Rattling sound coming from steering column..

[coldfire204]

Hello, got a question regarding my '01 Explorer.. this morning I got in and turned the car on, when idling I noticed a buzzing sound coming from the steering column when I turned the wheel to back out of my parking space. I killed the radio rolled down the window and listened as I backed out I could hear a rattling noise coming from underneath the hood. It seemed to fade as I accelerated. I let the car warm up, gave the wheel a couple turns, turned it off and checked the power steering fluid. There is no min max reading available but from the looks of the reservoir it seemed fine. Is this a sign of something more serious that I'll have to repair? Any advice is appreciated, thanks! Side note, there is also rattling when I run the AC, but I'm not as worried about that as I am the steering issue.