Course Outline

Fundamentals of Automotive HVAC Systems Training Outline

Course Title: Fundamentals of Automotive HVAC Systems

Duration: 2 Weeks (Monday – Friday).

“Automobile Heating, Ventilation, and Air Conditioning (HVAC)”. This outline balances theory with essential hands-on practice.

Target Audience: Aspiring or current auto technicians, mechanics seeking specialisation, or technical students.

Week 1: HVAC Principles, Components, and Basic Operation

  • Day 1: Introduction, Safety, and Heating System Fundamentals
    • Morning (Theory):
      • Course overview and objectives.
      • Safety First: HVAC system pressures, refrigerant handling (R-134a, R-1234yf), chemical safety (oils, flush), electrical safety, proper use of Personal Protective Equipment (PPE – especially eye protection).
      • Basic principles of heat transfer (Conduction, Convection, Radiation).
      • Purpose of the automotive heating system.
      • Components: Heater core, heater control valve (if applicable), hoses, thermostat’s role.
  • How engine coolant temperature affects heating.

Afternoon (Practical):

  • Identifying heating system components on training vehicles/benches.
  • Demonstration of safe handling procedures.
  • Inspecting hoses and heater core connections for leaks.
  • Basic thermostat testing concepts.
  • Day 2: Ventilation System and Airflow Control
    • Morning (Theory):
      • Purpose of the ventilation system (fresh air vs. recirculation).
      • Components: Blower motor and fan, resistor block/module, cabin air filter, air ducts, mode doors, blend doors.
      • How airflow is directed (Defrost, Vent, Floor modes).
      • How temperature is controlled (mixing hot and cold air using the blend door).
      • Manual vs. Electronic controls (basic overview).
    • Afternoon (Practical):
      • Locating ventilation system components.
      • Inspecting and replacing a cabin air filter.
      • Testing blower motor operation at different speeds.
      • Testing blower motor resistor (manual systems).
      • Observing mode and blend door actuation (manual controls).
  • Day 3: Introduction to Air Conditioning Principles & Refrigeration Cycle
    • Morning (Theory):
      • Purpose of the AC system (cooling and dehumidification).
      • Basic Thermodynamics: States of matter, heat absorption during evaporation, heat release during condensation, pressure-temperature relationship.
      • The Refrigeration Cycle: Explanation of the four main stages: Compression, Condensation, Expansion, Evaporation.
      • Role of refrigerant as the heat transfer medium.
    • Afternoon (Practical/Demo):
      • Using Pressure-Temperature charts for R-134a.
      • Demonstration of evaporation causing cooling (e.g., alcohol swab).
      • Tracing the basic flow of refrigerant on diagrams and training units.
  • Day 4: AC System Components (High Side)
    • Morning (Theory):
      • Compressor: Types (fixed displacement, variable displacement), function (pressurizing refrigerant vapor), clutch operation.
      • Condenser: Function (rejecting heat, changing vapor to liquid), location, airflow importance.
      • Receiver/Drier (TXV Systems): Function (storing refrigerant, removing moisture/debris).
      • High-pressure lines.
    • Afternoon (Practical):
      • Identifying compressors, condensers, receiver/driers on vehicles.
      • Inspecting condenser fins for damage/blockage.
      • Demonstrating compressor clutch engagement/disengagement.
      • Locating high-side service port.
  • Day 5: AC System Components (Low Side) & Refrigerants/Oils
    • Morning (Theory):
      • Expansion Device: Function (metering refrigerant flow, pressure drop), Types (Thermal Expansion Valve – TXV vs. Orifice Tube – OT).
      • Evaporator: Function (absorbing heat from cabin air, changing liquid to vapor), location, condensate drain.
      • Accumulator (Orifice Tube Systems): Function (storing refrigerant, removing moisture, preventing liquid slugging).
      • Low-pressure lines.
      • Refrigerants: R-134a vs. R-1234yf (properties, environmental impact, safety).
      • Refrigerant Oils: PAG vs. POE, viscosity, importance of using the correct type and amount.
    • Afternoon (Practical):
      • Identifying evaporators (location basics), expansion valves/orifice tubes, accumulators.
      • Locating low-side service port.
      • Demonstrating different refrigerant cylinders and oil types.
      • Discussing oil balancing during component replacement.

Week 2: Diagnostics, Service Procedures, and Climate Control

  • Day 6: HVAC Electrical Controls & Basic Diagnostics
    • Morning (Theory):
      • Review of basic electrical circuits.
      • HVAC Control Panel inputs and outputs.
      • Compressor clutch control circuit.
      • Radiator/Condenser fan control circuits.
      • Pressure Switches/Sensors (High, Low, Binary, Trinary): Function and role in system protection and control.
      • Introduction to systematic diagnostics: Verify complaint, visual inspection, basic checks.
    • Afternoon (Practical):
      • Reading basic HVAC wiring diagrams.
      • Testing pressure switches (continuity checks).
      • Testing compressor clutch coil resistance and applying power (safely).
      • Using a multimeter to check fan motor circuits.
      • Introduction to Manifold Gauge Set: Connection and safety.
  • Day 7: AC System Performance Testing & Leak Detection
    • Morning (Theory):
      • Connecting Manifold Gauges: Procedures and safety.
      • Reading Static vs. Operating Pressures (High and Low Side).
      • Factors affecting pressures (ambient temp, engine RPM, airflow).
      • Interpreting pressure readings for common issues (low charge, overcharge, restrictions, air in system).
      • Using thermometers to check vent temperature and condenser/evaporator temperature differential.
      • Common causes of refrigerant leaks.
    • Afternoon (Practical):
      • Connecting manifold gauges to vehicles.
      • Recording static and operating pressures under various conditions.
      • Measuring vent temperatures.
      • Leak Detection Methods: UV Dye and light, Electronic Leak Detectors, Soapy water (basics), Nitrogen pressure testing concepts.
      • Hands-on practice with UV light and electronic leak detectors.
  • Day 8: AC Service Equipment and Procedures
    • Morning (Theory):
      • Recovery/Recycle/Recharge (RRR) Machine: Purpose and functions.
      • Refrigerant Recovery: Environmental regulations, importance of not venting.
      • System Evacuation (Vacuum): Purpose (removing air and moisture), procedure, importance of deep vacuum, vacuum decay testing.
      • Recharging the System: Methods (by weight vs. by pressure/volume – weight is preferred), adding refrigerant oil.
    • Afternoon (Practical/Demo):
      • Demonstration and supervised practice using an RRR machine:
        • Connecting hoses.
        • Performing refrigerant recovery.
        • Performing system evacuation (pulling a vacuum).
        • Recharging a system by weight.
  • Day 9: Automatic Temperature Control (ATC) Systems
    • Morning (Theory):
      • Difference between Manual HVAC and ATC.
      • ATC Components: Control module, interior/exterior temperature sensors, sunload sensor, humidity sensor, blend/mode door actuators (motors), aspirator motors.
      • How ATC maintains desired temperature automatically.
      • Basic ATC diagnostics: Self-diagnostics codes, using a scan tool to view sensor data and command actuators.
    • Afternoon (Practical/Demo):
      • Identifying ATC-specific sensors and actuators on vehicles.
      • Demonstration of using a scan tool to access the HVAC module.
      • Viewing ATC sensor data stream.
      • Performing actuator tests using a scan tool (if available).
  • Day 10: Common HVAC Problems, Troubleshooting Scenarios & Review
    • Morning (Theory):
      • Troubleshooting common complaints:
        • AC not cooling / blowing warm air.
        • Poor airflow from vents.
        • Noise from AC system (compressor, blower).
        • Intermittent cooling.
        • Water leaking into the cabin.
      • Integrating diagnostic steps: Combining visual checks, pressure readings, temperature measurements, leak detection, and electrical tests.
    • Afternoon (Review & Assessment):
      • Practical troubleshooting scenarios on training vehicles/benches.
      • Q&A session covering all topics.
      • Brief written or practical skills assessment.
      • Course feedback and closing.