marooned

Hi there. I'm having a weird problem with the engine fan in my car. It rarely comes on, but when I first bought it, it seemed to come on pretty much all the time after being driven. My mechanic told me that the engine senses when it is hot and turns itself on, which makes sense. But now that it's hotter shouldn't it be coming on more frequently? The weird part is that occasionally if the key is in the ignition the fan will just stay on... until I pull the key out. What might be going on here? relay maybe? Thanks in advance.

marooned

anybody?