Rubbing noise when I turn left at low speeds?

Hey everyone, I am new to this forum. I have a 98 mustang v6 auto and recently have developed a whinnying/rubbing noise when I turn left at low speeds (less then 10 mph or so) Yesterday the car was in parked, I opened the hood and started turning the wheel and the noise started again without the car not even moving. The noise seems to be coming from where you put power steering fluid in. Does anyone happen to know what this may be? Thanks for any help guys!

thanks for the reply! The fluid is full and the belt doesn't look bad...just to be safe I put some belt dressing on it and nothing changed. The system has never been worked on. I guess I will look for that additive and see if anything changes. thanks again