Certified Refrigeration and Air-conditioning Technician Level-IV

How It Works

  1. 1. Select Certification & Register
  2. 2. Receive a.) Online e Learning Access (LMS)    b.) Hard copy - study material
  3. 3. Take exam online anywhere, anytime
  4. 4. Get certified & Increase Employability

Test Details

  • Duration: 60 minutes
  • No. of questions: 50
  • Maximum marks: 50, Passing marks: 25 (50%).
  • There is NO negative marking in this module.
  • Online exam.

Benefits of Certification

$49.00 /-

Vskills has developed a new strategic framework for Skill Development for early school leavers and existing workers, especially in the unorganized sector to improve their employability called Trade Employable Skills (TES).

Trade Employable Skills does effective assessment and certification of candidates in different trade disciplines like Electrical, Electronics, Agriculture, Chemical, Automobile, IT, etc to make them job ready.

Note: Please note that the course comes with online e-learning only. No hard copy will be provided.

Why should one take this certification?

To demonstrate clear understanding and practical aspects and to get a visible recognition for this knowledge.

Table of Content


Practice Test


Companies that hire Refrigeration and Air-conditioning Technician Level-IV

All small and medium companies need certified employees who have the requisite skills. There are more jobs opening up in the economy on a regular basis with the fast growth of the country.

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Constructional details and application of pumps

  • Construction of centrifugal pump
  • Purpose of each part is as follows
  • Types of pumps and usage
  • Centrifugal pumps
  • Reciprocating pumps

Details of centrifugal pump

  • Working of centrifugal pump
  • Calculation of head
  • Frictional losses 
  • Selection of pump

Functions and applications of water valves

  • Purpose of water regulating valve
  • Types and functions of regulating valves
  • Electrically operated
  • Actuated by pressure
  • Thermostatic
  • Adjusting pressure regulating valve
  • Capacity and efficiency of the condenser
  • The ratio of heat rejection factor is
  • Heat absorbed by the refrigerant in the evaporator
  • Water line vales and their function s
  • Globe valve
  • Gate valve
  • Ball valve
  • Butterfly valve
  • Check valve
  • Lift check valve
  • Swing check valve
  • Iron flanged check valve
  • Function of the check valve

Fault diagnosis in water circulating pumps

  • Air in the suction line
  • What is NPSH ?
  • Vibration in pump

Package Air – conditioners

  • Safety controls
  • The function of components
  • Compressor
  • Condenser
  • Expansion
  • Evaporator
  • Blower
  • High pressure cut out
  • Low pressure cut out
  • Overload relay
  • Thermostat
  • Water flow switch
  • Air filter

Construction details of package A/C

  • Construction of package A/C
  • Air distribution systems
  • Heat load calculation
  • Dry bulb temperature
  • Wet bulb temperature
  • Relative humidity
  • Dew point
  • Grains of moisture
  • Heat load calculation
  • Heat conversion

Safety switches and controls used in package A/C

  • Water pressure cutout switch
  • Electrical overload (over current protector)
  • Refrigerant flaw control(thermostatic expansion valve)
  • Installation
  • Working
  • Adjustment

Duct system of package A/C

  • Duct work details
  • Proper care for duct for duct system
  • Air distribution

Package A/C faults and diagnosis

  • Problem tree (LP cutout)

Automobile air – conditioning

  • Automobile airconditioning
  • Basic components
  • Compressor
  • Purpose
  • details
  • condenser
  • purpose
  • details
  • receivers/dryers and accumulators
  • purpose
  • receiver/dryer
  • accumulator
  • thermostatic expansion valve/orifice tube
  • purpose
  • evaporators
  • purpose
  • details
  • basic control
  • control
  • compressor operating controls
  • ambient temperature switch
  • thermostatic switch
  • Low pressure cut off switch
  • High pressure cut off switch
  • High pressure relief valve
  • Pressure sensing (cycling) switch
  • Thermal limiter and superheat switch
  • Service tip
  • Evaporator controls
  • Pilot operated absolute valve(POA)
  • Valves in receiver
  • Evaporator pressure regulator (EPR)Valve
  • Evaporator temperature regulator valve(ETR)
  • Fan controls
  • Cooling fan temperature switch
  • High pressure fan switch
  • A/C ‘on’ fan switch
  • A/c fan control switch
  • Driveability compressor controls
  • Constant run relay
  • Time delay relay
  • Wide open throttle cut off switch
  • Low vacuum switch
  • Power brake time relay
  • Power steering pressure cut off switch
  • High coolant temperature switch(HCTS)
  • Anti dieseling relay
  • Safety precautions
  • AIR BAGS (supplementary restraints system SRS)
  • Electrical
  • Refrigerant circuit
  • Safe handling of refrigerant containers
  • Caution
  • Swash plate axial type compressor

Different controls of CAR A/C

  • Installation of car A/C
  • Belts used in A/C
  • Condenser
  • Evaporator
  • Expansion valve
  • Ducts
  • Fans
  • Electrical
  • Thermostatic switch
  • Battery
  • Blower motor
  • Blower switch
  • Thermostat
  • Electromagnetic clutch
  • HP switch
  • LP-switch
  • Writing circuit
  • Pressure operated hot gas BPv

Performance of auto a/c system and troubleshooting

  • Performance test

Vapor absorptions system

  • Vacuum
  • Principle
  • Introduction of refrigerator
  • Two step

Domestic absorption system

  • Function of continuous absorption type of refrigerators
  • Automatic defrosting

Air refrigeration

  • Air refrigeration for  Aircrafts
  • Simple Cooling system
  • Ice Manufacturing

Ejector refrigeration

Non conventional refrigeration

  • Thermoelectric refrigeration process

Introduction to central Air- conditioning system

  • Calculate heat load
  • Wall gain load
  • Air change load
  • Product load
  • Occupancy load
  • Equipment load
  • Definition of Air-conditioning
  • Refrigerating Piping

Central air-conditioning plant wiring circuit

  • Motor control equipment
  • Protective devices
  • Fuses
  • Thermal overloads
  • Control sequence
  • Interlocking circuit
  • Control Relay

Compressors lub oil circulation

  • Piston and connecting rod assembly
  • Shaft seal
  • Bellow type shaft seal
  • Diaphragm type seal
  • Servicing lubrication oil pump
  • Splash Method
  • Forced feed
  • Oil Separator
  • Suction valve lifting arrangements in compressor
  • Hot gas bypass method- Capacity control
  • Cylinder bypass method- capacity control
  • Whirl vein capacity for centrifugal compressor

Efficiency testing of compressor

  • Efficiency of a compressor
  • Mechanical efficiency
  • Compression ratio
  • Volumetric efficiency
  • Performance factor
  • Break horse power
  • Reciprocating Compressor as Vacuum pump
  • Checking of external drive compressor
  • Compressor testing methods
  • Types of Reciprocating compressor
  • According to the cylinder
  • According to the working
  • According to the method of compression of the gas
  • According to the number of times of compression of gas
  • According to the cooling the head of the compressor
  • Safety precautions

Water flow differential pressure in shell and tube condenser

  • Quantity of water required per ton of refrigeration in shell and tube water cooled condenser.
  • Condenser capacity
  • Calculation
  • Parts of a shell and tube water cooled condenser
  • Function of a shell and tube condenser

De-scaling in shell and tube condenser

  • Necessity of descaling
  • Method of descaling
  • De-scale the condenser tube side(inner)

Chilled water storage tank, pipes and insulation

  • Chilled water tank and lines
  • Purpose of insulation for chilled water
  • The types and methods of insulations

Fans and Blowers of AHU, FCU and Air washer

  • Use of Fans and Blowers
  • Types of Fans-Blowers in Air conditioning plant
  • Forward curved fans
  • Backward curved fans
  • Backward inclined fans
  • Radial blade fans
  • Belt tensions of the belt driven
  • Drive methods employed  in fan operation
  • Selection of Blower fan

Safety devices of compressor

  • High pressure safety cut-out
  • High pressure cut-out and functions
  • Types of pressure controller
  • Bellow type
  • Diaphragm type
  • Bourdon tube type
  • Range and differential of a pressure switch
  • Differential pressure controller
  • Use of safety valve of relied valve
  • Fusable plug
  • Oil pressure safety switch use

Seasonal shut-down, maintenance of central Air-conditioning plant

  • Important checks and starting procedures
  • Post start- up checks
  • Log sheets
  • Starting procedures
  • Daily
  • Weekly
  • Monthly
  • Quarterly
  • Yearly
  • Operating plant at design efficiency

Vacuumising and gas charging in central air-conditioning plant

  • Objectives
  • Describe the vacuum sing of the plant
  • Explain about charging to the system
  • Describe the final testing of efficiency and other maintenance
  • Vacuumising of the plant
  • Charging gas to the system
  • Testing efficiency and other maintenance

Cooling towers

  • Name the parts of a cooling tower fan gear box drive shaft and motor and explain the function
  • Describe the use of cooling tower fan and its arrangement
  • Name of the part
  • Function
  • Servicing of motor and electrical connections
  • Assembly process of cooling tower fan
  • Cooling water process
  • Cooling pond
  • Cooling towers
  • Open tower
  • Close tower
  • Spray cooling ponds
  • Natural draft cooling towers
  • Mechanical draft cooling towers
  • Forced draft cooling tower
  • Induced draft cooling tower
  • Algae
  • Limitations
  • Range
  • Approach
  • Drift loss
  • Evaporation loss
  • Blow down
  • Make up water
  • Efficiency
  • Fan guard
  • Pine wood-hand rail
  • Fan cylinder
  • Inlet tee
  • Air inlet
  • Ladder
  • Asbestos casing
  • Inspection door
  • Series grid fills
  • Asbestos cement louvers
  • Nozzles
  • Distribution box

Central A/C Duct systems

  • Objectives
  • Duct materials standards;symbols,joints
  • Duct drawing symbols
  • Duct joints/symbols
  • Two seam lock methods
  • Ducts grilles and diffusers
  • Ducts
  • Diffusers and grilles
  • Return air
  • Duct joints
  • Electrode humidifiers
  • Water atomising humidifiers
  • Necessity of de-scaling in chilled water coils
  • De-scaling inAHU & Air-Washers
  • The Arrangement of AHU in Air-conditioning plant
  • Fan Coil Units
  • Air-washer’s applications in Air-conditioning plant

Air-Distribution Balancing in Ducts at Air-conditioning plants

  • Statics pressure and air velocity
  • Air distribution – balancing in ducts
  • Duck works
  • Duck insulations
  • Diffusers & Grilles
  • Reading the Mechanical drawings
  • Common faults and remedies
  • Safety requirement of duct system

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