NIMI Refrigeration and Air Conditioning Technician

Refrigeration & Air Conditioning Technician - 2nd Year

The second year is where basic knowledge turns into real technical skill. In the first year, you learned the fundamentals of cooling systems. In the second year, you will learn practical industry skills, advanced servicing methods, and real troubleshooting techniques.

If you're an ITI student preparing for your future in the refrigeration and air conditioning technician trade, or a working professional eager to upgrade your skills, then the NIMI Refrigeration and Air Conditioning Technician Trade Book is your ultimate companion.

Watch and Learn with NIMI!

Want to see the Refrigeration & Air Conditioning Technician 2nd Year Trade Practical Book in action before diving into the book? Head over to the official NIMI Digital YouTube Channel (@NIMIDIGITALENGLISH) and explore the Refrigeration & Air Conditioning Trade playlist.

Inside the Book: A Module-by-Module Breakdown

Module 1: Commercial Compressor

Think of the compressor as the heart of any refrigeration system. This module introduces you to different types of compressors, how they work, and how to maintain them. You'll learn:

• Familiarization with commercial reciprocating compressor and centrifugal compressor
• Dismantle and check compressor and accessories
• Check and service valve plate and piston assembly
• Check and test lubrication system
• Cutting gaskets
• Assemble compressor and test overall efficiency
• Connect star and delta connection on a three phase motor
• Start the motor through star - delta starter and measure starting current, running current and show changing of DOR
• Start the slip-ring induction motor through rotor resistance starter and measure starting current, running current and show changing of DOR

If the compressor stops, the whole system stops — that’s why learning it is crucial. Master this module and you become the technician everyone depends on.

Module 2: Water Cooled Condenser with Cooling Tower

From offices to hospitals, water coolers are everywhere. This module covers:

• Service water cooled condenser and receiver
• Test performance of water cooled condenser, inlet and outlet pressure and temperature
• Pump down the gas for necessary servicing and repair

If the condenser can’t release heat, cooling will never happen. This module teaches you how to keep the condenser performing at its best.

Module 3: Expansion Valve

If the compressor is the heart of the system, then the expansion valve is its control system deciding exactly how much refrigerant should enter the evaporator. You'll learn:

• Familiarize with thermostatic and electronic expansion valves
• Identify automatic expansion valve

Mastering expansion valves means you learn how to balance the system, and a well-balanced system always runs cooler, smoother, and more efficiently.

Module 4: Evaporators & Chillers

Once the refrigerant reaches the evaporator, the real magic happens — heat is absorbed, and cooling begins. You'll learn:

• Identify extended surface forced air cooled evaporators
• Service air cooled evaporator by blower
• Removing oil from coil

Mastering this module helps you understand where cooling is actually produced and how to keep both evaporators and chillers delivering peak performance every time.

Module 5: Coolers & Freezers

From bottle coolers in shops to deep freezers in restaurants, this module takes you through the systems that keep food, beverages, and perishables safe. You’ll learn:

• Install gauge manifold, leak test and refrigerant charging after evacuation
• Installation, servicing, maintenance and retrofit of water cooler/water dispenser
• Check and service bottle cooler and visible cooler

Coolers and freezers run 24/7, so even a small fault can lead to major losses. Understanding insulation, cabinet temperature control, frost formation, defrost cycles, and refrigerant balance helps you diagnose problems faster.

Module 6: Applications of Commercial Refrigeration

Commercial refrigeration is the backbone of hotels, supermarkets, cold rooms, dairy plants, and food processing units. You’ll learn:

• Identify parts, accessories, controls and operation of walk-in cooler/reach-in cabinet
• Preventive maintenance, troubleshooting and servicing of components
• Evacuate cold storage by two-stage vacuum pump and gas charging

Learning this module prepares you for high-value job roles because industries rely on skilled technicians who understand capacity, load management, temperature zoning, and system reliability.

Module 7: HVAC Systems

HVAC (Heating, Ventilation & Air Conditioning) is the modern standard for comfort cooling in offices, malls, hospitals, and high-rise buildings. You'll learn:

• Measuring air flow using anemometer
• Identify DBT, WBT, RH & other properties using psychrometric chart

HVAC is not just cooling — it’s comfort, air quality, and energy efficiency. Technicians who understand airflow, psychrometry, duct balancing, and ventilation control are in high demand in building management and facility operations. By mastering this module, you step into the world of smart buildings and large-scale cooling networks.

Module 8: Central & Industrial Air Conditioning

This module takes you deeper into large industrial cooling systems — central AC plants, cooling towers, pump systems, chilled water networks, and industrial refrigeration setups. You'll learn:

• Identify various components of package A/C (with air cooled condenser)
• Identify various components of package air conditioner with water-cooled condenser
• Identify various components of split package A/C
• Electrical circuit of split package AC
• Check air flow, dampers, temperature and pressure

Central AC systems involve multiple components working together — compressors, pumps, cooling towers, chillers, AHUs, and automation controls.

Module 9: Mobile Air Conditioning

This module explores air conditioning systems used in cars, buses, trucks, and other vehicles. You'll learn:

• Testing of system components & fault finding
• Leak testing using dry nitrogen, evacuation, gas charging, oil charging (HFC-134a, HFO-1234yf, and blends of HFCs and HFOs)

Vehicle AC systems face vibration, dust, heat, and load variations every second, making them one of the most challenging systems to maintain. Mastering this module helps you work confidently in automobile workshops, AC service centers, and transport fleets, where mobile cooling is a critical need.

Module 10: Study & Execute Commercial Plant Maintenance

This final module focuses on real industry maintenance practices. You'll learn:

• Study/execute repair of different commercial units at site
• Study/execute preventive maintenance of different commercial units at site

It’s the final step that turns you from a student into a job-ready refrigeration and air conditioning technician.

Learning Outcomes

By the end of the NIMI Refrigeration and Air Conditioning Technician Trade 2nd Year course, you will be able to:

• Service and repair commercial compressors, condensers, evaporators, and chillers
• Maintain and troubleshoot water coolers, dispensers, deep freezers, and cold storage units
• Install, service, and gas-charge package AC, split AC, ductable units, and VRF/VRV systems
• Read psychrometric charts and measure DBT, WBT, RH, and air flow
• Construct and insulate air ducts, and service motors, blowers, and filters
• Perform servicing and fault diagnosis of central AC plants, DX systems, chillers, and cooling towers
• Service and troubleshoot car AC and mobile AC systems
• Carry out preventive maintenance and maintain logbooks for commercial plants

These outcomes prepare you for real-world jobs in HVAC, refrigeration service companies, commercial plants, and industrial AC maintenance.