Basically is I am idling and I have the heat on and I do it NJ and it's always cold out and I hear a squeaking noise sounds like metal on metal. If I hit the gas until about 15-20 MPH it gets really loud. It will stop if I turn it to A/C or if I turn on the defoggers only when I put it on face/feet it will start up again. I have adjusted the belt about 5 time from really lose to as tight as humanly possible nothing and I have a brand new Dayco belt on. Was making the same noise with the old belt which was a Gates.

 

Mine too. Haven't got into it yet,but have an idea.[ alternator bearing] When the elec. fan cycles, the extra load makes worn bearing squeal. Mine does it when fan cycles & more when head lights are on. If you figure it out, post results.