HVAC, Hybrid Vehicles & Restraint Systems
Automotive A/C components, refrigerants, heater core, HVAC controls, hybrid/EV high voltage safety, regenerative braking, airbags, and supplemental restraint systems.
- Explain automotive A/C system operation and refrigerant handling requirements
- Describe heater core, blower motor, and HVAC control functions
- Explain CAN bus vehicle network communication
- Identify hybrid and EV high-voltage safety procedures and components
- Describe airbag and supplemental restraint system operation and service precautions
Leçon 1
A/C System Components & Refrigerant Types
How Automotive A/C Works
The automotive air conditioning system removes heat and humidity from the passenger cabin using the refrigeration cycle. Refrigerant changes state between liquid and gas, absorbing heat when it evaporates and releasing heat when it condenses.
A/C System Components
- Compressor - the pump that circulates refrigerant; driven by the engine via a belt and engaged by an electromagnetic clutch
- Condenser - mounted in front of the radiator; releases heat to the outside air
- Receiver-drier or accumulator - removes moisture using a desiccant and stores excess refrigerant
- Expansion valve or orifice tube - restricts flow and drops pressure before the evaporator
- Evaporator - located inside the dash; absorbs heat from cabin air
Refrigerant Types
R-134a has been the standard automotive refrigerant since 1994, replacing R-12 (which depleted the ozone layer). Newer vehicles (2015+) use R-1234yf, which has a much lower global warming potential (GWP). These refrigerants are not interchangeable - each requires specific service equipment, fittings, and compressor oil.
Refrigerant Safety
Never vent refrigerant to the atmosphere - it is illegal under Canadian environmental regulations. Always use a certified recovery machine before opening any A/C system. R-1234yf is mildly flammable and requires specific handling precautions.
A/C Diagnosis
- No cooling - check compressor clutch engagement, refrigerant charge level, and electrical controls
- Insufficient cooling - low refrigerant charge, restricted condenser, or plugged orifice tube
- Musty smell from vents - mold growth on the evaporator; treat with evaporator cleaner
- A/C compressor noise - low oil, worn bearings, or internal damage
The A/C system uses the refrigeration cycle with a compressor, condenser, expansion device, and evaporator. R-134a and R-1234yf are not interchangeable. Never vent refrigerant - always use a recovery machine.