The cooling fan runs all the time?

The cooling fan runs all the time from the time you start the engine until you turn it off. When I first bought the car the fan didn't run but the heater and stereo didn't work now while installing the stereo I found the constant hot under dash and it appeared to be missing a wire that had been connected befor and the was a loose red wire hanging si I hooked it up and heater started to work but fan came on as well. So i'm pretty sure that the wiring for the fan motor isn't correct or something of that nature but i'm not sure what it should look like under there so I don't know can you please help me with a wiring diagram or somthing hell even a picture would work