I have a problem with a vacuum leak on my 1994 c280. I have read all the threads on this and they have been very helpful. I suspect the leak is in one of the actuators behind the dash for the ac system or air diversion flaps. My question is can anybody tell me where I can get a good diagram for all the vacuum lines and colours . I have account with alldata but they dont seem very clear on there. Is the cd out for the w202 yet? If so are the diagrams any good on it and where can I get one?


Thanks for any help.

does anybody have the diagram?

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1994 C280
2009 VW Tiguan
1993 Toyota X-tra Cab SE-5


1973 220D ... Gone, but not forgotten
1991 Alfa Romeo 164L Gone, wife MADE me forget it

2006 Hyundai Tucson... just straight out FORGOTTEN!

This is a perennial problem. Somebody could make a dollar or two publishing diagrams of just the vacuum systems in different models. Some are available and some aren't, and it seems like the ones that are available are always partial or mixed up with other things. If some diligent mechanic would make the diagrams they could sell books, ebooks, access to a web site, or whatever and make their boat payments.

I've wished before that I had the lore to do this myself, but unfortunately I'm a prospective customer for such a thing, not a producer of it.

Here is the vacuum diagram. the fresh air flap is circled!

Attached Files

W202 ac vacuum.pdf (62.3 KB, 633 views)

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MERCEDES Benz Master Guild Technician (6 TIMES)
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MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
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You are the man. I'm tackling this tonight. If I disconnect the vac tubes (plug them) then will the flap stay in the position it is in, default to a set position, or just blow in the wind on a free hinge?

I am supposing that, while I may be able to access the vac block behind the glove compartment that I can't get all the way to the flap without pulling the dash -- correct?

Last question: What happens to the A/C system if I just pull the fuse on that entire assist pump?

Thank you very much.

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1994 C280, dark green metallic
105k miles

1991 190E 2.6, Black
191,500 miles
(sold to another forum member)

2003 Chevy Tahoe LT, Redfire Metallic
105k miles

1989 Mustang GT Cobra Convertible
43k miles

I had the exact same problem, air would stop blowing from center vent when I pressed on the accelerator. How I know how to fix it, Happy Again
Remove the glove box, 2 screws at the top edge next to the latch. 2 on the bottom, sometimes they are cover with a plug, they are right where the felt part of the glove box starts and about 1 1/2" from the left and right edge of the box.
Pull down on the top of the box and outward, it will pop out,
!!! UNPLUG THE GLOVE BOX LIGHT BEFORE YOU PULL IT TO FAR !!!
You should be able to see the top of the Switchover Valve Block (SVB), at the top there is a Green line. Right in front of it is a black tube connecting the right vent and the center vent air (so air can flow to the right side vent). Push it to the left hard and remove it from the right vent connector. Now you should be able to see the whole SVB. On the #2 hose (Marron or Dark Red- solid color) you want to clamp that line off. I used a bent washer, fold the washer, place the line in the fold and clamp it shut with a pair of Vise-Grips. I used two, just to make sure. NOW THE AIR CONTINUES TO BLOW OUT THE CENTER VENT.
This may effect your defroster, I used the switch to change air flow and I am getting some air to the Defrost vent when I have it in the ARROW UP position.
Use the AUTO air and you will have air flow regardless of pressing on the accelerator.
You you would like to test this concept first, just put a pair of Vise-Grips on the Maroon (clamp it closed) and give it a test drive. Then you can work on clamping it off with the washer method I used or whatever you can think of.