Yet another climate control system question

[kernelpanic]

Sorry if I ask questions that have been have been discussed before.
I have spent some time looking over old posts, but see mostly newer systems than mine.
I have a 77 300D non turbo. Witch if I understand correctly is the 1st year for ACC system. ??

I wonder if someone could point me in the right direction in finding a vac diagram or any advice as to where start diagnosing this older system? I have only owned this car since last fall, just in time to put it to bed for the winter. So have little time to drive it or spend much time looking it over.

What I know so far …. Defrost has super hot uncontrollable heat. Bi-level has super hot uncontrollable heat. Both have no fan control, high only. Temp wheel seems to do nothing.
When I change to “auto high” heat will come out lower foot vents for aprox 10-15 sec then shut down. Change back to bi-level and it will restart. Change to “auto-low” same thing. Will run on low fan for a few sec’s and stop.

The electric coolant pump does not work and is unplugged for now.
I removed the under dash cover on the right side to find 3 vac hoses not connected to anything and one caped off. 1 of the 2 vac pulls that I can see is capped off (far right upper one capped)
I un-caped the one hose, then the bi-level would fail just like the high and low does after a few sec’s.

Have never been able to get air (hot or cold) to come out of the center vents. The 2 side vents work with bi-level. The AC compressor seems to work when the dash switch is turned on. Also compressor cycles when the defrost or bi-level is on. This is about the only things that seem to be working normally.

Sorry for the long post, just want to try to give as much info as I can.

Thanks for any help

Bruce