A/C COMPRESSOR OPERATION DURING START - UP

SUBJECT: A/C COMPRESSOR OPERATION DURING START-UP ON VEHICLES EQUIPPED W/3800 TPI (VIN L)

MODELS/YEARS: 1990 - 91 C, W

From start of production to VIN M4301400 1991 Ninety-Eight models equipped with the 3800 T.P.I. (VIN L) engine allow the A/C compressor to engage up to five seconds during each ignition switch cycle whether the A/C mode switch is in the 'ON' or 'OFF' position. This is done to minimize engine RPM flare. A/C compressor engagement during start-up on vehicles that have a sudden loss of refrigerant or have lost all the refrigerant over a period of time may contribute to an A/C compressor failure.

If a technician is servicing the A/C system oh a vehicle built prior to the breakpoint listed, it is recommended that a new calibration mem-cal be installed, in conjunction with the A/C system repairs.

The new calibration will eliminate A/C compressor operation during engine start-up.

The mem-cals are currently available through GMSPO under the following part numbers.

SCANNER ID IF APPLI- AXLE MEM-CAL BROAD- SERVICE YEAR MODEL CATION RATIO INSTALLED CAST PART # ---- ----- ------- -------- --------- ----- -------- 1991 C Fed. F17/2.84 9994 AXDH 16160178 1991 C Calif. F17/2.84 0004 AXDJ 16160173 1991 C Fed. opt. 3.06* 0014 AXDK 16160168 1991 C Calif. opt. 3.06* 0024 AXDL 16160163 1991 C Exp. opt. 3.06* 0034 AXDM 16160158 1990-91 W Fed. All 0044 AXDN 16160153 1990-91 W Calif. All 0054 AXDP 16160148

* Part of Option Package Y56 or V92

IMPORTANT: The new calibration mem-cals are currently being used in production. Verify if this mem-cal is already installed by the scanner I.D.

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.