Ac & Defroster Not Functioning - Flashing Light

[800x]

having exact same problems with 2011 sierra with manual climate controls. please post any info that may help

[RockySierra]

Take to dealership and start a record on it. There might be a software update available to address the issue?

[MikeNH]

The compressor won't run if it's below freezing so until things get hot the defroster won't work great, especially if there's lots of moisture in the cabin, which there will be almost always (warm person(s) breathing in the cold cab). Sounds normal to me.

[800x]

thanks! I will do that.

[800x]

wife parks insame garage with no issues, truck was fine last winter.

[gleno97]

I've got the same problem. Windows fogged up all the time so far this winter. I'm fed up, the General can fix it.

[RockySierra]

Better go get a Toyota, they are perfect trucks, you know Sorry your having the issues.

[800x]

took it to dealer last thursday and they installed new program in hvac ecu, so far works awsome. basically the ac compresor was not kicking in with the defrost and wouldn't remove moisture.

[RockySierra]

Glad to hear it! For those of you under warranty with the issue, get it in now and ask them to perform a software update. May want to find the service bulletin number as many of the dealerships will not be aware of that issue and may deny there being such a fix.

[gmtech4]

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

 

 

 

 

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. For example, when the HVAC controls are being moved to the future desired mode or temperature for the next vehicle start or remote start.

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. For example, when the HVAC controls are being moved to the future desired mode or temperature for the next vehicle start or remote start.

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® 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® PSC 550 Battery Maintainer (SPS Programming Support Tool EL-49642) or equivalent during programming.

<a href="http://gsi.xw.gm.com/newsi/showDoc.do?docSyskey=2692049&from=bcpi#N65624">

Warranty Information

 

 

Document ID: 2692049 canada (if it matters ,IDK )