The line supplying vac for the doors go through the firewall on the
drivers side, works it's way under the dash, into the left side of the
driver footwell area and then goes into the drivers door via the hinge
area of the door.    I think there should be at least 2 or 3 lines
there, one to bring vac from engine pump, others to run to other
doors.  When you turn the key in driver's door, it opens driver door
and moves what they call a vac switch which is connected to drivers
lock and which then applies vac to other doors to lock/unlock  them.

Since he has lines disconnected in engine compartment, instead of
taking door apart, he can probably start by tracing color coded lines
back from door hinge area to find the one that should be vac source
and make sure it's connected in engine compartment and has vac.

Of course, since someone disconnected major parts of the vac system
and plugged it off, it's likely there are leaks somewhere.  In the
case of my vac lines, the failure point for my 2 problems was in the
area where the vac lines go through the rubber grommet at the driver
firewall.  I had both the ignition shut off and door vac lines break
at that point.   Just wiggling them a bit they can right apart at that
point.