The temperature control knob and the speed adjustment work fine but the selector switch doesn't. The one where you choose vent or floor or whatever. It will only blow out of the defroster no matter what setting you turn it to. I pulled the dash and found a red, white, blue and yellow set of wires coming from the back of the switch. (vaccum lines?)The yellow one goes to a silver cylinder right there behind the radio. But it had come disconnected. So I hooked it up and tried the system and IT WORKED!! Hooray right? Then once I tested all the selections I switched it to defroster again, to make sure that still worked. It did but when I went back to floor or vent or anything it just kept blowing out the defroster. I disconnected and reconnected that yellow wire but no go. What does all this mean? I'm baffled.