INSUFFICIENT A/C COOLING WHILE DRIVING-REPLACE MEM-CAL

*VEHICLES AFFECTED: 1988-89 B AND D CARLINES WITH 5.0L (VIN Y)

Some 1988-1989 Broughams may experience a condition of insufficient A/C cooling while driving in stop-and-go traffic in hot, humid climates. This condition may be caused by the ECM PROM calibration. The production calibration disengages the A/C compressor clutch with changes in throttle angle, instead of only during a wide open throttle maneuver (as in past model years).

Should the insufficient A/C cooling only occur at an extended idle, refer to Product Service Bulletin 88-1-132.

To repair this condition:

1. Verify that the A/C system has the proper charge of Refrigerant 12. With ambient temperature above 15 DEG C (60 DEG F):

Start engine and allow to warm up.

Open hood and body doors.

Set CCP at 15 DEG C (60 DEG F) and "auto" setting.

"Hand feel" the temperature of the evaporator inlet pipe after the orifice tube and'accumulator surface with the compressor engaged.

The temperature of both should be the same and both should be the same degree cooler than the ambient temperature.

If not, refer to Section 1C of the Service Information Manual for diagnosis.

2. Install a scan tool and record the ECM PROM I.D. If the ECM PROM I.D. is 7524 (Federal) or 7528 (California), install the revised ECM PROM from the chart below: Emission Service Year System MEM-CAL P/N ---- ------ ----------- 1988-1989 Federal 16122177 1988-1989 California 16132056

3. If the condition is still present after installing the MEM-CAL, refer to ECC Functional Test in Section 1C of the 1988 or 1989 Service Information Manual.

Use most applicable Labour operation from the Canadian Labour Time guide.

1988-1989 "B" carlines with 5.OL (VIN Code Y) Engine A condition of insufficient A/C cooling during light throttle (5% TPS) acceleration may be the result of the A/C compressor being disengaged momentarily as the throttle is being depressed. This is the result of the prom calibration.

Should comments be received of this condition and the A/C refrigerant system is functioning properly, you may need to install a new service prom listed below.

There was a running change made in the 1989 model year to eliminate this feature. Use scan tool to verify Prom I.D. before ordering parts.

Scan Tool Broadcast Model Emissions New Service Prom PROM I.D. Code ----- --------- ---------------- --------- ---- B Federal 16122177 5833 ALUP

Warranty Information

Use applicable Labour operation. Labour time .4 hours.

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.