Fix the vacuum supply problem. Most likely the transducers for the EGR and air recirc valve are busted and leaking, and the way that system is set up, you won't have enough vac for proper transmission control or ACC.

There is a 5-way T connector at the front of the engine. Check it for integrity, then use a MitiVac to check that all four branches hold vac. If the two on the passenger side do not, you have busted transducers, and can just plug the lines (I did this about 100,000 miles ago) or replace the transducers if you want the EGR and air recirc valve to work.

You can trace the line to the ACC, it goes into the passenger compartment near the brake booster. Check it, it must hold vac unless it is switching modes. Likely there isn't enough vac due to a leak or broken line, easily fixed.

That will restore both tranny control and ACC operation. Note that the dash center vents are ONLY open for high cooling, they close while the side vents still blow cold air.

Peter

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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!