GM Service Manual Online
For 1990-2009 cars only
Table 1: A/C Performance Table

Test Description

The following test measures the A/C system operating efficiency by comparing:

    • The ambient air temperature
    • The ambient air humidity
    • The pressure at the high-pressure side of the refrigeration system
    • The pressure at the low-pressure side of the refrigeration system
    • The temperature of the air being discharged into the passenger compartment

The number(s) below refer to the step number(s) on the diagnostic table.

  1. This step determines if there is enough refrigerant in the A/C system in order to operate the system without damage.

  2. This step measures the performance of the A/C system.

  3. This step is to allow for vehicle variations as well as high ambient air temperatures.

Step

Action

Value(s)

Yes

No

Important: 

   • The ambient air temperature must be at least 16°C (60°F) .
   • Do not induce additional air flow across the front of the vehicle during the test.
   • If you were sent here from a DTC diagnostic table, clear the DTC upon completion of this test.

1

  1. Park the vehicle inside or in the shade.
  2. Open the windows in order to ventilate the interior of the vehicle.
  3. If the A/C system was operating, allow the A/C system to equalize (about 2 minutes).
  4. Ensure that the ignition key is in the OFF position.
  5. Install the J 43600 .
  6. Record the ambient air temperature displayed on the J 43600 .
  7. Record readings of the low and high side STATIC pressures.

Are both the low and high side pressures within the specified value?

    • Above 16°C (60°F) - 345 kPa (50 psi)
    • Above 24°C (75°F) - 483 kPa (70 psi)
    • Above 33°C (90°F) - 690 kPa (100 psi)

Go to Step 2

Go to Leak Testing

2

    Important: Record the relative humidity and the ambient air temperature AT THE TIME OF THE TEST.

  1. Close the vehicle doors and windows.
  2. Open the driver door window 5-6 inches.
  3. Set the HVAC control to the following positions:
  4. • The A/C on
    • The blower control to the highest position
    • The HVAC control assembly to discharge air through the A/C outlets
    • The temperature control to the coldest position
    • All A/C outlets OPEN
  5. Install the temperature probes of the J 43600 in the left and right center A/C air outlets.
  6. Apply the parking brake.
  7. Place the transaxle in PARK
  8. Start the engine and allow to idle.
  9. Operate the A/C system for 5 minutes.
  10. Inspect for the following:
  11. •  Abnormal frost areas
    • Unusual noises

    Important: When performing this step it is necessary to press the RESET button on the J 43600 before pressing the PRINT button after the 5 minute operating time.

  12. Record the following information:
  13. • The outlet air temperatures
    • The low-side pressure
    • The high-side pressure
  14. Compare the low and high side pressures and the output temperatures to the table below.

Does all the data recorded fall within the specified ranges of the table below?

--

Go to Step 8

Go to Step 3

3

If the pressures and temperatures recorded do not fall within the specified ranges:

  1. Continue to operate the A/C system for an additional 5 minutes.
  2. Record the pressures and temperatures again.
  3. Compare the low and high side pressures and the output temperature to the table below.

Does all the data recorded fall within the specified ranges of the table below?

--

Go to Step 8

Go to Step 4

4

Do the high and low side pressures fall within the specified ranges but the outlet temperatures do not?

--

Go to Air Conditioning (A/C) Diagnostics - Pressure Zone A

Go to Step 5

5

Is the low side pressure higher than the specified range and the high side pressure within or lower than the specified range?

--

Go to Air Conditioning (A/C) Diagnostics - Pressure Zone B

Go to Step 6

6

Are the low and high side pressures both higher than the specified ranges?

--

Go to Air Conditioning (A/C) Diagnostics - Pressure Zone C

Go to Step 7

7

Is the low side pressure within or lower than the specified range and the high side pressure higher than the specified range?

--

Go to Air Conditioning (A/C) Diagnostics - Pressure Zone D

Go to Step 8

8

Operate the system in order to verify the test results.

Did you find the same results?

--

System OK

Go to Symptoms - HVAC Systems - Manual in HVAC Systems - Manual or Symptoms - HVAC Systems - Automatic in HVAC Systems - Automatic

A/C System Pressure - Zone Classification


Object Number: 634265  Size: MF

A/C Performance Table

Relative Humidity

Ambient Air Temperature

Maximum Low Side Pressure

Engine Speed

Maximum Right Center Air Outlet Temperature

Maximum High Side Pressure

%

°F

°C

PSI

kPa

RPM

°F

°C

PSI

kPa

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

296

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