My AC air distruibution does not function properly I beleive it has failed and is now in the default setting which foggs up my windscreen. No air comes out of the center vent only the windshield defogger vents and the side vents.

I think there must be a vacuum leak or complete loss of vacum in the system, or maybe not. The central locks work ( i believe they are vacuum actuated as well) I didn't check the cruise control as yet ( but I am certain that uses vaccum to oporate as well). The gas cap door lock still works.

My question is. Where is the Vaccum reservoir tank? Could that be the problem or is it just the vacuum motors controlling the flaps in the dash that is defective. Could it be as simple as a vaccum line being disconnected somewhere? Where should I check first?

I just bought this mecedes and don't have the shop manual as yet so I don't know where things are or what procedures are involved in removing the center console and dash.

I see what looks like a disconnected vacuum line in the trunk under the carpet in the spare tire wheel well but I don't see what it is supposed to be connected to. On my Audi & VW the vacuum reservoir is in the front fender drivers side

Any help would be appreciated

On my Audi & VW the vacuum reservoir is in the front fender drivers side

Under the hood on the right side of the vehicle just below the windshield area you will find a number of colored plastic vacuum lines. These lines will either make a connection to a distribution block and the reservoir OR they will connect directly to the vehicles interior and the reservoir. If you have a distribution block it may be cracked, with the engine running listen closely with your ear and you may hear it hissing.

Without a distibution block run the engine with the AC system on, open the trunk and listen on the right side. If you hear something cycling on and off, you definitely have a system leak. If you do not hear the vacuum pressure pump cycling then the pump may be a contributing cause to your AC problem.

Try starting with these few items then let us know what you discover

and I'll send you a diagram of the entire vacuum system.

Hello CLK320MIA, I'm having the same problem with my w202 and would really appreciate if you could also send me the diagram of the vacuum system. Thanks in advance. BTW, my e-mail address is w.ong@ifad.org.