Hello I am trying to replace a bathroom exhaust fan/light. The old one was taken down a few months ago and I can't remember how the wires were connected (I know, I should have written it down). The new unit is a fan and a light. I have two switches on the wall one to turn the fan on and one for the light. The Fan/light unit only has 3 wires coming out of it: black, white , and green. But the line in the attic going to the unit has 4 wires: copper, black, red, brown. I know that the green wire is the ground and connects to the copper wire. But I don't know how to hook up the rest. Can anyone help me? will this require me to call an electrician? The house was built in late 70's if that helps. Thank you for any help you have for me.