A/C - Compressor Failure During Aggressive Accelerations

File In Section: 01 - HVAC

Bulletin No.: 99-01-38-001

Date: June, 1999

TECHNICAL

Subject:
A/C Compressor Failure During Aggressive Engine Accelerations
(Reprogram PCM)

Models:
1998 Chevrolet Camaro
1998 Pontiac Firebird
with 5.7 L V8 Engine (VIN G - RPO LS1)

Condition
Some customers may comment on an A/C compressor failure during aggressive engine accelerations, due to compressor over-speed.

Cause
The engine calibration is designed for A/C compressor shut-off at high engine speeds to prevent over-speeding the A/C compressor. In the 1998 model year, timer delays in the engine calibration can result in delayed A/C compressor shut-off during aggressive engine accelerations, resulting in A/C compressor over-speed and possible A/C compressor failure.

Correction
When the compressor is replaced on 1998 vehicles with the LS1 engine, reprogram the Powertrain Control Module (PCM) using the new calibrations found on CD # 8 for 1999. This new engine calibration, with reduced timer delays, will provide additional protection against over-speeding of the A/C compressor.

Important:
Do not attempt to order the calibration from GMSPO. The calibration is programmed into the vehicle's PCM via a Techline tool.

Use a Techline terminal or scan tool to program the Powertrain Control Module with the calibration appropriate for the vehicle and perform the learn procedure.

To ensure the Powertrain Control Module programming/RPO configuration, confirm that the following conditions exist in order to prepare for PCM programming:

^ The battery is fully charged.

^ The ignition switch is in the "RUN" position.

^ The Data Link Connector (DLC) is accessible.

^ Refer to the latest Techline terminal and equipment user's instructions

^ Clear the Diagnostic Trouble Codes (DTC's) after the programming is complete.

Warranty information

For vehicles repaired under warranty, use:

Labor Labor
Operation Description Time

J6355 Prom, Reprogramming - On Car 0.4 hr