CTS V6-3.2L VIN N (2003)
Control Module HVAC: Customer Interest
A/C - Limited Control of Defroster Temperature
Bulletin No.: 04-01-39-008
Date: June 24, 2004
TECHNICAL
Subject:
Limited Ability to Control Windshield Defroster Temperature (Update HVAC Control Module Software)
Models:
2003 Cadillac CTS
Built From July 2002 to End of 2003 Model Year
Condition
Some customers may comment on a limited ability to control the windshield defroster temperature. The usual concern is that the windshield defroster
outlet temperature is too hot.
Cause
A software change was made in July 2002 to limit the temperature regulation for the defrost outlet to no less than 70% full heat. This was done to reduce
conditions of fogging on the outside of the windshield in the summer and snow sticking to the windshield in the winter.
Correction
A change was made to the HVAC (heating, ventilation and air conditioning) control module software beginning with the 2004 model year that allows
more adjustment range based upon the outside ambient temperature. This new HVAC control module software is now available for customers that may
object to the windshield defroster operation. This software update also includes enhancements such as reducing heat during vent mode with the air
conditioning off and reducing the blower motor speed during OnStar(R) communications (to limit noise inputs during a call).
Technicians are to reprogram the HVAC control module with an updated software calibration. The new calibration will be released beginning with TIS
satellite data update version 5.5, available May 10, 2004.
Warranty Information
For vehicles repaired under warranty, use the table.
Disclaimer