GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1998 🢒 Silhouette 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 System Performance Test

Performance Test

Tools Required

J 39500-B ACR4 Station

Before you perform the A/C system performance test, perform a functional test in order to ensure that the following conditions exist.

    • The air delivery system valves are functioning.
    • The routing air passes through the evaporator to the cutlets.

Refer to the applicable chart below:

Performance testing measures the A/C system operating efficiency by comparing the following figures:

    • 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
  1. Park the vehicle inside or in the shade.
  2. Open the windows in order to ventilate the interior of the vehicle.
  3. Vent the engine exhaust.
  4. Open the hood.
  5. Install the the following gauges.

    6. Route the lines over the rear hood seal.

    Tape the gauges to the windshield for viewing by the driver:

    • The high-side pressure gauge
    • The low-side pressure gauge
  6. Close the hood.
  7. Record the ambient temperature at the vehicle.

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

  8. Record the relative humidity, using one of the following methods:
    9. • Use a psychrometer.
    • Consult the local weather bureau.
  9. Close the doors and windows.
  10. Set the mode control to the following settings:
    11. • The A/C control set to A/C
    • The blower control on HIGH
    • The temperature controls on FULL COLD
  11. Open the A/C outlets.
  12. Place the thermometer in the right center A/C outlet.
  13. Place the transaxle in one of the following positions:
    14. • PARK
    • NEUTRAL
  14. Start the engine.
  15. Stabilize the engine at 2000 RPM.

    16. Then, start the timer.

  16. Run the A/C system until the outlet air reaches the lowes temperature.

    17. This will take about 3 minutes.

  17. Record the following information:
    18. • The outlet air temperature
    • The high-side pressure
    • The low-side pressure
  18. Turn the engine OFF.
  19. Compare the readings with the upper limit data that is located in the A/C Performance Test table below.

    20. A normally operating A/C system should not exceed the levels that are shown in the table.

  20. If you suspect a malfunction in the refrigerant system due to abnormal system pressures, perform the following steps:
    21. • Inspect the outer surfaces of the radiator and condenser cores to ensure that the air flow is not blocked by any of the following objects.
    • Inspect between the condenser and the radiator, as well as the outer surfaces:
       - Dirt
       - Leaves
       - Other foreign material
    • Inspect for restrictions in the following areas:
       - The evaporator core
       - The condenser core
    • Inspect for kinks in the following areas:
       - The evaporator core hoses or tubes
       - The condenser core hoses or tubes
    • Inspect for refrigerant leaks.
    • Inspect all of the air ducts for the following situations.
    • Low air flow rate may indicate a restricted evaporator core:
       - Leaks
       - Restrictions
    • Inspect for compressor clutch slippage.
    • Inspect for the improper drive belt tension.
    • Inspect for a plugged accumulator.
    • Inspect for a plugged expansion (orifice) tube.

Relative Humidity

Ambient Air Temp

Low Side Pressure

Engine Speed

High Side Pressure

Center Air Outlet Temp Front System

Center Air Outlet Temp Rear System

Metric

English

Metric

English

Metric

English

Metric

English

Metric

English

10%

21°C

70°F

N/A

N/A

2000 RPM

N/A

N/A

N/A

N/A

N/A

N/A

27°C

80°F

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

32°C

90°F

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

38°C

100°F

kPa

psi

kPa

psi

°C

°F

°C

°F

43°C

110°F

kPa

psi

kPa

psi

°C

°F

°C

°F

20%

21°C

70°F

kPa

psi

2000 RPM

kPa

psi

°C

°F

°C

°F

27°C

80°F

207 kPa*

30 psi*

1517 kPa*

220 psi*

10°C*

50°F*

11°C*

51°F*

32°C

90°F

221 kPa

32 psi

1724 kPa

250 psi

12°C

53°F

12°C

53°F

38°C

100°F

262 kPa

38 psi

2206 kPa

320 psi

14°C

58°F

16°C

60°F

°C

F

kPa

psi

kPa

psi

°C

°F

°C

°F

30%

20°C

70°F

207 kPa*

30 psi*

2000 RPM

1517 kPa*

220 psi*

10°C*

50°F*

11°C

51°F

27°C

80°F

241 kPa

35 psi

1793 kPa

260 psi

13°C

56°F

13°C

56°F

32°C

90°F

262 kPa

38 psi

2165 kPa

314 psi

15°C

59°F

16°C

60°F

38°C

100°F

310 kPa

45 psi

2517 kPa

365 psi

18°C

64°F

18°C

64°F

°C

°F

kPa

psi

kPa

psi

°C

°F

°C

°F

40%

21°C

70°F

207 kPa*

30 psi*

2000 RPM

1586 kPa*

230 psi*

11°C*

51°F*

11°C

51°F

27°C

80°F

269 kPa*

39 psi*

2069 kPa*

300 psi*

15°C*

59°F*

15°C

50°C

32°C

90°F

296 kPa

43 psi

2448 kPa

355 psi

18°C

65°F

18°C

65°F

38°C

100°F

359 kPa

52 psi

2689 kPa

390 psi

22°C

72°F

22°C

72°F

43°C

110°F

kPa

psi

kPa

psi

°C

°F

50%

21°C

70°F

228 kPa*

33 psi*

2000 RPM

1827 kPa*

265 psi*

13°C*

55°F*

13°C

55°F

27°C

80°F

290 kPa

42 psi

2213 kPa

321 psi

17°C

63°F

17°C

63°F

32°C

90°F

310 kPa

45 psi

2482 kPa

360 psi

21°C

70°F

21°C

70°F

38°C

100°F

372 kPa

54 psi

2724 kPa

395 psi

24°C

76°F

24°C

76°F

43°C

110°F

kPa

psi

kPa

psi

°C

°F

°C

°F

60%

21°C

70°F

241 kPa*

35 psi*

2000 RPM

1896 kPa*

275 psi*

13°C*

55°F*

13°C

55°F

27°C

80°F

290 kPa*

42 psi*

2241 kPa*

325 psi*

16°C*

60°F*

16°C

60°F

32°C

90°F

317 kPa

46 psi

2482 kPa

360 psi

18°C

64°F

18°C

64°F

38°C

100°F

379 kPa

55 psi

2724 kPa

395 psi

22°C

71°F

23°C

73°F

43°C

110°F

kPa

psi

kPa

psi

°C

°F

°C

°F

70%

21°C

70°F

248 kPa*

36 psi*

2000 RPM

1931 kPa*

280 psi*

11°C*

51°F*

11°C

51°F

27°C

80°F

296 kPa*

43 psi*

2344 kPa*

340 psi*

14°C*

58°F*

15°C

59°F

32°C

90°F

331 kPa

48 psi

2482 kPa

360 psi

18°C

65°F

19°C

67°F

38°C

100°F

379 kPa

55 psi

2758 kPa

400 psi

23°C

74°F

23°C

74°F

43°C

110°F

kPa

psi

kPa

psi

°C

°F

°C

°F

80%

21°C

70°F

331 kPa*

48 psi*

2000 RPM

1965 kPa*

285 psi*

10°C*

50°F*

11°C

51°F

27°C

80°F

310 kPa

45 psi

2379 kPa

345 psi

13°C

56°F

14°C

58°F

32°C

90°F

338 kPa

49 psi

2482 kPa

360 psi

19°C

67°F

21°C

69°F

38°C

100°F

kPa

psi

kPa

psi

°C

°F

°C

°F

43°C

110°F

kPa

psi

kPa

psi

°C

°F

°C

°F

90%

21°C

70°F

262 kPa*

38 psi*

2000 RPM

2000 kPa*

290 psi*

15°C*

59°F*

16°C

60°F

27°C

80°F

338 kPa

49 psi

2413 kPa

350 psi

16°C

61°F

17°C

62°F

32°C

90°F

kPa

psi

kPa

psi

°C

°F

°C

°F

38°C

100°F

kPa

psi

kPa

psi

°C

°F

°C

°F

43°C

110°F

kPa

psi

kPa

psi

°C

°F

°C

°F

Important: This chart is to be used in conjunction with the appropriate diagnostic table(s).

* This data reflects the performance obtained while the engine cooling fans were operating in series (low speed), rather than in parallel (high speed).