| Subject: | Certain HVAC Control Heads Not Reprogrammable |
| Models: | 2003 Chevrolet TrailBlazer, TrailBlazer EXT |
This bulletin is being issued to alert technicians that a heating, ventilation
and air conditioning (HVAC) control head was used in production vehicles that can
be programmed only one time. The control head was used in vehicles with both manual
(CJ3) and automatic (CJ2) HVAC systems produced between mid October 2002 through early
January 2003.
The HVAC control head used during this period cannot be reprogrammed using TIS 2000.
The HVAC module part numbers as seen on the Tech2® are 15202099, 15202100, 15202101
and 15202102. A message will appear on the TIS 2000 screen with a warning not
to reprogram these part number modules.
If a technician attempts to reprogram this module, the module will lock up and
become totally non-functional. These modules already have an updated calibration to
address the issues mentioned in Corporate Bulletin Number 02-01-39-005. All
HVAC control heads received from GMSPO for service replacement are a different part
number and they are reprogrammable.
