I picked up a used eletric fan today that we had laying around work, to see if it would work on my 5.0. I think it came off a crown vic or grand marques, any way my question is, there is a box attached to the fan that the wires run through, what does the box do? There are three wires going into box, red and black 12g and a green 16g wire. Then a red and black go from box to the fan. I was wondering if this was a controller or what, thanks for any help.