Adm Msg - 2002 and 2003 TrailBlazer, Envoy and Bravada - Intermittent Poor Performing or No Air Conditioning Admin Number VSS 20020128 9/26/02

Some 2002-2003 Chevrolet TrailBlazer, GMC Envoy and Oldsmobile Bravada vehicles may exhibit a condition of no cold air from the air conditioning or poor performance of the air conditioning system. This concern may occur at any time during the drive cycle and at any temperature setting. The HVAC system operation may return to normal after the vehicle has been keyed to off and restarted. This concern has been found on vehicles equipped with both manual (CJ3) and automatic (CJ2) HVAC systems.

To ensure customer satisfaction and prevent service visits, the HVAC system should be enhanced with a software updated, especially in those areas with high ambient temperatures and high humidity. The HVAC control module in any vehicle built prior to October, 2002 should be updated using software available through GM Access beginning September 9, 2002. The update will be available October 7, 2002 on TIS 2000 CD version 10. This software update addresses both the intermittent and no cooling on all systems and the poor performance concerns on automatic systems (CJ2). If the software update does not correct the concerns, perform the HVAC Diagnostic System Check and repair as necessary. If an HVAC control module is replaced with a part from GMSPO, make sure the module has this latest software update. The module may need to be updated even though it is a new part.

The above information comes from Corporate Bulletin Number 02-01-39-005 which will soon be published.

For vehicles repaired under warranty, use: