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Aut 236

Aut 236. Automotive Climate Control Systems. Heating & Air Conditioning Review. Theory of Automotive Air Conditioning Heat Flow Heat Absorption Pressure and Boiling Points. Heating & Air Conditioning. REFRIGERATION. COOLING BY THE REMOVAL OF HEAT. Heating & Air Conditioning.

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Aut 236

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  1. Aut 236 Automotive Climate Control Systems

  2. Heating & Air Conditioning Review • Theory of Automotive Air Conditioning • Heat Flow • Heat Absorption • Pressure and Boiling Points

  3. Heating & Air Conditioning REFRIGERATION COOLING BY THE REMOVAL OF HEAT

  4. Heating & Air Conditioning

  5. Heating & Air Conditioning • STATES OF MATTER, (WATER) • Solid

  6. Heating & Air Conditioning • STATES OF MATTER, (WATER) • Liquid

  7. Heating & Air Conditioning • STATES OF MATTER, (WATER) • Vapor

  8. Heating & Air Conditioning • Heat Measurement • Apply 1 BTU, to 1 lb of water, you will raise the temperature by 1° F

  9. Heating & Air Conditioning

  10. Heating & Air Conditioning

  11. Heating & Air Conditioning • Latent Heat Principle

  12. Heating & Air Conditioning

  13. Heating & Air Conditioning • Temperature/Pressure Relationship of Refrigerant

  14. Heating & Air Conditioning • Summary of A/C Principles • Heat always moves from a warmer object to a cooler object. • When liquids are heated to a vapor state, heat is absorbed. • When a gas condenses from a vapor to a liquid state, heat is released. • The temperature at which a substance changes state is affected by pressure.

  15. Heating & Air Conditioning • The Clean Air Act. • CFC free Refrigerants • Refrigerant recovery • Certification

  16. Basic Refrigerant Cycle

  17. Heating & Air Conditioning • The Air Conditioning System and its Components

  18. System Types • Cycling clutch with thermostatic expansion valve (CCTXV) • Cycling clutch with orifice tube (CCOT) • Variable compressor with thermostatic expansion valve (VDTXV) • Variable compressor with orifice tube (VDOT)

  19. Ambient temperature switch – Prevents compressor from operating if OAT is too low. Thermostatic switch Cycling clutch system – stops comp if evaporator is at freezing point. Pressure cycling switch – turns compressor on and off at pre-set levels Low-pressure cut-off switch – cuts off compressor if pressure on high side is too low. High-pressure cut-out switch – cuts off compressor if discharge pressure is too high. High-pressure relief valve – relieves excess system pressure to prevent damage to system (approx. 440 PSIG Compressor control valve – used in variable displacement compressors to vary the stroke of the piston. Electronic cycling clutch switch – Prevents evap. freezing by monitoring suction line temp. Compressor Controls

  20. Heating & Air Conditioning • Compressor – The heart of the system, pumps refrigerant through the A/C system and increases the pressure of the refrigerant. • Located under the hood. Belt driven. • Inadequate lubrication inside the compressor will cause excessive wear, contamination and the spread of particles throughout the A/C system

  21. Heating & Air Conditioning • Piston type Compressor

  22. Heating & Air Conditioning • Variable displacement Compressor

  23. Compressor Operation • This double piston strokes back and forth as the swash plate rotates. In this view, the piston is moving to the left, the right end is on a suction stroke with refrigerant entering from the suction port, and the left end is on a discharge stroke, forcing refrigerant out the discharge port.

  24. Rotary Compressors Many modern vehicles use a vane (shown) or a scroll compressor. The pumping member of these compressors rotate to increase the pressure and move the refrigerant into the high side.

  25. Heating & Air Conditioning • Manifold -- Connects the suction and discharge lines to the compressor. • Metal particles adhering to the internal walls are evidence of system-wide contamination

  26. Heating & Air Conditioning • Condenser – Heat exchanger. • Refrigerant changes state from a high-pressure gas to a high-pressure liquid. • Located in front of radiator. • The small passages inside the condenser are very susceptible to clogging from particles.

  27. Heating & Air Conditioning • Condenser

  28. CONDENSER AIR FLOW

  29. CONDENSERS REJECT HEAT • PURE LIQUID

  30. CONDENSER TEMPERATURES • PURE LIQUID

  31. CONDENSER SUMMARY • Refrigerant Enters As: • *High Pressure • *High Temperature • *Vapor • Refrigerant Leaves As: • *High Pressure • *High Temperature • *Sub-Cooled Liquid

  32. Heating & Air Conditioning • Liquid Line – Allows for movement of refrigerant through the system. • Particles frequently cling to the interior walls and catch other particles as they flow through.

  33. METERING DEVICE FUNCTION • * • Provides a pressure drop which • separates the high side from the • low side of the system • * • Meters refrigerant into the • evaporator

  34. Heating & Air Conditioning • Orifice Tube -- Regulates refrigerant flow to the evaporator and changes refrigerant pressure from high to low. • Located under the hood. • Will become clogged by system contamination.

  35. Heating & Air Conditioning • Regulates refrigerant flow to the evaporator and changes refrigerant pressure from high to low. • Located under the hood. • Will become clogged by system contamination.

  36. Heating & Air Conditioning

  37. Heating & Air Conditioning • Evaporator -- Refrigerant changes state from low-pressure liquid to low-pressure gas. • Located in the passenger compartment. • In most cases of system contamination, the evaporator will not need replacement. Most particles that reach the evaporator tend to flow through.

  38. EVAPORATOR COILS - 2

  39. EVAPORATOR COILS - 1 • LIQUID / VAPOR MIXTURE • 53° F • EXPANSION • VALVE • PURE GAS • LIQUID REFRIGERANT

  40. EVAPORATOR SUMMARY • Refrigerant Enters As: • *Low Pressure • *Low Temperature • *Saturated (liquid/vapor) Mixture • Refrigerant Leaves As: • *Low Pressure • *Low Temperature • *Superheatd Gas

  41. Heating & Air Conditioning • Accumulator -- Stores excess refrigerant not utilized by evaporator, filters contaminants and moisture out of refrigerant. • Used in orifice tube systems • Located under the hood just before the compressor. • Due to the concentrations of particles that are trapped here, the accumulator frequently requires replacement.

  42. Heating & Air Conditioning • Receiver/Dryer • Similar function as accumulator. • Used in THX systems. • Located before the evaporator.

  43. Heating & Air Conditioning • Compressor Clutches

  44. Heating & Air Conditioning • The Air Conditioning System and Components QUESTIONS?

  45. Heating & Air Conditioning

  46. Heating & Air Conditioning

  47. Heating & Air Conditioning

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