GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1998 🢒 LeSabre 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 System Performance Test

    Important: 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 in order to ventilate the vehicle.
  3. Vent the engine exhaust.
  4. Open the hood and install the J 39183-C
  5. Record the ambient temperature where the vehicle is parked.
  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. Ensure that the vent button LED is not illuminated.
  9. Open the A/C air outlet deflectors.
  10. Place a thermometer in the left center A/C outlet.
  11. Place the transaxle in PARK. Start the engine. Let the engine idle.
  12. Run the A/C system until the outlet air reaches a stabilized 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. Normally operating A/C systems should not exceed levels shown.
  15. If the readings exceed the table limits. Refer to High Side vs. Low Side Pressure Table and Gray Area Diagnosis and Service in Cooling Insufficient.
  16. If you were sent here from a DTC diagnostic table be sure to clear the DTC upon completion.

A/C Performance Table

Temperature

Humidity

Low Side Service Port Pressure in PSIG

High Side Service Port Pressure in PSIG

A/C Discharge Temperature

16°C (60°F)

Less than 40

28-34

110-130

6-8°C (42-46°F)

High

32-38

160-190

7-8°C (44-46°F)

21°C (70°F)

Less than 40

30-34

190-210

3-6°C (38-43°F)

High

34-40

200-220

7-9°C (44-48°F)

27°C (80°F)

Less than 40

28-36

160-180

4-7°C (40-45°F)

High

38-36

170-190

6-9°C (43-48°F)

32°C (90°F)

Less than 40

34-40

180-200

6-9°C (43-48°F)

High

34-40

190-210

7-10°C (44-50°F)

38°C (100°F)

Less than 40

38-46

200-220

9-12°C (48-54°F)

High

42-50

210-250

13-17°C (56-62°F)

43°C (110°F)

Less than 40

48-60

280-340

16-20°C (60-68°F)

High

54-64

340-360

21-23°C (70-74°F)

49°C (120°F)

Less than 40

56-64

320-360

17-22°C (62-72°F)