My 2002 blazer makes a whistle noise from front end I can't pin point what it is if I take off belt it stops I've changed a.c. compressor alternator tensioner pulley pretty much but power steering pump I cut figure out what it is I have no signs of bad power steering pump no other sounds

 

Did you change the belt itself? Also, it could be the water pump. You didn't mention that you changed it.

 

Grab the pulley, slide off the serpentine belt. Check if there's anything loose, one by one. Inspect the inner shroud space. Check if the fan mount is not broken (a metal plate where the bolts come in).