Everytime I turn my A/C on my car makes a screehing/squealing noise. It sounds horrible and is very loud. I turn my A/C on and off about 3 time and then it stops. But it usually comes back on again when I shift, but only when the air is on. It also makes the sound if I turn my wheel too far, for example when I'm doing U-turns. My friend told me I should put something called belt dressing on it but my other friend said it would just make things worse and put off the innevitable, which she said was getting some belt replaced. Any help please?