the
answer key located at the following page.

Practice Activity 14 p.105

Perform: Operation Sheet Checking Current Relay (Coil Type)

10:
o This activity will show how to identify defective current relay.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Practice Activity 15 p.108

Perform: Operation Sheet Checking Potential Relays

11:
o This activity will show how to identify defective potential relay.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Reading Activity 8 p.110

Read: Information Overload Protector

Sheet 8:

o This is an informative sheet that explains about operating principles and

connections of overload protector in the refrigeration and air

conditioning units.

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Self-Check p.113

Do: Self-Check 6

o This is to self-evaluate what you have learned about overload
protectors.

Practice Activity 16 p.114

Perform: Operation Sheet Checking Overload Protector

12:
o This activity will show you how to check overload protector..

o After performing this activity, let your instructor check your work for
further comments and improvements.

Reading Activity 9 p.116

Read: Information Sheet Temperature Control Switch
9: (Thermostat)

o This is an informative sheet that explains about operating principles and
connections of thermostat in the refrigeration and air conditioning units.

Self-Check p.122

Do: Self-Check 7

o This is to self-evaluate what you have learned about thermostat.

o After answering the questionnaire, you can check your answer with the
answer key located at the following page.

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Practice Activity 17 p.124

Perform: Operation Sheet Checking Thermostat

13:
o This activity will show you how to check thermostat.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Reading Activity 10 p.127

Read: Information Defrost Timers

Sheet10:

o This is an informative sheet that explains about operating principles and

connections of defrost timers in the refrigeration units.

Self-Check p.132

Do: Self-Check 8

o This is to self-evaluate what you have learned about operation of semi
automatic defrost timer.

Reading Activity 11 p.133

Read: Information Sheet Operation of a Semi-Automatic Defrost
11: Timer

o This is an informative sheet that explains about operation of a semi
automatic defrost timer.

Self-Check p.136

Do: Self-Check 9

o This is to self-evaluate what you have learned about operation of semi
automatic defrost timer.

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Practice Activity 18 p.137

Perform: Operation Sheet Testing Defrost Timer

14:
o This activity will show you how to test defrost timer.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Practice Activity 19 p.140

Perform: Job Sheet 4: Replace Defrost Timer

o This activity will show you how to replace defective defrost timer.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Practice Activity 20 p.143

Perform: Operation Sheet Test Air Swing Motor

15:
o This activity will show you how to replace defective air swing motor.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Practice Activity 21 p.145

Perform: Job Sheet 5: Replace Air Swing Motor

o This activity will show you how to replace defective air swing motor.

o After performing this activity, let your instructor check your work for
further comments and improvements.

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Practice Activity 22 p.148

Perform: Operation Sheet Checking Door Switch

16:
o This activity will show you how to check door switch.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Practice Activity 23 p.151

Perform: Operation Sheet Checking Service Cord/Plug

17:
o This activity will show you how to check service cord/plug.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Practice Activity 24 p.153

Perform: Operation Sheet Continuity Test Air conditioning Unit
18: (Power Cord)

o This activity will show you how to troubleshoot the unit by means of
continuity testing.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Reading Activity 12 p.156

Read: Information Sheet Oxyacetylene

12:
o This is an informative sheet that discuss about soldering and brazing

equipment such as oxyacetylene.

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Practice Activity 25 p.159

Perform: Operation Sheet 19: Setting-up Oxyacetylene Equipment

o This Practice activity that will teach you how to set-up oxyacetylene
equipment.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Practice Activity 26 p.163

Perform: Operation Sheet 20: Perform Brazing and Soldering

o This Practice activity that will show you how perform brazing and
soldering.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Practice Activity 27 p.166

Perform: Assignment Sheet 2: Soldering and Brazing Tube
Fittings

o This practice activity that will enhance your knowledge and skills in

brazing and soldering.
o After performing this activity, let your instructor check your work for

further comments and improvements.

Reading Activity 13 p.167

Read: Information Sheet Evaporator

13:
o This is an informative sheet that discuss the basic principles and

operation of evaporator

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Reading Activity 14 p.170

Read: Information Sheet Condenser

14:
o This is an informative sheet that discusses about different types of

condensers.

Reading Activity 15 p.173

Read: Information Sheet Identifying Cleaning and Rinsing
15: Solvents

o This is an informative sheet that discusses about cleaning and rinsing
solvents used in evaporator and condensers

Self-Check p.178

Do: Self-Check 10

o This is to self-evaluate what you have learned about cleaning and
rinsing solvents.

o After answering the questionnaire, ask your trainer for the answer key.

Practice Activity 28 p.179

Perform: Job Sheet 6: Cleaning, Removing and/or
Replacing the Evaporator

o This practice activity will show you how to clean, remove and replace
evaporator.

Practice Activity 29 p.186

Perform: Job Sheet 7: Pressure Washing Finned Evaporator

o This practice activity will help you how to pressure wash finned
evaporator

o After performing this activity, let your instructor check your work for
further comments and improvements.

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Practice Activity 30 p.191

Perform: Job Sheet 8: Straightening Bent Fins

o This practice activity will show some techniques in straightening bent
fins.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Practice Activity 31 p.193

Perform: Job Sheet 9: Cleaning Condensers

o This is a practice activity that will show how clean condensers.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Practice Activity 32 p.195

Perform: Job Sheet 10: Determining Defective Compressor
(Stuck-up and Loss Compression)

o This activity will show how to determine loss compression and stuck-up
compressor motor.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Practice Activity 33 p.197

Perform: Job Sheet 11: Determining Leaky Refrigeration/Air
conditioning System

o This activity will show how to determine leaky refrigeration/air
conditioning system.

o After performing this activity, let your instructor check your work for

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further comments and improvements.

Practice Activity 34 p.199

Perform: Job Sheet 12: Determining Clogged
Refrigeration/Air conditioning
System

o This Practice activity that will show you how determine clogged
refrigeration/air conditioning system.

o After performing this activity, let your instructor check your work for
further comments and improvements.

Reading Activity 16 p.204

Read: Learning Outcome

Information Sheet 16: The Importance of Recovery/Recycling of Refrigerants

Self Check p.211

Do: Self-Check.11
• Check your work with the Answer Sheet

Reading Activity 17 p.213

Read: Information Sheet 17: Identify refrigerants

Reading Activity 18 p.219

Read: Information Sheet 18: Identify refrigerant using identifier

Self Check p.224

Do: Self-Check. 12
• Check your work with the Answer Sheet

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Practice Activity 35 p.228

Practice: Job Sheet 13 - Identify Refrigerant Using Portable Identifier
• Ask permission from instructor
• Prepare equipment, tools and materials
• Observe safety practices
• Maintain cleanliness

Practice: Job Sheet 14 - Identify Refrigerant Using Pressure Temperature
Method

• Ask permission from instructor
• Prepare equipment, tools and materials
• Observe safety practices
• Maintain cleanliness

Reading Activity 19 p.256

Read: Learning Outcome
Study: Information Sheet 19: Assess Unit for Retrofit

Viewing Video Program

View: Ask instructor to assist you setting up the video program
• Video: Back to the Future—Working Safely with Hydrocarbons

Optional Activity

Call Instructor: Discuss other options to attain objectives
• Ask instructor short lecture and demonstration in retrofitting.

Self Check p.264

Do: Self-Check. 14
• Check your work with the Answer Sheet

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Information Sheet 1
Plan and Prepare for Troubleshooting.

Test Unit & Troubleshooting Procedures

Troubleshooting Procedures

There is a close relationship between the terms troubleshooting & servicing.
Troubleshooting is often referred to as analysis of the problem. This analysis is generally
guided by a chart provided by the manufacturer of the equipment. Servicing is the manual
labor needed to correct the problem that was identified in the troubleshooting sequence.

One of the key requirements for service technicians is to follow standard procedure;
the example is as follows;

1. Obtain from the owner a description of the problem,
2. From the problem identified by the owner, determine the possible cause of the

problem,
3. Identify a specific remedy for the problem.

Using standard procedure will save time, money and frustration. Most charts
have three (3) basic columns, heading are;

a. Problem (trouble, complaint)
b. Possible Cause (probable cause, have gas checked….)
c. Remedy (Repair, you may need to…..)

When using the troubleshooting charts, it is important that the technician follow the
chart on a step-by-step basis.

Upon arrival at the location, the technician should become familiar with the system in
questions. The system should be visually inspected and all components and wiring
examined for any evidence of malfunction, the technician should then consider
examination of the system’s electrical wiring & component diagram.

When responding to service call the technician must always approach the problem in
a logical sequence.

 The first step in troubleshooting is to ask the owner/user or operator about the
problem, then inspect, check and test the system using troubleshooting
instrument. Your ability to think the problem of a cooling system is a great asset
in troubleshooting.

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 Your five (5) senses can tell a lot about what is going on a system.

Look: for vibration, gauge reading, current and voltage reading, leaks, broken
or loose parts.

Listen: for compression knocks, valves opening or closing, switches clicking at
the right time.

Feel: feel temperature changes, pipes that are hot when they should be cool, or
vice versa.

Smell: for burned wire insulation, hot parts or belts slipping.
Taste: for food that has spoiled due to vacuum temperatures.

Owner’s Description of Problem

 The first column of the troubleshooting chart normally lists the problem. This
column would be the complaint given to the service technician by the owner –
usually in general terms.

 The technician logins troubleshooting by carefully listening to the owner’s
complaint.

Checking Possible Cause

 The next step would be for the technician to check the possible cause column
& to analyze this listing in terms of the major components of the system.

 After a through investigation of the possible cause’s column, the technician
proceeds to identify the parts of the system listed as the possible cause of the
problem or symptom. The technician should then be able to determine a
specific cause or malfunction & to identify the specific faulty part.

Suggested Remedy

 The final column on the troubleshooting chart may have a heading of remedy.
This is the third (3rd) step when using troubleshooting chart. The technician will
perform the appropriate task for this column. The actual procedure will vary
depending upon the specific remedy selected, the type of part or device being
checked & the specific system. Basic service & safety procedures are always
followed as the technician repairs the system.

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Information Sheet

Trouble Probable Cause Suggested Remedy
Complaint
Problem Cause Repair

Have You Checked You May Need To

Problem Possible Cause Remedy
F. Unit operates 1. Fix leak, add charge.
1. Shortage of refrigerant 2. Clean contacts or
long or 2. Control contacts stuck
continuously replace control.
or frozen closed. 3. Determine fault and
3. Refrigerated space
correct.
has excessive load or
poor insulation 4. Replace with larger
4. System inadequate to system.
handle load
5. Evaporator coil iced 5. Defrost.
6. Restriction in 6. Determine location
refrigeration system
7. Dirty condenser and remove.
8. Filter dirty 7. Clean condenser.
8. Clean or replace.

Troubleshooting Chart

 Servicing must always accomplished through the use of the proper tools,
gauges, electrical analyzing equipment & other necessary equipment.

 The use of troubleshooting charts is relatively simple. The technician must
understand it is a helpful map which leads from step 1 – Problem, step 2 –
Possible Cause, & step 3 – Remedy.

 One must be very careful to utilize the specific troubleshooting chart the
manufacturer of the equipment being serviced. Troubleshooting charts vary,
depending upon the purpose of the equipment & the particular manufacturer.
The troubleshooting chart is broken down into the basic columns; Complaints,
Possible Cause & Repair.

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HERMETIC REFRIGERATION SYSTEM DIAGNOSIS

1. GENERAL
Each complaint is followed by probable causes and suggested repairs. To isolate the
possible cause, proceed in a systematic manner to determine the faulty component. This
guide does not cover all possible troubles and deficiencies that may occur under
conditions of operation.

2. ELECTRICAL CHECK:
A. Compressor Does Not Run-
1. Check power at outlet receptacle. Your compressor is designed to operate (see
serial no. and data plate) on 115-60-1 with a voltage range of 126.5 – 103.5. Your
240/220-50-1 will operate within range of 264-198.
2. Check thermostat for proper setting and continuity. Make sure control setting is
not in an “Off” position. Continuity may be verified by following instructions on the
individual compressor motor circuits.
3. Look for obvious loose or broken wiring.
4. Following systematically the instruction listed on the compressor motor circuitry,
check the relay, overload, and if employed, the start capacitor for continuity.
Replace any components found faulty with the recommended service parts.

3. TROUBLESHOOTING AND SERVICE CHART

COMPLAINT POSSIBLE CAUSE REPAIR
A. Compressor will not 1. Line disconnect switch 1. Close start or disconnect

start – no hum open. switch.
2. Fuse removed or blown 2. Replace fuse.
B. Compressor will not 3. Overload protector tripped 3. Refer to electrical diagram.
start – hums 4. Control stuck in open 4. Repair or replace control.

position. 5. Relocate control.
5. Control off due to cold
6. Check wiring against
location. diagram.
6. Wiring improper or loose.
1. Check wiring against
1. Improperly wired. diagram.

2. Low voltage to unit. 2. Determine reason and
correct.
3. Starting capacitor
defective. 3. Determine reason and
replace.
4. Relay failing to close.
4. Determine reason and
5. Compressor motor has correct, replace if
winding open or shorted. necessary.

6. Internal mechanical trouble 5. Replace compressor.
in compressor.
6. Replace compressor.

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COMPLAINT POSSIBLE CAUSE REPAIR
C. Compressor will not
1. Improperly wired 1. Check wiring against
start – hums but
trips on overload diagram.
protector.
2. Low voltage to unit. 2. Determine reason & correct.
D. Compressor starts
and runs, but short 3. Relay failing to open. 3. Determine reason & correct,
cycles on overload
projectors. replace if necessary.

E. Unit runs ok, but 4. Run capacitor defective. 4. Determine reason & replace
short cycles.
5. Excessively high discharge 5. Check discharge shutoff,

pressure. possible overcharge.

6. Compressor motor has a 6. Replace compressor.

winding open or shorted.

7. Internal mechanical trouble 7. Replace compressor.

in compressor (tight).

1. Additional current through 1. Check wiring diagram, check

overload protector. for added fan motors,

pumps, etc., connected to

wrong side of protector.

2. Low voltage to unit. 2. Determine reason and

correct.

3. Overload protector 3. Check current, replace

defective. protector.

4. Run capacitor defective. 4. Determine reason and

replace

5. Excessive discharge 5. Check ventilation, restriction

pressure. in cooling medium, restriction

in refrigeration system.

6. Check for possibility of

6. Suction pressure too high. misapplication, use stronger

unit
7. Compressor too hot – return 7. Check refrigerant charge (fix

gas hot. leak), add if necessary.

8. Compressor motor has a 8. Replace compressor.

winding shorted.

1. Overload protector 1. See D
2. Thermostat 2. Differential set too close –

3. High pressure cut-out due widen.

to:

a. Insufficient air. 3a. Check air to condenser
–correct.

b. Overcharge. 3b. Reduce refrigerant

charge.

c. Air in system 3c. Purge

4. Low pressure cut-out due to:

a. Undercharge 4a. Fix leak, add refrigerant.

b. Restriction in 4b. Replace device

expansion device.

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COMPLAINT POSSIBLE CAUSE REPAIR
F. Units operates long 1. Shortage of refrigerant. 1. Fix leak, add charge.
2. Control contacts stuck or 2. Clean contacts or replace
or continuously
frozen control.
G. Start capacitor open, 3. Refrigerated space has 3. Determine fault and correct.
shorted or blown
excessive load or poor 4. Replace with larger system.
H. Relay defective or insulation
burned out 4. System inadequate to 5. Defrost.
handle load. 6. Determine location and
I. Space temperature 5. Evaporator coil iced.
too high 6. Restriction in refrigeration remove.
system. 7. Clean condenser.
J. Suction line frosted 7. Dirty condenser. 8. Clean or replace.
or sweating. 8. Filter dirty 1. Check and replace.
1. Relay contacts not operating
K. Liquid line frosted or properly 2a. Determine reason and
sweating 2. prolonged operation on start correct.
cycle due to:
L. Unit noisy a. low voltage to unit 2b. Replace.
b. Improper relay 2c. Correct by using pump
c. Starting load too high
down arrangement if
3. Excessive short cycling necessary
3. Determine reason for short
4. Improper capacitor. cycling (E above) & correct.
4. Determine correct size and
1. Incorrect relay replace.
2. Incorrect mounting angle 1. Check and replace.
2. Remount relay in correct
3. Line voltage too high or too position.
low 3. Determine reason and
correct.
4. excessive short cycling 4. Determine reason (see E)
and correct.
5. Relay being influenced by 5. Remount rigidly.
loose vibrating.
6. Replace with proper
6. Incorrect run capacitor capacitor.

1. Control setting too high. 1. Reset control.
2. Inadequate air circulation. 2. Improve air movement.
1. Evaporator fan not running. 1. Determine reason and

2. Overcharge of refrigerant. correct.
1. Restriction in dehydrator or 2. Correct charge.
1. Replace part.
strainer
1. Loose parts or mounting. 1. Find and tighten.
2. Tubing rattle 2. Reform to be free of contact.
3. Bent fan blade causing 3. Replace blade.
4. Replace motor.
vibration.
4. Fan motor bearings worn.

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TROUBLESHOOTING CHART

TROUBLE COMMON CAUSE REMEDY
1. Unit will not run
 Blown fuse  Replace fuse
2. Refrigerator section
too warm  Low voltage  Check outlet with voltmeter,

should check 115V plus or

minus 10 percent.

 If circuit overloaded, either

reduce load or have

electrician install separate

circuit.

 If unable to remedy any other

way, install auto transformer.

 Broken motor or temperature  Jumper across terminals of

control control. If unit runs and

connections are all tight,

 Broken relay. replace control.
 Broken overload.  Check relay, replace if

necessary.

 Broken compressor  Check overload, replace if

necessary.

 Check compressor, replace if

 Defective service cord. necessary.
 Check with test light at unit; if

no circuit and current is

indicated at outlet, replace or

repair.

 Broken lead to compressors,  Repair or replace broken

timer or cold control leads or cold control.

 Broken timer.  Check with test light and

replace if necessary.

 Repeated door openings  Instruct user.

 Overloading of shelves,  Instruct user.

blocking normal air

circulation in cabinet

 Warm or hot foods placed in  Instruct user to allow foods to

cabinet. cool to room temperature

before placing in cabinet.

 Poor door seal.  Level cabinet, adjust door

seal.

 Interior light stays on.  Check light switch; if faulty,

replace.

 Refrigerator section airflow  Turn control knob to colder

control. position. Check airflow

heater.

 Check if damper is opening

by removing grille. With door

open, damper should open. If

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TROUBLE COMMON CAUSE REMEDY

control inoperative, replace

control.

 Cold control knob set at too  Turn knob to colder position

warm a position, not

allowing unit to operate

often enough.

 Freezer section grille not  Reposition grille.

properly positioned.

 Freezer fan not running  Replace fan, fan switch, or

properly defective wiring.

 Defective intake valve.  Replace motor compressor.

 Air duct seal not properly  Check and reseal or put in

sealed or positioned. correct position.

3. Refrigerator section  Refrigerator section airflow  Turn control knob to warmer

control too cold knob turned to coldest position.

position.

 Airflow control remains  Remove obstruction.

open.

 Broken airflow control.  Replace control.

 Broken airflow heater.  Replace heater.

4. Freezer section and  Fan motor not running.  Check and replace fan motor

refrigerator section if necessary.

too warm.  Cold control set too warm or  Check and replace if

broken. necessary.

 Finned evaporator blocked  Check defrost heater

with Ice. thermostat or timer, either

one 0f these could cause this

condition.

 Shortage of refrigerant.  Check for leak, repair,

evacuate and recharge

system.

 Not enough air circulation  Relocate cabinet or provide

around cabinet. clearances to allow sufficient

 Dirty condenser or circulation.

obstructed condenser ducts.  Clean the condenser and

the ducts.

 Poor door seal  Level cabinet, adjust door

seal

 Too many door openings  Instruct customer.

5. Freezer section too  Cold control knob  Turn knob to warmer position

cold improperly set.

 Cold control capillary not  Tighten clamp or reposition.

properly clamped to

evaporator.

 Broken cold control  Check control. Replace if

necessary.

Chart lists some common hermetic system troubles. Their causes, and suggested remedies

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Installing and Servicing Small Hermetic Systems
TROUBLESHOOTING CHART

TROUBLE COMMON CAUSE REMEDY
6. Unit runs all the time  Not enough air circulation  Relocate cabinet or provide

7. Noisy operation around cabinet or air proper clearances around
circulation is restricted cabinet -remove restriction
8. Unit cycles on  Check and make necessary
overload  Poor door seal adjustments.
 Explain to customer that
 Freezing large quantities of heavy loading causes long
ice cubes or heavy loading running time.
after shopping  Undercharge or overcharge
-check, evacuate and
 Refrigerant charge. recharge with proper
charge.
 Room temperature too  Ventilate room as much as
warm. possible.
 Check control; if it allows
 Cold control. unit to operate all the time,
Check if light goes out,
 Defective light switch. replace control.
 Excessive door openings  Replace switch if necessary.
 .Loose flooring or floor not  Instruct customer
 Tighten flooring or brace
firm. floor.
 Tubing contacting cabinet-  Move tubing.

or other tubing  Level cabinet.
 Cabinet not level.  Move tray -place on styro
 Drip tray vibrating
foam pad if necessary.
 Fan hitting liner or  Move fan
mechanically grounding.
 Replace compressor
 Compressor mechanically mounts.
grounded
 Replace relay.
 Broken relay.  Replace overload protector.
 Weak overload protector.  Check outlet with voltmeter.

 Low voltage Underload voltage should
be 115V plus or minus 10
 Poor compressor percent. Check for several
appliances on same circuit
or extremely long or under-
sized extension cord being
used.
 Check with test cord and
also for ground before
replacing.

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TROUBLE COMMON CAUSE REMEDY
9. Stuck motor  Broken valve  Replace motor compressor.
 Insufficient oil.  Add oil; if unit still will not
compressor.
operate, replace motor
 Overheated compressor compressor.
 If compressor faulty for any
10. Frost or ice on  Broken timer. reason, replace motor
finned evaporator compressor.
 Defective defrost heater  Check with test light and
11. Ice in drip catcher  Defective thermostat replace if necessary.
 Defective drip catcher  Replace heater.
12. Unit runs all the  Replace thermostat.
time, temperature heater  Replace heater
normal  Ice builds up on the
 Check door gaskets -
13. Freezer runs all the evaporator replace if necessary.
time. Temperature  Control bulb on thermostat
too cold  Place control bulb in,
not in contact with the contact evaporator surface.
14. Freezer runs all the evaporator surface.
time. Temperature  Faulty thermostat.  Check thermostat -test and
too warm replace if necessary.
 Ice buildup in insulation
 Remove breaker strips, stop
15. Rapid ice buildup on  Leaky door gasket unit, melt ice and dry
the evaporator insulation, seal outer shell
leaks and joints and -,. then
16. Door on freezer  Faulty electric; gasket assemble.
compartment, heater.
freezes shut.  Adjust door hinges. Replace
 Faulty gasket seal. door gasket if cracked,
brittle or worn.
17. . Freezer works then  Moisture in refrigerator
warms up  Use alternate gasket heater
 Wax buildup in capillary or install new one.
18. Gradual reduction in tube
freezing capacity.  Inspect and check gasket. If
worn, cracked or hardened,
replace it.

 Install drier in liquid line

 Use capillary tube cleaning
tool or replace capillary
tube.

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DOMESTIC AND LIGHT COMMERCIAL SYSTEMS

The "Troubleshooting and Service Chart" is quite self-explanatory; however, a
discussion of some of the complaints, possible causes, and repair solutions may be of some
additional assistance.

COMPLAINT "A" is Compressor will not start. No hum. Possible causes are:

1. Switch open. Rather obvious, but maybe it would be wise to deter- mine why
or who opened it.

2. Fuse removed or blown. Again, was there a reason?
3. Overload protector tripped. Here, too, it is not a case of waiting until the

overload resets, but rather to determine why.
4. Control stuck in open position. Faulty contactors may be a cause, although

every effort is made to provide the best quality contactors. And heed this
warning: Don't use the insulated end of a screwdriver to hold the contactor in.
In doing so you run the risk of burning out a good compressor.

COMPLAINT "B" is Compressor will not start-hums and trips on overload.

1. & 2. have been discussed (see Complaint "A").
3. Starting capacitor defective. It says "determine reason." Possibly a start

capacitor was installed which had too Iowa voltage rating.
4. Relay failing to close. Is the correct one being used? There seems to be a

considerable tendency to substitute something other than the one specified-if it
works, leave it. We say, please don't do it.
5. Compressor has a winding open or shorted. The repair specified says simply
"replace compressor." This means if the cause indicated has been proved -
without doubt -conclusively -no question about it-only then replace the
compressor. Remember that replacing the compressor is generally the most
costly repair bill an owner can get. So be sure-first.
6. Internal mechanical trouble in compressor. If the serviceman has proved
without question that none of the other possible causes are the reason for the
condition, then and then only can it be mechanical trouble.

A "Troubleshooting Chart" of this kind is not the entire answer. There are probably a
number of other reasons for the cause of each "complaint" listed, so keep in mind that
application of knowledge gained through experience and common sense are as much a part
of troubleshooting as the use of any chart.

COMPLAINT "C" is Compressor starts but stays on run winding. How do you know
this condition is occurring? If the ampere stay higher than normal. Or if you don't hear
the changeover.

1. through 3. Covered previously (see Complaint "A" and "B").
4. Run capacitor defective. If the run capacitor is failed closed, there will be a

period of time when the current and running sounds will seem to indicate the
relay has not switched. In a relatively short period of time, the start winding will
burn, so time is of the essence in this case.
5. High head pressure. Be sure to check all the things listed in the "repair" column.

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COMPLAINT "D" is Compressor starts and runs, but short cycles on overload
protector.

1. Mentioned before (see Complaint "A").
2. Low voltage to unit (or unbalanced if three-phase). In the matter of three-phase

unbalance-this is an instance in which it is probably wise to call in the power
company, or check with the building owner to determine what other equipment
is on the source of power to cause the unbalance.
3. Overload protector defective. Sometimes difficult to determine. One good clue is
how it looks-does it show to have been overheated?
6. Suction pressure too high. This will occur more often on refrigeration than air
conditioning, especially on low temperature equipment.
7. Compressor hot-insufficient gas cooling. Usually a result of a low charge.

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Hermetic Compressor Service Chart

PROBLEMS AND CAUSES REMEDIES

Compressor will not start -no hum

1. Open line circuit. 1. Check wiring, fuses, and receptacle.

2. Protector opens. 2. Wait for reset -check current.

3. Control contacts open. 3. Check control, check pressures.

4. Open circuit in stator. 4. Replace stator or compressor.

Compressor will not start -hums intermittently (cycling on protector).

1. Improperly wired. 1. Check wiring against diagram.

2. Low line voltage. 2. Check main line voltage, determine

location of voltage drop.

3. Open starting capacitor. 3. Replace starting capacitor.

4. Relay contacts not closing. 4. Check by operating manually. Replace

relay if defective.

5. Open circuit in starting winding. 5. Check stator leads. If leads are all

right, replace compressor.

6. Stator winding grounded (normally will 6. Check stator leads. If leads are all

blow fuse). right, replace compressor.

7. High discharge pressure. 7. Eliminate cause of excessive

pressure. Make sure discharge shut-

off and receiver valves are open.

8. Tight compressor. 8. Check oil level -correct binding

condition, if possible. If not, replace

compressor.

9. Weak starting capacitor or one weak. 9. Replace.

capacitor of a set

Compressor starts, motor will not get off starting winding.

1. Low line voltage. 1. Bring up voltage.

2. Improperly wired. 2. Check wiring against diagram.

3. Defective relay 3. Check operation -replace relay if

defective.

4. Running capacitor shorted. 4. Check by disconnecting running

capacitor.

5. Starting and running windings shorted 5. Check resistances. Replace

compressor if defective.

6. Starting capacitor weak or one of a set 6. Check capacitance -replace if

open. defective.

7. High discharge pressure. 7. Check discharge shutoff valves.

Check pressure.

8. Tight compressor. 8. Check oil level. Check binding.

Replace compressor if necessary.

Compressor starts and runs but cycles on protector.

1. Low line voltage. 1. Bring up voltage.

2. Additional current passing through 2. Check for added fan motors and

protector. pumps connected to wrong side of

protector.

3. Suction pressure too high. 3. Check compressor for proper

application.

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PROBLEMS AND CAUSES REMEDIES
4. Discharge pressure too high. 4. Check ventilation, restrictions and

5. Protector weak. overcharge.
5. Check current -replace protector if
6. Running capacitor defective.
defective.
7. Stator partially shorted or grounded. 6. Check capacitance -replace if

8. Inadequate motor cooling. defective.
9. Compressor tight. 7. Check resistances; check for ground -

10. Unbalanced line (three phase). replace if defective.
8. Correct cooling system.
11. Discharge valve leaking or broken. 9. Check oil level. Check for binding
Starting capacitors burnout.
condition.
1. Short cycling. 10. Check voltage of each phase. If not

2. Prolonged operation on starting equal, correct condition of unbalance.
winding. 11. Replace valve plate.

3. Relay contacts sticking. 1. Reduce number of starts to 20 or less
4. Improper relay or incorrect relay per hour.

setting. 2. Reduce starting load (install
5. Improper capacitor. crankcase pressure limit valve),
increase voltage if low -replace relay if
6. Capacitor voltage rating too low. defective.

7. Capacitor terminals shorted by water. 3. Clean contacts or replace relay.
4. Replace relay.
Running capacitors burnout
1. Excessive line voltage. 5. Check parts list for proper capacitor
rating -mfd. and voltage.
2. High line voltage and light load.
6. Install capacitors with recommended
3. Capacitor voltage rating too low. voltage rating.

4. Capacitor terminals shorted by water. 7. Install capacitors so terminals will not
be wet
Relays burnout
1. Low line voltage. 1. Reduce line voltage to not over 10
percent above rating of motor
2. Excessive line voltage.
2. Reduce voltage if over 10 percent
3. Incorrect running capacitor. excessive.

4. Short cycling. 3. Install capacitors with recommended
voltage rating.

4. Install capacitors so terminals will not
be wet.

1. Increase voltage to not less than 10
percent under compressor motor
rating.

2. Reduce voltage to maximum of 10
percent above motor rating.

3. Replace running capacitor with correct
mfd. capacitance.

4. Reduce number of starts per hour.

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PROBLEMS AND CAUSES REMEDIES
5. Relay vibrating. 5. Mount relay rigidly.
6. Incorrect relay. 6. Use relay recommended for specific

motor compressor

Troubleshooting Guide

Basic System Requirements

 Electrical System
1. All electrical joints & connection must properly insulated & firm.
2. Equipment grounding connection must be firm & connected to earth.
3. Actual load current must not exceed to the nameplate current rating.
4. Actual voltage must play to the tolerance of  10% of the unit voltage
rating.
5. Wire size must be long enough to carry the load current.
6. All electrical components & parts must be in good condition before in
operation.

 Mechanical System
1. Sufficient liquid refrigerant in the evaporator.
2. Sufficient contact between the cool space & the evaporator.
3. Correct temperature & pressure in the condenser.
4. Properly size condenser.
5. Sufficient heat removal for the condenser.
6. Correct amount of refrigerant chart.
7. Free from leaks & moisture & properly evacuated.

Trouble Signals

A fault in any part of the refrigerating mechanism will usually show up as an
unsatisfactory temperature or operating condition of the refrigerator; such conditions may
include:

1. Refrigerator does not run.
2. Refrigerator runs all the time; temperatures are too cold.
3. Refrigerator runs all the time; temperatures are too warm.
4. Refrigerator runs all the time; temperatures are satisfactory.
5. Refrigerator cycles but food compartment is too warm; freezing

compartment is satisfactory.
6. Refrigerator cycles but freezing compartment is too cold.
7. Motor control cuts out.
8. Refrigerator cycles satisfactorily; refrigeration is poor. 9. Refrigerator

cycles; but does not freeze ice cubes.
9. Refrigerator cycles; too much ice accumulates on the evaporator.
10. Refrigerator mechanism is very noisy.

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Hermetic Troubleshooting / Servicing Guide

 To service refrigerating units successfully, one must know how they should
perform when in good condition.

 Always check the system data before trying to locate the cause of the trouble.
System data is usually located on the identification plate mounted at the
motor compressor. Nameplate data must have in mind before beginning any
service operation, as follows;

70 oF Ambient 90 oF Ambient 100 oF
Temperature Temperature Ambient

Cabinet Temperature 38 o 40 o 47 o
% Operating Time
Cycles per Hour 38 60 100
kWhr./24 hour 3 2 none
Control Position 3.8 6.0 9.9
Evaporator Air Temperature 4 4
Suction Pressure (min-max) 1.5 o -1o 4
Watts (complete system) 2 in Hg – 13mpsig 0 – 13 psig 0o
13 – 20 psig
390  20 395  20
395  20

Chart shows operating characteristics of 18 cu. ft. combination refrigerator – freezer
which has 1/3 hp, two poles motor compressor.

Note that kW hr. (average over 24 hr.) changes as ambient temperature changes.

DATA

Refrigerant R – 134-a
Charge (in Ounces) 10 ½
Compressor hp 1/3
Compressor Speed 3450
rpm 5.6
Running Amperes 120
Voltage single
Phase

Refrigerant and electrical data which is typical of

information found on identification plate mounted on motor compressor.

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Normal Operation of a Refrigeration/Aircon
1. Evaporator coil completely covered with frost (ice).If evaporator temperature below
freezing point of water (32 degree F)
2. Condenser coil temperature is normal (120-130 degree F)
3. Evaporator coil is completely sweating (34 degree F- 45 degree F (aircon)
4. Low side pressure is normal (standard pressure). Low side pressure.
a) Refrigerator 3-12 psig (R-134-a) f3t4-
b) Aircon -60 -80 psig (R-22)
5. High side pressure is normal.
a) Refrigerator-130 - 180 psig
b) Aircon-260 280 psig
6. Full load ampere is normal base on nameplate.
7. Evaporator temperature is normal.
a) Refrigerator- 0 degree F-5 degree F
b) Aircon-34 degree F -45degree F
8. A few minutes of operation, a sharp temperature drop felt in suction line.
9. Filter drier temperature is normal (125 degree F).
10. During off cycle (off compressor motor) pressure in .low side and high side are
equalized.

Common Troubles of Compressor Motor Connections

Compressor motor fails to start…
A) no humming.
1. No power
2. Open overload protector
3. Open running winding
4. Loose connections
5. Open coil of current relay
B). With humming.
1. Low voltage  10% of power supply
2. Shunted winding
3. Open starting winding
4. Grounded winding
5. Tight/stuck-up compressor
6. Defective starting capacitor
7. Defective running capacitor
8. Defective starting relay (open contact)
9. Loose connection
C) Start and run by cycles on Overload Protector.
1. Low voltage :f: 10% of power supply
2. Relay does not get-off starting winding
3. Weak overload protector
4. Additional current flowing in overload protector
5. Shunted winding
6. Tight compressor
7. Grounded windings
8. Defective capacitor

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Objectives: Job Sheet 1

Troubleshooting Refrigeration/Air conditioning
Unit

At the end of this practice, the learner/trainee should be able to:
o Troubleshoot refrigeration/air conditioning unit
o Rectify troubles found in a unit.
o apply safety practices in troubleshooting refrigeration/air
conditioning unit

1. After the Information Sheet 5: Plan and Prepare for Troubleshooting, you are task to
troubleshoot an actual unit.

2. You can use this Information Sheet as a guide while performing your task.

3. The purpose of this activity is to enhance your knowledge and skill in troubleshooting
and repair.

4. Your tasks are;
o Ask your trainer for a defective refrigeration/air conditioning unit.
o Gather tools, materials and equipment that are necessary to perform this
activity.
o Troubleshoot the unit.
o If you found the possible trouble/s, ask your instructor to check your work.
o Rectify the troubles found.
o After completion, let your trainer check your work.
o Perform housekeeping.

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Information Sheet 2

Hermetic Motor Compressor

Hermetic motor is a very common and considered as an important component in
refrigeration system. The design characteristic of motor depends on whether the unit starts
under load, no load, or a balance pressure condition. The torque is provided by a magnetic
force developed in the field winding. They induce strong current to the rotor and in return it
drives the compressor crankshaft and the connecting rod to allow the piston to move up and
down. A compressor is either piston or roller type with the electric motor fastened in it. It is
sealed and the whole unit is house in a dome.

The higher the starting torque (turning effort) needed for that unit that starts under
load requires the use of larger conductors in the starting circuit. Most manufacturers try to
provide starting power equal to twice the running power. That is a 1/8 hp motor is designed
to produce ½ hp during starting.

Hermetic motors are either single phase or polyphase. In this segment only single
phase induction hermetic motors are explained. The figure below illustrates the construction
of hermetic motor.

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Compressor Winding

Hermetic compressor has its squirrel cage rotor directly coupled to the compressor
shaft and its stator inside the refrigeration system. The refrigerant vapor and oil surround the
whole unit. The construction and internal connection is similar to a split phase motor. It
consist of two identical windings the start and run winding. The former is fine while the latter
is a bigger wire wound in a core.

The split phase motors obtained the stator torque by adding a second winding to the
stator. This is a start winding. The conductor used in this winding is smaller than the
conductors used in run winding. It has higher resistance. Its purpose is to obtain a phase
displacement between windings so that it provides enough starting torque to spin the rotor.

Each winding has its specific resistance. The starting winding measures 30 ohms
while the run winding measures 4.5 ohms. These two windings are connected. The point of
connection is the common terminal. The end of starting is starting terminal while the other
end of running is running terminal. Since the windings are connected at common terminal.
The resistance is higher when measured between running and starting terminal which is 34.5
ohms. It is the combined resistance of two windings connected in series.

Hermetic Compressor Terminal

To obtain a correct compressor connection the motor terminal must be identified
correctly to prevent the motor from burning when supplied by electricity. Generally,
identification of compressor terminals is based on their arrangement. These are arranged in
triangular arrangements. The upper position is the “common” terminal; the left side is the
“starting” terminal and “running” on the other side. The figure below specifies the
arrangement of terminals.

COMMON

START RUN

Be careful not to interchange the connection to avoid burning out of windings. It will
immediately burn out after supplying power. The run winding should be wired directly to line
and should stay the circuit to maintain the rotor rotation while the start winding is wired to a
capacitor to correct the power factor of the compressor while it is operating.

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If you are not certain, it is best to identify the terminal by testing the compressor
resistance. Just remember that the highest resistance is the combined resistance of starting
and running winding. The lowest resistance is the running winding while the joint wire of
running and starting winding is the common terminal, the other end of each winding should
be running and starting winding terminal.

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Self-Check 1

Hermetic Motor Compressor

Test what you have learned about hermetic compressor.

Fill in the Blanks
Direction: Complete the sentences below by filling the blanks with appropriate word/s.

1. Hermetic compressor is very common and considered as an important component
in _______________ system

2. A compressor is either __________ or __________ with electric motor fastened in
it.

3. It is sealed and the whole unit is housed in a __________.
4. Hermetic compressors are either _________ or _________.
5. The compressor winding is consist of two identical windings the _________ and

_________ winding.

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Hermetic Motor Compressor

1. refrigerating system
2. piston or roller type
3. dome
4. single phase or polyphase
5. starting and running

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Assignment Sheet 1

Identifying Hermetic Compressor Terminal

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

o Analyze the resistances of each terminal.
o Identify the terminals with the given resistances.

Procedures:

1. The table shown below is an obtained test result of a 1.5 hp compressor, it reveals
that the resistances are;

Terminals Resistance
12 3.5 ohms
13 1.5 ohms
23 5 ohms

2. Identify among the three which is the common, start and run winding terminals
based on the given data in the table.

3. Upon completion, check your work with the answer key provided at the back of this
module.

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Self-Check 2

Identifying Hermetic Compressor Terminal

1. The table shown below is an obtained test result of a 1.5 hp compressor, it reveals
that the resistances are;

Terminals Resistance
12 3.5 ohms
13 1.5 ohms
23 5 ohms

2. From the table terminal 2 and 3 is the highest resistance either of this terminal is start
or run, therefore terminal 1 is COMMON.

3. Terminal 1 and 3 is the lowest resistance, this indicates that this is the run winding.
Since terminal 1 is already pin pointed as COMMON terminal, therefore terminal 3 is
RUN terminal.

4. The configuration of terminals therefore are as follows:

COMMON
1

2 3

START RUN

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Operation Sheet 1

Determining Hermetic Compressor Motor Terminal
Using Multimeter

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

o Tag the three terminal using number or letter.
o Obtain resistance results from the three terminals of compressor
o Identify the terminals.

Equipment: - 1 unit
o Multi meter 1 unit
o Compressor
- 1 pc
Materials: 1 pc
o Rag 1 pc
o sand paper
o pencil/ball pen - 1 pc
o masking tape 1 pc
1 pc
Tools: 1 pc
o Phillips screw driver
o Flat screw driver - 1 pair
o Long nose pliers - 1 pc
o Diagonal cutting pliers

Personal Protective Equipment:
o Gloves
o Goggles

Procedures:

1. Ask your instructor for 1 unit hermetic compressor.
2. Obtain the necessary tools materials and equipment.
3. Take the necessary data to identify the terminals of motor.
4. Upon completion, ask your instructor to check your work.
5. Perform housekeeping

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