Actually, after my car got out of the shop from the wreck, I had the same problem. The fvcking shop didn't tighten down my PS pulley or the AC pulley.

I got out of the lot, drive 1/2 mile and my power steering went. I go back and they fixed it real quick. I start driving home (30 min drive) and I kick my AC on while driving on the highway, and hear this NASTY noise.

I went right to my friend's house, he has a garage & tools, I don't. He looked it all over and saw that my AC pulley was VERY loose. He tightened it down, and everything is great

Hope this helps.