I have a 1988 ford f-150 and there is a very loud squeaking noise on in the morning when I first start it up or on day that are very foggy or raining. I was thinking it was the belt but the tension is corrct to the book. What else could it be? a pulley? Please help me it is gettin very annoyying.

 

if it mainly happens during foggy/rainy days when first started, it's probably the belt. i think the belt is slightly glazed, and the moisture is making it squeal
eden