GM Service Manual Online
For 1990-2009 cars only

System Performance Test Table

    Important: Be sure to record the relative humidity and ambient temperature conditions at the time of the test.

  1. Park the vehicle inside or in the shade. The ambient temperature must be at least 16° C (60° F).
  2. Open the windows to ventilate the interior.
  3. Vent the engine exhaust.
  4. Open the hood and install the high and low side pressure gauges.
  5. Record the ambient temperature outside.
  6. Record the relative humidity. Use a psychrometer or consult the local weather bureau.
  7. Close the doors and windows.
  8. Set the A/C control assembly to MAX mode with the blower speed set to high, the temperature to full cold and push the A/C button to turn on the A/C on.
  9. Open the A/C air outlet deflectors.
  10. Place a thermometer in the right center A/C outlet.
  11. Place the transaxle in PARK and start the engine, stabilize engine at 2000 RPM.
  12. Run the A/C system until the outlet air reaches the lowest temperature (about 3 minutes).
  13. Record the outlet air temperature and the high side and low side pressures.
  14. Turn the engine off and compare the readings with the data in the A/C Performance Table.
  15. If the readings are out of the temperature and/or pressure limits. Refer to VDOT A/C System Diagnosis .

A/C Performance Table

Relative Humidity

(%)

Ambient Air Temperature

Maximum Low Side Pressure

Engine Speed

(RPM)

Maximum Right Center Air Outlet Temperature

Maximum High Side Pressure

°F

°C

PSIG

kPaG

°F

°C

PSIG

kPaG

20

70

21

37

255

2000

46

8

225

1551

80

27

37

255

47

8

275

1896

90

32

37

255

53

12

325

2241

100

38

38

262

54

12

325

2241

30

70

21

37

255

2000

48

9

240

1655

80

27

37

255

50

10

285

1965

90

32

39

269

57

14

340

2344

100

38

43

262

60

16

360

2482

40

70

21

37

255

2000

49

9

260

1793

80

27

37

255

53

12

305

2103

90

32

42

290

60

16

355

3137

100

38

49

338

66

19

395

2724

50

70

21

37

255

2000

51

11

275

1896

80

27

39

269

56

13

320

2206

90

32

46

317

63

17

375

2586

100

38

55

379

72

22

430

2965

60

70

21

37

255

2000

53

12

290

2000

80

27

42

290

59

15

340

2344

90

32

49

338

66

19

390

2689

100

38

60

414

78

26

445

3068

70

70

21

37

255

2000

55

13

305

2103

80

27

45

310

62

17

355

2448

90

32

53

365

70

21

405

2792

80

70

21

41

283

2000

56

13

320

2206

80

27

48

331

65

18

370

2551

90

32

57

393

73

23

420

2896

90

70

21

45

310

2000

58

14

335

2310

80

27

52

359

68

20

385

2655