PLEASE HELP!!!!!

I've been experiencing this annoying clicking/scratching sound for quite a while, but I kept on thinking that it would go away. It happens when I have the car either in reverse or drive, while stepping on the brakes or at low speeds, with the A/C on and I steer either to the right or left. I've brought it to the dealer and they said it was the throttle problem, but I've listened to the sound myself and had my dad check it out. He noticed that everytime that the sound occurs, the inner pulley on the A/C pulley sticks for a second and then runs again. He checked to see if it was a lose of current but it wasn't. I've heard that it was an electronic clutch that clings on like a magnet but I don't know why it's making this sound. Please help b/c it makes me so embarrassed to turn into a parking space and then this loud scratchy occurs and catches everyone's attention! I'm a picky Lexus freak and every little rattaling sound bothers me!

 

Take it to Lexus,, They should warrenty it for you...
Good Luck

 

Thanks for replying back, but I already brought it up to them and they want to charge me $1100 to change out the throttle, which I doubt is the cause of the problem. My car's still under the three years term, but over the 50k warranty. Ever since I've brought it back from the dealer, the sound isn't as loud as before, but it is still happening. I've had this problem a while back before, and I remember it wasn't the throttle, but I can't remember what it was. Uggg....Could it be one of the clutches? Any help is greatly appreciated!