01 Blazer Blower motor connections..

What is your question?

I have an 01 Blazer and the blower motor needs to be replaced but the connections on the blower motor itself there's two wires in the electrical connection there's a third one outside of it which is separate that comes out of the resistor I need to know what that third brown wire is and why I can't find the blower motor to match up with that electrical setup all the new ones only have two wires not three.. Ut is an auto climate control not manual if that helps.. a few places told me I had to buy them together the resistor and the blower mower but that sounded crazy to me.. any ideas would be greatly appreciated..