1. Chapter 4 Air-Conditioning Components

2. Standard and Optional Equipment

3. Compressors Usually belt driven from the engine
Usually have an electromagnetic clutch to turn on/off
Two refrigerant lines
suction (larger) draws low pressure, low temp vapor from evaporator
discharge (smaller) lets out high pressure, high temp vapor to the condenser

4. Compressor main functions
Raise the pressure of the refrigerant
When compressed the refrigerant temperature rises (no heat is added by the compressor)
Important for proper heat transfer
Create low pressure in the evaporator
Allows refrigerant to vaporize (boil) absorbing large amounts of heat
Circulate refrigerant and oil

5. Heat of Compression

6. Two Piston Compressor (Requires 14 hp to run)
York

7. Intake stroke draws vapor past the intake reed valve

8. Compression stroke forces intake closed and pushes out compressed vapor through exhaust

9. Swash Plate Compressor (Requires 7hp to run)
Sanden

10. As the swash plate is rotated, pistons move in and out

11. Compressor Maintenance
Oil level needs to be checked when the system is discharged
Compressor seal replacement
Replace valve plates or gaskets (low psi)
Replace electromagnetic clutch
Belt tension

12. Rotary Vane Compressor
Ford used this compressor at one time.

13. Centrifugal Force throws vanes outward sealing them against the wall

14. Variable Displacement Compressor
Compressor runs continually, no clutch cycling. A control valve senses evaporator
load and automatically changes the displacement to meet the system needs.

15. Maximum displacement, wobble plate maximum angle (compressor runs continuously)

16. Minimum displacement, wobble plate minimum angle (compressor runs continuously)

17. Control valve for Variable Displacement
The angle of the swash plate is controlled by the bellows activated control valve, located
in the rear of the head, that senses the suction pressure.

18. Scotch Yoke (R4) opposed pistons
Used in GM, notorious for shaft seal failures, and being very noisy.

19. (Scotch Yoke) Pistons pump by following the contour
Suction valve in the piston.

20. Scroll Compressor (requires very little hp found only on small cars)
Not very common yet, very efficient.

21. Inner scroll draws and compresses during rotation

22. Operation of the Scroll

23. Oil Loss External leak System recovered in a recovery machine
Refrigerant caries out oil
System recovered in a recovery machine
Measure and reinstall
Component replacement
Oil can be trapped in the old component
Hybrid uses dielectric oil

24. Check oil in a new compressor

25. Condenser

26. Key points Heat moves to less warm
Heat transfer quickly with large differences
Fins increase surface area to dissipate heat
Cooling effect causes refrigerant to change states from high psi vapor to high psi subcooled liquid
Must keep clean and fins straight for proper air flow

27. Fin Comb

28. Receiver-Drier Liquid refrigerant from the condenser enters
Filters
Removes moisture
Stores excess
Pickup tube ensures that only liquid exits (properly charged system)
Desiccant is hygroscopic (absorbs moisture)
Different for R-12 and 134a
Moisture reacts with refrigerant to form hydrochloric acid.

29. Receiver-Drier Components

30. Drier Location and Mounting
Located in a cool dry place
Desiccant can absorb more moisture when it is less warm
Mounted vertically
Pickup tube in the bottom to only take liquid
Mounted horizontally
JD uses a side pick-up tube
Make sure “top”

31. Sight Glass R-12 A-normal, B-bubbles, C-oil streaking
Bubbles usually indicate a loss of refrigerant, streaking usually indicates no refrigerant.

32. Moisture Indicator

33. Warning with Weights