Second update: re-looking at your photos...you need a new heater control assembly, for sure. : o ) First, that rightmost cable, the airflow control cable, seems unsecured (as I think you noted). I am almost positive you need to secure that for the airflow lever arm to properly extend/retract the cable...which almost certainly accounts for why you always have air to the vents and very little air to the defroster vents...you move the airflow lever but do not actually extend/retract the cable properly...thus the vented air when you think you have selected DEFROSTER...because the cable does not get extended all the way, you likely just shove the cable assembly around instead of extending the cable and moving the white circular cam on the passenger side of the heater box. Second, it probably does not matter, but are you sure the vacuum line connector goes with that gold clip? On my old heater control assembly, it seems like I have a switch in that spot, and the vacuum connector sits at the very rear of the heater control assembly. The switch closes a circuit when the arm moves into the DEFROSTER position. Due to the state of the heater control assembly, I am not sure if you lack the switch due to damage to the heater control assembly or because you do not have AC. * Note: the pic above has a broken black plastic peg, which should go into the hole in the brassy metal arm, but got sheared off...linking for illustration only.