mkwired

I have a 98 Legacy and one of the fans on my radiator doesn't turn off even when the engine is cool or in Accesory mode. It will only stop running when all the power is turned off to the car. I was working on my stereo last week for a couple hours and even after 2 hours it was still going, still draining my battery... Now I just disconnect the fan when I am working but I'd really like to try and fix this problem. I think it might be a temp. sensor but I'm not sure? any ideas? anyone had this problem?