Whenever it's really cold, or really wet outside, my car makes a loud screeching sound... I've heard different advices - serpentine belt (most believable), calipers rotors or pads, also stress on the pulleys....

So, this sound activates for MANY crazy things - I start up the car, and when I switch on the lights, it'll start! I know, crazy! ... If it's really cold or wet, it'll start and stop with turning the heat on or off... If I turn sharply, it happens... Sometimes it happens randomly. Sometimes, it's screeches REALLY loud for like 400 ft (at the most)... It mainly happens with the heat on I notice.

So if it is the serpentine, will I possibly have to change the pulleys as well as the belt(s)?? Cuz this seems to be the first and the cheapest stop I should make for the car.