1. FIGURE 8-1 Both TXV (a) and OT (b) A/C systems have five major components. (Courtesy of ACDelco)

2. FIGURE 8-2 Some of the variety of compressors a and l use a crankshaft; b, d, e, f, h, and i use a swash plate; c and g use a wobble plate with a variable stroke; e and m use a Scotch yoke; j and k use a plain wobble plate; and n is a vane compressor. (Courtesy of Everco Industries)

3. FIGURE 8-2 (CONTINUED) Some of the variety of compressors a and l use a crankshaft; b, d, e, f, h, and i use a swash plate; c and g use a wobble plate with a variable stroke; e and m use a Scotch yoke; j and k use a plain wobble plate; and n is a vane compressor. (Courtesy of Everco Industries)

4. FIGURE 8-3 This compressor is compatible with both R-134a and R-12 and is available in three different capacities or displacements, with one of seven different clutch configurations of either 12 or 24 volts, and with one of seven different rear head and line port configurations. (Courtesy of Seltec)

5. FIGURE 8-4 Rotation of the swash plate causes these double pistons to move through the suction and discharge strokes. Evaporator pressure fills the cylinders with refrigerant during the suction stroke. This refrigerant is pumped into the high side during the discharge stroke.

6. FIGURE 8-5 The displacement of a compressor is determined by the length of the stroke, diameter of the cylinders (bore), and number of cylinders.

7. FIGURE 8-6 A 2-cylinder compressor creates 2 large pumping pulses per revolution. A 10-cylinder compressor (same displacement) creates 10 smaller pulses; its operation is much smoother.

8. FIGURE 8-7 The Tecumseh (left) and York 2-cylinder,inline compressors were very common at one time. (Courtesy of Four Seasons)

9. FIGURE 8-8 A York 209 compressor (a) and a more compact mini series (b). York compressors can be identified by part number and crankshaft appearance (c). (Courtesy of Four Seasons)

10. FIGURE 8-8 (CONTINUED) A York 209 compressor (a) and a more compact mini series (b). York compressors can be identified by part number and crankshaft appearance (c). (Courtesy of Four Seasons)

11. FIGURE 8-9 A Tecumseh HG 850 or HG 1000 (a) is identified by part number. The HG 500 (b) is a single-cylinder compressor. (Courtesy of Four Seasons)

12. FIGURE 8-10 The two pistons in a Chrysler V compressor are arranged in a V shape. (Courtesy of ACDelco)

13. FIGURE 8-11 An R-4 compressor has two pairs of pistons that are driven by a Scotch yoke. (Courtesy of Visteon)

14. FIGURE 8-12 Note how rotation of the swash plate causes the pistons to slide through their strokes. Balls and shoes act as bearings between the swash plate and pistons. (Courtesy of Zexel USA Corporation)

15. FIGURE 8-13 The suction (a) and discharge (b) crossover circuits of a swash-plate compressor transfer refrigerant to and from the cylinders at the other end. Note how oil from the suction crossover lubricates the internal parts. (Reprinted with permission of General Motors Corporation)

16. FIGURE 8-14 A disassembled view of an A-6 compressor; this compressor was very popular during the 1960s, 1970s, and early 1980s. (Courtesy of ACDelco)

17. FIGURE 8-15 A disassembled view of a DA-6 compressor; this compressor replaced the A-6. (Courtesy of ACDelco)

18. FIGURE 8-16 Three versions of Denso compressors; note the different mounting bosses. (Courtesy of Four Seasons)

19. FIGURE 8-17 This Zexel compressor uses a swash-plate design
FIGURE 8-17 This Zexel compressor uses a swash-plate design. (Courtesy of Zexel USA Corporation)

20. FIGURE 8-18 Rotation of the drive hub causes the wobble action of the wobble plate and forces the single pistons to move through their strokes. (Courtesy of Zexel USA Corporation)

21. FIGURE 8-19 A variable displacement compressor can change the angle of the wobble plate and piston stroke. This angle is changed by a control valve that senses evaporator pressure, which in turn changes wobble chamber pressure. (Courtesy of Zexel USA Corporation)

22. FIGURE 8-20 Two of the DA6 and HR6 versions of the front head (left and center) and a view of the rear head (right). (Courtesy of ACDelco)

23. FIGURE 8-21 The piston stroke of this variable displacement compressor is controlled by crankcase pressure, which is adjusted using an electric solenoid (right). (Courtesy of Toyota Motor Sales USA, Inc.)

24. FIGURE 8-22 A compact variable displacement compressor
FIGURE 8-22 A compact variable displacement compressor. Note the pistons use a spherical bearing to connect to the wobble plate. (Courtesy of Delphi Corp., all rights reserved)

25. FIGURE 8-23 An electric compressor with its bright orange HV wires for power (a). Another compressor that combines a belt driven scroll with an electrically driven scroll (b).

26. FIGURE 8-24 The decal on this compressor identifies the type (SDB709) and the serial number. Note also that it uses a seven-groove, multi-V clutch, four mounting bolts, and vertical-pad service ports at the side.

27. FIGURE 8-25 A cutaway (a) and exploded (b) view of a clutch assembly showing the major parts. (a. Courtesy of Warner Electric; b. Courtesy of ACDelco)

28. FIGURE 8-26 In most clutches, the coil is stationary, secured to the compressor (a). In a rotating field clutch, the coil is built into the rotor, and a brush assembly is used to conduct electricity into and out of the coil (b). (Courtesy of Warner Electric)

29. FIGURE 8-27 Most compressors use three-piece clutches as shown here (a). The rotor is driven by a belt, the hub drives the compressor shaft, and the coil is secured to the compressor (b). (Courtesy of Warner Electric)

30. FIGURE 8-27 (CONTINUED) Most compressors use three-piece clutches as shown here (a). The rotor is driven by a belt, the hub drives the compressor shaft, and the coil is secured to the compressor (b). (Courtesy of Warner Electric)

31. FIGURE 8-28 The magnetic flux path is from the coil and through the metal of the rotor and clutch hub. When it meets a pole groove, it travels from the hub to the rotor or vice versa, which increases the clutch holding power.

32. FIGURE 8-29 The plastic shield on the front of this clutch hub (a) is a thermal fuse; if it gets too hot, it will melt and cause the clutch to fail before compressor damage occurs (b). (Courtesy of Warner Electric)

33. FIGURE 8-30 This damper drive is a one-piece pulley and hub
FIGURE 8-30 This damper drive is a one-piece pulley and hub. Torque is transferred from the pulley through the rubber damper (a), and another damper-drive type uses torque-limiting metal fingers that will shear if the compressor should seize.

34. FIGURE 8-31 The shaft seal must keep refrigerant from escaping out the front of the compressor. Most compressors have an oil flow routed to them to reduce wear and improve the sealing action. (Courtesy of Toyota Motor Sales USA, Inc.)

35. FIGURE 8-32 Many compressors use a two-piece seal with a rotating carbon seal and a stationary seal. (Courtesy of ACDelco)

36. FIGURE 8-33 Some newer compressors use a stationary lip seal that seals against the rotating shaft. (Courtesy ACDelco)

37. FIGURE 8-34 Older compressors pumped oil through passages in the crankshaft to lubricate moving parts. (Courtesy of Toyota Motor Sales USA, Inc.)

38. FIGURE 8-35 Some refrigerants and PAG oils are very hygroscopic and absorb moisture more rapidly than other oils, such as the polyol ester Icematic. (Courtesy of Castrol North America)

39. FIGURE 8-36 This compressor separates oil from the refrigerant leaving the compressor to improve compressor lubrication. (Courtesy of Toyota Motor Sales USA, Inc.)

40. FIGURE 8-37 The major types of refrigerant oil, the refrigerant it is used with, and the viscosities in which it is commonly available.

41. FIGURE 8-38 The oil in a system migrates when the system is operated (a), and the migration is slightly different in R-12 and R-134a systems (b). (a Courtesy of ACDelco)

42. FIGURE 8-38 (CONTINUED) The oil in a system migrates when the system is operated (a), and the migration is slightly different in R-12 and R-134a systems (b). (a Courtesy of ACDelco)

43. FIGURE 8-39 This V-5 20 compressor has a control valve (18), a control switch (22), and a pressure relief valve mounted in the near head. (Courtesy of ACDelco)

44. FIGURE 8-40 Three major types of condensers (a)
FIGURE 8-40 Three major types of condensers (a). The heat rejection and air-side pressure drop are shown in (b). (Courtesy of Delphi Corp., all rights reserved)

45. FIGURE 8-40 (CONTINUED) Three major types of condensers (a)
FIGURE 8-40 (CONTINUED) Three major types of condensers (a). The heat rejection and air-side pressure drop are shown in (b). (Courtesy of Delphi Corp., all rights reserved)

46. FIGURE 8-41 The common condenser tube sizes
FIGURE 8-41 The common condenser tube sizes. Modern extruded tube condensers have up to 18 small ports or passages through the tube. Actual size is less than one-half of the drawing size.

47. FIGURE 8-42 A pair of electric fans is used to pull air through the radiator and condenser. (Courtesy of Toyota Motor Sales USA, Inc.)

48. FIGURE 8-43 The foam seals at the front sides of this condenser force all of the air to flow through the condenser and prevent any air flow around or past it.

49. FIGURE 8-44 An internal equalized TXV
FIGURE 8-44 An internal equalized TXV. Note the internal passage to bring evaporator inlet pressure to the bottom of the diaphragm and the screen, which stops debris that might plug the valve (a). The valve is opened by gas pressure on top of the diaphragm and closed by pressure from the evaporator and the superheat spring (b). (Reprinted with permission of General Motors Corporation)

50. FIGURE 8-45 An internal equalized TXV has two large connectors for the liquid line and evaporator (a); an external equalized TXV has an additional smaller line to connect to the evaporator outlet (b); and a block-type TXV has four openings that connect to the evaporator, liquid line, and suction line.

51. FIGURE 8-46 A block TXV has the control head next to where the cooled gas is leaving the evaporator, eliminating the need for a thermal bulb and capillary tube. Note that this valve uses spring-lock fittings. (Courtesy of Chrysler LLC )

52. FIGURE 8-47 Depending on available parts, a VIR assembly can be taken apart and repaired. (Courtesy of ACDelco)

53. FIGURE 8-48 Most OTs are small brass tubes with a filter screen at each end (a); some use a group of plastic beads (b); and an electronic OT has a solenoid so it can change orifice size. (Courtesy of ACDelco)

54. FIGURE 8-49 A flow rate of a VOV as compared to a fixed orifice tube
FIGURE 8-49 A flow rate of a VOV as compared to a fixed orifice tube. Note how the VOV is either larger or smaller under certain conditions (a) and produces cooler discharge air (b). (Courtesy of Nartron Corporation)

55. FIGURE 8-50 This VOV uses a bimetal coil to sense the temperature of the refrigerant. A higher temperature will cause the coil to expand and partially close the variable port to increase the restriction. (Courtesy of Chrysler LLC)

56. FIGURE 8-51 In a VOV (a), the valve is inside the tubular portion at the left; it has the ability to reduce the flow rate as head pressure increases (b). (Courtesy of Nartron Corporation)

57. FIGURE 8-52 A plate-type evaporator (a) is made from a group of plates that form the passages for the gas flow. Note that this one has an antibacterial agent to help prevent foul odors (b). A fin-and-tube evaporator (c) routes the refrigerant flow through one or more tubes. (a. Courtesy of Toyota Motor Sales USA, Inc; b. Courtesy of Four Seasons)

58. FIGURE 8-52 (CONTINUED) A plate-type evaporator (a) is made from a group of plates that form the passages for the gas flow. Note that this one has an antibacterial agent to help prevent foul odors (b). A fin-and-tube evaporator (c) routes the refrigerant flow through one or more tubes. (a. Courtesy of Toyota Motor Sales USA, Inc; b. Courtesy of Four Seasons)

59. FIGURE 8-53 The evaporator used with a POA valve has a small-diameter tube to carry oil from the bottom of the evaporator to the POA outlet. (Courtesy of ACDelco)

60. FIGURE 8-54 This accumulator has an accumulator tube that connects the evaporator outlet and a suction hose that connects to the compressor inlet.

61. FIGURE 8-55 This cutaway accumulator shows the vapor inlet and outlet connected to the compressor, a baffle to keep liquid out of the inlet, the desiccant bag, and an oil bleed hole with filter screen. (Courtesy of Chrysler LLC)

62. FIGURE 8-56 This accumulator has large inlet and outlet fittings and two smaller ports, one for a pressure switch and the other for low-side service. (Courtesy of ACDelco)

63. FIGURE 8-57 Receiver–driers use threaded line connections (a), block-type connections (b), and spring-lock connections (c). (Courtesy of Four Seasons)

64. FIGURE 8-58 This cutaway receiver–drier shows the filter pads and desiccant; many units include a filter at the opening of the pickup tube. Note the sight glass at the top of the pickup tube.

65. FIGURE 8-59 The modulator is built as part of the condenser and includes a removable plug that allows desiccant replacement.

66. FIGURE 8-60 An exploded view of a VIR assembly; note the two valves and the receiver–drier portions. (Courtesy of Four Seasons)

67. FIGURE 8-61 Aftermarket inline filters can be added to a system to trap debris. Some include a replacement OT.

68. FIGURE 8-62 This muffler is a simple expansion or pulsation chamber; some mufflers have internal baffles to help smooth compressor pressure pulses.

69. FIGURE 8-63 A/C fitting types include male O-ring (a), female O-ring (b) ,male flare (c), female flare (d), male insert O-ring (e), push-on barb (f), and beadlock (g). (Courtesy of Four Seasons)

70. FIGURE 8-63 (CONTINUED) A/C fitting types include male O-ring (a), female O-ring (b) ,male flare (c), female flare (d), male insert O-ring (e), push-on barb (f), and beadlock (g). (Courtesy of Four Seasons)

71. FIGURE 8-63 (CONTINUED) A/C fitting types include male O-ring (a), female O-ring (b) ,male flare (c), female flare (d), male insert O-ring (e), push-on barb (f), and beadlock (g). (Courtesy of Four Seasons)

72. FIGURE 8-64 This suction and liquid hose has block fittings for the connections to the receiver–drier, TXV, and compressor; they are sealed by gaskets or O-rings. (Courtesy of Four Seasons)

73. FIGURE 8-65 Standard O-rings merely slide onto the line; captive O-rings are positioned in a groove; dual O-rings have a groove for each O-ring; and a block fitting has a groove for the O-ring. (Courtesy of ACDelco)

74. FIGURE 8-66 A spring-lock fitting is a type of quick-disconnect fitting that is sealed by two O-rings and held together by a garter spring. A special tool is required to expand the garter spring to release the fitting.

75. FIGURE 8-67 A plastic clamp latches over the Quick Joint of the two tubes and locks them together. (Courtesy of Toyoto Motor Sales USA, Inc.)

76. FIGURE 8-68 This barrier-type hose is made from five layers of different materials. (Courtesy of Dayco Products, Inc.)

77. FIGURE 8-69 Most OEM hoses use a captive ferrule (a) that greatly increases the holding power; the ferrule is connected to the metal tubing (b). (a. Courtesy of Chrysler LLC; b. Courtesy of ACDelco)

78. FIGURE 8-70 Some of the switches used in A/C electrical circuits
FIGURE 8-70 Some of the switches used in A/C electrical circuits. (Courtesy of Everco Industries)

79. FIGURE 8-71 Many early A/C systems use a simple electrical circuit as shown.

80. FIGURE 8-72 A switch (a) can open or close a circuit
FIGURE 8-72 A switch (a) can open or close a circuit. A relay (b) does the same thing but can control more current. Most relays are controlled through switches (c). (a. Courtesy of Everco Industries; b. Courtesy of Four Seasons)

81. FIGURE 8-72 (CONTINUED) A switch (a) can open or close a circuit
FIGURE 8-72 (CONTINUED) A switch (a) can open or close a circuit. A relay (b) does the same thing but can control more current. Most relays are controlled through switches (c). (a. Courtesy of Everco Industries; b. Courtesy of Four Seasons)

82. FIGURE 8-73 A pressure switch
FIGURE 8-73 A pressure switch. The contacts are closed by gas pressure on the diaphragm; they are opened by the spring.

83. FIGURE 8-74 Some STVs are connected into the suction line (a), some are combined with the TXV (b), and some are mounted in the compressor inlet (c). (b. Courtesy of ACDelco; c. Courtesy of Everco Industries)

84. FIGURE 8-74 (CONTINUED) Some STVs are connected into the suction line (a), some are combined with the TXV (b), and some are mounted in the compressor inlet (c). (b. Courtesy of ACDelco; c. Courtesy of Everco Industries)

85. FIGURE 8-74 (CONTINUED) Some STVs are connected into the suction line (a), some are combined with the TXV (b), and some are mounted in the compressor inlet (c). (b. Courtesy of ACDelco; c. Courtesy of Everco Industries)

86. FIGURE 8-75 The POA valve in this system closes when evaporator pressure begins to drop too low. Evaporator temperature is kept just above icing. (Courtesy of Everco Industries)

87. FIGURE 8-76 This dual A/C system uses a TXV at both the front and rear cooling units. A magnetic valve is used to positively shut off the flow to either unit. Note how the liquid and suction lines split to the two units. (Courtesy of Toyota Motor Sales USA, Inc.)

88. FIGURE 8-77 Aftermarket A/C systems are available that fit the evaporator under the dash of cars and pickups (a),under the seats (b), in the side panels (c), or in the roofs of vans (d). (Courtesy of Acme Radiator & Air Conditioning)

89. FIGURE 8-78 Rooftop A/C units that contain most of the A/C system are used in trucks, tractors, and various other vehicles. Assembled (a) and exploded (b) views are shown. (Courtesy of Red Dot Corporation)