A/C PERFORMANCE CHECK FUNCTIONING PER DESIGN INTENT

Models Affected: 1988 GRAND PRIX

To evaluate customer comments of reduced A/C performance, use the following procedure and upper limit performance data to determine if the air conditioning system is functioning per design intent on 1988 Grand Prix vehicles.

TEST PROCEDURE

1. Park vehicle inside or in shade.

2. Open windows to ventilate interior.

3. Vent engine exhaust.

4. Install high and low side pressure gages. Route lines over rear hood seal and tape gages to windshield for viewing by driver.

5. Close hood.

6. Record ambient temperature at vehicle.

7. Record relative humidity. Use psychrometer or consult local weather bureau.

8. Close doors and windows.

9. Set air conditioning controls: Outside Air ("NORM") High Blower Full Cold

10. Open A/C outlets.

11. Place thermometer in right center A/C outlet.

12. Place transmission in Park or Neutral, start engine, stabilize at 2000 RPM and start timer.

13. Run until outlet air temperature reaches lowest temperature (about 3 minutes).

14. Record outlet air temperature and high side and low side pressures.

15. Compare readings with upper limit data in attached chart. A normal operating vehicle should not exceed levels shown. If values are exceeded, proceed with diagnostic procedure in Service Manual.

NOTICE: RELATIVE HUMIDITY AND AMBIENT TEMPERATURES AFFECT OUTLET TEMPERATURES. IT IS VERY IMPORTANT TO RECORD CONDITIONS AT TIME OF TEST.

WARRANTY INFORMATION

Labor Operation: T1382

Labor Time : .5 Hours

1988 GRAND PRIX A/C PERFORMANCE CHART UPPER LIMIT

RIGHT CENTER RELATIVE AMBIENT AIR OUTLET AIR LOW SIDE HIGH SIDE HUMIDITY TEMPERATURE TEMPERATURE PRESSURE PRESSURE % F DEG. C DEG. F DEG. C DEG. PSIG KPA PSIG KPA -------- ------ ------ ------ ------ ---- --- ---- --- 20 70 21 43 6 32 221 175 1207 80 27 44 7 32 221 225 1551 90 32 50 10 32 221 275 1896 100 38 51 11 33 228 275 1896

30 70 21 45 7 32 221 190 1310 80 27 47 8 32 221 235 1620 90 32 54 12 34 234 290 2000 100 38 57 14 38 262 310 2137

40 70 21 46 8 32 221 210 1448 80 27 50 10 32 221 255 1758 90 32 57 14 37 255 305 2103 100 38 63 17 44 303 345 2379

50 70 21 48 9 32 221 225 1551 80 27 53 12 34 234 270 1862 90 32 60 16 41 283 325 2241 100 38 69 21 49 338 380 2620

60 70 21 50 10 32 221 240 1655 80 27 56 13 37 255 290 2000 90 32 63 17 44 303 340 2344 100 38 75 24 55 379 395 2724

70 70 21 52 11 32 221 255 1758 80 27 59 15 40 276 305 2103 90 32 67 19 48 331 355 2448

80 70 21 53 12 36 248 270 1862 80 27 62 17 43 296 320 2206 90 32 70 21 42 356 370 2551

90 70 21 55 13 40 276 285 1965 80 27 65 18 47 324 335 2310

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.