Battery went dead on my 99 Jimmy with auto HVAC. Now, after I got it jumped, the blend door cycled from cold to hot on the drive back home and then stuck to heat all the time. There's a noise coming from behind the dash, starts as a scraping, then turns into a squeeking, then pops and goes away for a few seconds before it's back. The modes work fine, and the noise is continuing now even though heat is stuck on full bore. I've had no luck at ALL trying to find any kind of troubleshooting book, and as we all know, Haynes manuals are crap. So, short of my buying $125 worth of factory service manuals, anyone know where I can get some troubleshooting steps, or maybe you've run into this before?