The AC problem is probably vacuum related, the flaps are moved by vac.
Start checking vacuum lines in the engine compartment -- the green plastic lines are for the climate control. You will find that the rubber hose parts that connect the plastic lines are all shot unless replaced recently.
Have a care with the plastic tubes, they will be brittle by now.
Try applying a vacuum to the green line and see if the climate control then works properly -- the fan is switched off if there is no vac in the system.
A large vac leak can make the engine run lean, causing overheating, but I'd bet on a clogged radiator myself, given the age.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!