I know that it's fairly common to not have air coming out from the center vents. But in my case, air ONLY comes out from EVERY vent except the center ones, but under every pushbutton setting! Defrost, Bi-Level, etc. The car is a 1982 300D turbo with the late model climate control (Temperature wheel and 5 horizontal buttons).

The pink vent dampers do receive vacuum and do hold it. I just don't know what's up with them. The pushbutton unit has been rebuilt, so I doubt that's the problem. Thanks for any advice.

I have owned an 82 300d for 15 years. the acucator behind the glove box controls the center vents. Its purpost is to divert the air from the center vents to the defroster. Except when on defrost, you should get air from the center vents. Remove the Glove box liner. You will spot the accuator. With the car running, press defrost and then the buttons for the A/C If it is working, you should see the accucator move. It should move full range. If not check the accucator with a vacume pump.
Good luck,
Hal
82 300d 193k

Loss of vacuum in the system or to the vacuum switch-over valves will cause this problem. You need to check the vacuum supply behind the push-button control unit.

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Greetings Speedy,

Are you saying that you get no air flow at all out of the center vents, even in the totally cool mode of the temp wheel? Actually, this is the only time you should be getting air flow from these vents. Any cool air flowing from any vents at all in the cool temp mode on the temp wheel? If the rest of the vents are only producing warm air out the side and floor vents, there may be another problem. please elaborate on air temps and where you can get it from.

Charles

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"Tell me and I will listen, Teach me and I will learn, Show me and I will accomplish, Involve me and I will succeed."
'84 300SD 256,000 Gold on Brown (Mileage Award)
'86 300E 246,000 Blue on Tan

The AC compressor has frozen up, so I cut the belt that drives it. For now I will live without AC, since I'm using heat in the mornings anyway. Air comes out of the side vents, defrost vents, and footwell vents, regardless of the pushbutton or temperature setting.

Greetings Speedy,

Let run down the list as to how your system is suppose to operate compared to how it is operating now, so you can note where it's not doing it's job correctly.
First off the climate control push button unit not only operates various vacuum valves to direct air flow out specific vents, but the temp wheel also controls where the flow of air will go depending on your temp. choice. Let's run through the economy mode first first, seeing as it simulates most valve actions in relation to temp. wheel settings. Choose auto fan mode, and turn temp wheel to max heat detent. Air should flow out of the side vents and the floor board, and a slight flow to the defrost vents. Turning the temp wheel to max cool should cause air to stop flowing to the footwell but will flow from the center and side vents and fan speed will increase. In a defrost push button mode, you should get full heat to the defrost vents and side vents but flow to the footwell will end. I know there are two more modes to go through, but if at this point, you are not getting these reactions from your climate control, let's compare notes now. If you send me your email address I can send you a troubleshooting article for this system, and how it should react.

Charles

__________________
"Tell me and I will listen, Teach me and I will learn, Show me and I will accomplish, Involve me and I will succeed."
'84 300SD 256,000 Gold on Brown (Mileage Award)
'86 300E 246,000 Blue on Tan