Automotive AC
10 LessonsRefrigerant cycles, compressor diagnosis, and AC performance testing.
Overview
Air conditioning is one of the most profitable services in the shop. This module covers the refrigeration cycle, compressor types, condenser and evaporator operation, expansion devices, refrigerant handling, and the systematic approach to diagnosing AC performance complaints.
Key Components
- AC compressor and clutch
- Condenser
- Evaporator
- Expansion valve / orifice tube
- Receiver-drier / accumulator
How It Works
The AC system moves heat from inside the cabin to outside the vehicle using refrigerant that changes state between liquid and gas. The compressor pressurizes refrigerant (hot, high-pressure gas), the condenser cools it to a liquid, the expansion device drops the pressure (cold), and the evaporator absorbs cabin heat as the refrigerant boils back to a gas.
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Join the Nation — FreeCommon Problems
- Refrigerant leak from O-ring or condenser
- Compressor clutch not engaging
- Blend door actuator failure (hot on one side)
- Condenser blockage from debris
- Evaporator freeze-up from low refrigerant
Diagnostic Tips
- Manifold gauge readings tell the whole story
- UV dye is the best leak detection method
- Check compressor clutch gap and voltage
- Vent temperature should be 35-45°F at idle with max AC
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