look into the power steering pump..
those can whine.

 

I read this entire thread and it seems like there are varying opinions on the whining problem. My 03 Trailblazer currently whines at idle and when accelerating. It started during the winter after I moved to a cold climate; however, it is now summer and the whining is worse than ever. Additionally, my "Service Engine Soon" light just came on; when I got AutoZone to run the diagnostic the computer returned the number "P0475" but did not provide any explanation. Does anyone know what that error number means? And what the best way to address the whining is?

 

My trailblazer as whined for what seems like forever. I replaced the idler and tensioner pulley and it still whines also. It seems to do it more when its humid outside and I first start the truck. It seems to go away once its warmed up. Ive about resigned myself to taking into the dealer even though I like to do all my own repair work.

 

After reading this forum and other ones about this whining noise, which I happen to have w/ my 2006 Trailblazer, I concluded that it might be the idler pulley. I went ahead and got it changed. Wow, she is so quiet now that I felt like how I picked her up from the dealer as brand new 3 yrs ago.

 

I had the same wine maybe a year after I got my 2005 trailblazer took to dealership and they said they replaces the fan clutch and it was a common problem. I have a wine again now sounds like its coming from alternator so I will try to change the idler pully after reading some of the post.

 

take the belt off and spin all the puleys and see which one hes a lot of resistance or slop, or if the beariongs insid squeel