thanks for the info, unfortuneately im not a gm tech so i really have no idea what or where the parts are that are mentioned....ill check my repair manual and see what i can do, although it seems this should be something that gm should cover warranty or not.
Check with your dealer, there was a campaign to upgrading the wire harness and they can look up from your VIN number if your Sierra has the upgraded wire harness. You can also pick up the parts from Auto Zone and they have the step by step instructions to replacing the blower resistor with common tools.
Here is a link that should help you understand what your issue your HVAC is having.
http://www.motorcity1.com/
Replace the blower motor resistor and module connector using the following procedure:
Remove the blower fuse.
• Fullsize Trucks and Utility Vehicles -- Htr A/C & HVAC 1 fuses
• Midsize Utility Vehicles -- Blower Fuse 35 located in the Underhood Fuse Block
1. Lower the hush panel (under the glove box) or close-out panel enough to gain access to the resistor module connector.
2. Disconnect the connector from the resistor module and remove the tape from the wiring harness to expose the wiring.
3. Cut the wires back far enough from the connector to eliminate any melted insulation on the wire.
Tip
Use the old connector as a map for splicing the wires for the new connector. Be sure to use the correct crimping tool. Use only Duraseal splice sleeves. Other splice sleeves may not protect the splice from moisture or provide a good electrical connection.
4. Install the new connector. Use the yellow splice sleeves provided with the connector.
5. Install new blower motor resistor.
6. Reinstall the fuse or connector block. Test the blower motor to make sure all speeds are functional.
7. Reinstall the hush panel/close-out panel.
This take about 40 min to do from start to finish including clean up time, then enjoy the extra money your saved from doing the job your self.
http://www.gmfullsize.com/forum/showthread.php?t=177092
