Ok - not sure how to describe this.... But, when I am at a stoplight at idle and it seems that the fan goes onto cool the engine, it kicks in with this sound vibration....like a card in the spokes of a wheel....d d d d d d d d d d d.....The car itself doesn't feel like it's vibrating, it just sounds like it's vibrating. This started last year and would only do it for little periods at a time or if I moved the car a little it would stop and that would be it. Now - it just does it everytime I'm stopped at a light and it is loud. It doesn't seem to do this as much if I'm just in park though it has done it and I've stepped outside to see if I can heart it....nothing. Also - my lights seem to deem a little when this particular fan or whatever it is turns on. I'm thinking I need to check my battery cables to see how clean they are. Any thoughts on this noise? It's starting to drive me bonkers because it's so loud.