Probably a bad vac servo for floor heat. The flap can stick "between" AC and floor, so you don't get any heat on the floor. Check the defrost vents, too -- if you have lots of air there, its a servo.

There are several -- see other postings.

The little foam tube is for the air temp sensor -- if it is bad, you get strange temp control -- teh 300TE is currently oscillating between too hot and too cold, and it isn't sucking in air at the temp sensor grille (beside the courtesy lamp in this car).

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!