Just purchased a few weeks back a 2003 Trailblazer Ext 4wd with 142,000 miles for my soon to be 16 year old son to drive. He loves it and now may have to fight mommy for it. She has been driving it to see if any issues pop up. The only issue we knew up front was that the rear hvac system did not work at all. I did my research here on this forum and was able to get it working correctly. We had to replace the Rear Aux. Climate controller and the Blower Speed Module. Thanking everyone who has made a post or thread on this issue.