Blower Motor/need Help!!!

[IAMTHEROCK]

I Have A 2000 F250 Sd. I Only Have High Speed From The Blower. I'm An Old School Mechanic. Back Then It Was The Resistor Bank Or The Switch. I Changed Them Both And Still Have No Lower Speeds. I Can't Find A Wireing Diagram For This App. I Read Somewhere About A Fusible Link. Is There A Relay For The Lower Speeds? Any Help Would Be Appreciated.