1982 300D turbo. My center vent just stopped working. The defroster no longer blowers hot air up on the windows, it blows on the side vents. Please Help. I live in Sacramento and it is hot.

Most likely a vacuum leak in your AC system. The opening and closing of the vents is controlled by vacuum. Try running a search with the words "AC," "vacuum," "vent," and "center" variously arranged. If it is blowing hot air all the time I believe this is either a problem with the AC servo unit (the actual controller with the buttons you control the AC through) or with the monovalve, but once again, a search should give you more definite answers since so many people have AC problems.

__________________
"I would rather be ashes than dust!
I would rather that my spark should burn out in a brillaint blaze
than it should be stifled by dryrot.
I would rather be a superb meteor,
every atom of me in magnificent glow,
than a sleepy and permanent planet.
The proper function of man is to live, not to exist.
I shall not waste my days in trying to prolong them.
I shall use my time."

-Jack London 1876-1916

1983 300CDT (running WVO since 12/05)
1981 300SD (parts car)

If you are getting no air through the center vents when the a/c is on, then, the center vent vacuum pod may have ruptured. The same thing happened to me last summer. I rigged the center vent so that it would stay open all the time, then I could regulate the flow through the center vents with the regulators that are located in the middle of each of the center vents. There should be plenty of hits available to you by searching. "center vents" or the like. A systematic diagnosis of the vacuum system is probably in order, though. If you are getting nothing through the defroster vent either, then it may be the ACC control just like 83Mercedes has said.

It's all just a dream, babe,
A vacuum, a scheme, babe,
That sucks you into feelin' like this. To Ramona: Bob Dylan


Good luck,
Tom

__________________
1993 300TE
1984 300D
1984 300SD
1976 BMW R90S

Thank you, for your quick response. This is my first diesel. I know my way around gas engine. But this car is backwards (so to speak) from a gas .

MB gassers have the same ACC system. This problem has nothing to do with the engine or what it runs on

What do you mean that the defroster no longer blows hot air on the windows? Are you saying that happens in AC mode (black up arrow, white down arrow)? If so you have two separate problems; getting air of the right temperature and getting it to blow through the correct registers.

Before you replace the center vent vacuum pod, check if the other ACC modes work. If only defrost works, the problem could be the vacuum source for the ACC system.

Sixto
95 S420
87 300SDL