ITI/NCVT RAC Mechanic (AITT Theory) study plan

Sketch and label a complete vapour compression cycle from memory, marking pressure and enthalpy at all four state points

Explain the function of each of the four core components and trace refrigerant flow direction on your sketch

Define sensible heat, latent heat, saturation temperature and superheat, and calculate superheat from given gauge and thermometer readings

Convert between gauge and absolute pressure and between Celsius, Fahrenheit and Kelvin in 20 practice calculations

State the relationship between evaporating pressure, condensing pressure and compression ratio for three sample systems

Describe the construction and working of reciprocating, rotary and scroll compressors and match each type to its typical application

Compare air-cooled and water-cooled condensers and list the maintenance points of each

Distinguish natural draught, forced draught and dry expansion evaporators and state where each is used

Explain the operation of capillary tube, thermostatic expansion valve, automatic expansion valve and electronic expansion valve

Calculate the effect of incorrect superheat setting on evaporator performance and compressor suction temperature

Classify refrigerants by ASHRAE safety group and state the flammability and toxicity rating of the common working fluids used in domestic and commercial equipment

Explain ozone depletion potential and global warming potential and describe the phase-out obligations that apply to HCFC and HFC refrigerants

List the safe handling, cylinder storage, charging and recovery procedures for refrigerant and lubricant, including the hazards of mixing oils

Identify the correct lubricant family for mineral oil, POE and PAG systems and explain moisture sensitivity of POE

Apply Ohm's law and series and parallel circuit rules to calculate current, voltage and resistance in control circuits

Describe how a multimeter, clamp meter, megger and series-parallel testing are used to check a circuit safely

Select and use the correct hand tool for tube cutting, flaring, swaging, bending and brazing, and state the safety check before each operation

Read a vernier calliper, micrometer and manifold gauge set to the correct least count in 20 practice readings

Demonstrate leak testing with nitrogen pressure and soap solution and state the pressure limits for each test stage

Draw the wiring diagram of a domestic refrigerator including thermostat, overload protector, PTC or relay start and light circuit

Explain the function of the starting relay, overload protector, thermostat, capacitor and defrost timer in a control circuit

Describe the input and output signals of a refrigerator PCB and the checks used to confirm a faulty board

Trace the refrigerant and air paths of a domestic refrigerator, deep freezer, water cooler, bottle cooler and visi cooler and state the typical operating temperature range of each

Explain the defrost systems used in frost-free refrigerators and the faults that cause excessive frost or no cooling

Diagnose five common complaints, including no cooling, continuous running, short cycling and water leakage, by listing the probable cause and the test for each

Write a commissioning checklist covering evacuation, charging by weight, leak test, current draw and pull-down time

Prepare a preventive maintenance schedule for a commercial visi cooler covering condenser cleaning, gasket inspection, drain line and electrical checks

Compare window, split, cassette, ductable, package and central plant systems by capacity range, installation method and typical application

Explain the refrigeration cycle and air distribution path of a ductable and a central chilled water plant

Read a psychrometric chart to find dry bulb, wet bulb, dew point, relative humidity, enthalpy and specific volume for five given air conditions

Calculate sensible heat ratio and apparatus dew point for a simple room cooling load

Describe the installation sequence for a split air conditioner including bracket fixing, flare connections, vacuuming and gas charging

Perform a systematic fault-finding sequence on a refrigeration system using gauge readings, suction and discharge temperatures, current draw and visual inspection

Interpret abnormal gauge readings such as low suction, high discharge, fluctuating pressure and partial vacuum to identify restriction, undercharge, overcharge or air ingress

Explain the procedure for locating and repairing a leak, replacing a filter drier and recharging the system

Describe the correct method of component replacement for a compressor, condenser fan motor and expansion valve, including evacuation before recharging

List the safety precautions for brazing, pressure testing and refrigerant recovery during service work

Explain the construction and starting method of capacitor-start, capacitor-run and permanent split capacitor motors used in refrigeration and air conditioning

Describe the operation of a direct-on-line starter, thermal overload relay and contactor, and state the protection each provides

Trace a split air conditioner wiring diagram from supply through MCB, contactor, PCB, thermostat and fan and compressor motors

Test a capacitor, relay and motor winding with a multimeter and megger and interpret the readings

Revise all ten domains using a timed mock test and list weak areas for final review