Squeal when blower motor is on?
 

I have been having an issue with my 1985 chevy silverado squealing really loud when i have the blower motor on. It stops when I turn the blower motor off and when the motor gets warmed up. It won't squeal when its at high rpms just when it idles and when I first take off. I can't pin point where it is coming from. I tried belt dressing and it didn't really help much. I haven't looked for any shine to the serpentine belt yet..I will tomorrow. Does anyone have any idea what this could be? Thank

I would think it be the belt most likely

or it could be the bearing in the blower motor. It sounds like its on the way out.