A/C - Excessive Cabin Moisture/Reduced Window Clearing
TECHNICALBulletin No.: 11-01-38-001B
Date: July 20, 2011
Subject: Excessive Cabin Moisture / Reduced Window Clearing, Non Responsive HVAC Control (Reprogram HVAC System Control Module)
Models:
2010-2011 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2010-2011 GMC Sierra, Yukon, Yukon XL, Yukon Denali, Yukon Denali XL
All with Manual Air Conditioning (RPO CJ3 or C67)
Vehicles Built Prior to March 14, 2011
Supercede:
This bulletin is being revised to add build date information. Please discard Corporate Bulletin Number 11-01-38-001A (Section 01 - HVAC).
Condition #1
In rare cases, some customers may comment of excessive cabin moisture or difficulty keeping the windows clear in low ambient temperatures.
Cause #1
This concern may be caused by the recirculation door being in the recirculation position while the mode is set to a floor through defrost position.
Condition #2
Some customers may comment that the HVAC temperature or mode does not change to the current HVAC control setting at start up. If the HVAC temperature or mode controls are changed, then the doors will move to the correct position. There will be no DTCs set.
Cause #2
This condition may be caused by changing the HVAC temperature or mode controls while the ignition key is turned off or immediately before turning the key off.
Correction for Condition #1 and #2
Important
DO NOT replace the HVAC control module for this concern.
Revised software has been developed to address both conditions.
Technicians are to reprogram the HVAC control module using the Service Programming System (SPS) with the latest software currently available in TIS2WEB.
When using a Tech 2(R) or a Multiple Diagnostic Interface (MDI) for reprogramming, ensure that it is updated with the latest software version.
During programming, the battery voltage must be maintained within the proper range of 12-15 Volts. Only use the approved Midtronics(R) PSC 550 Battery Maintainer (SPS Programming Support Tool EL-49642) or equivalent during programming.
Warranty Information
For vehicles repaired under warranty, use the table.
Disclaimer