1998 Blazer, 4-door, 4x4

When I first bought this thing, the owner told me that one of the actuators had broke or had a bad leak, I can’t remember exactly. Anyway, he removed it, plugged the vacuum lines, and tied the blend door back so it wouldn’t just be flapping around. Sourced a “new” one from a junk yard and put it in and hooked up the vacuum lines. Then weird issues started happening.

I want to start by saying I did test each setting and they all held vacuum for acceptable amount of time. And I didn’t see any signs that the vacuum lines were contaminated with ATF from the transfer case. (The transfer case was over full when I changed the fluid. I’m guessing the output shaft seal has failed, but that’s an issue for another day…)

Now to the problems..
-When I have the **** set to Max AC, cold air blows through the dash vents and floor vents. (Max AC should only blow through the dash vents, right?) And if I turn the fan speed up to 4, it closes the dash vents and goes 100% to the floor vents.
-In basically all other settings the floor vents always blow air
-If on any setting and I turn the heat on it’s hit or miss if it’ll actually blow hot air. Seems like it’s more likely to blow hot air if I have the fan speed set to 3 or lower.

All the actuators move when I change setting, just not working properly and I have no idea where to go. I’ve followed other forums and diagnosed based on their advice and everything checks out, however it is not working properly.

Thanks in advance for any help!