Ever since I unscrewed my dash to put bulbs into my message center, the air has only been blowing out of the front vents on my 91 D150. Both defroster and heater blow out the front and it’s becoming a real issue with the colder weather as my windshield is fogging up and I have no way to clear it quickly. Anyone know why?

 

Check the vacuum lines going to the control unit.

 

Unfortunately I can’t seem to find any vacuum lines. All I was able to find was a 8 port flat socket unplugged that I can’t seem to find where it leads. If anyone could point me in the direction with a diagram or photos that’d be great