A.C. Vents not working

[Abuimad]

the Middle Ac Vents are not working...no air is comming out at all...what can be the problem ?
also when the AC is off..i can still feel some air comming in from the vents..how can i fix this...

[Pablo7]

thats a common problem with the vacum lines. yo can try opening from the valve, so that way you`ll have the center vents working all the time and you can close it with the round thing in the middle of the vents when you dont want air to come from there.

[202rules]

You know, I noticed air coming out of the vents even when I don't have anything turned on, while just driving. It started happening about a month ago.

Today I tried to see if my center vents work and they don't!!!

I think we have the same problem.

[Abuimad]

Originally posted by 202rules
You know, I noticed air coming out of the vents even when I don't have anything turned on, while just driving. It started happening about a month ago.

Today I tried to see if my center vents work and they don't!!!

I think we have the same problem.

we definetly do....
ill try to fix it this week...but whoever finds the solution first..post up

[htfan1]

If it is vacuum leak related, you should hear some excessive vacuum pump noise coming from the passenger side trunk.

I have the same issue, but haven't wanted to spend the $$ yet.

[benzdude280]

I had the same problem and it turned out to be the bivalve. Heres the link: http://www.club202.com/forums/showth...ighlight=vents

Hope that helps you out.

[202rules]

So the vaccum pump is in the back near the passenger side? Is it outside the car? Because I think I started having this problem soon after I installed a new fuel pump, maybe while pulling on fuel hoses I loosened some vaccume lines!

I couldn't hear any weird noises from either the back of the car or in the engine compartment where the bivavle is. The bivalve seems in good shape from visual inspection.

[htfan1]

Originally posted by 202rules
So the vaccum pump is in the back near the passenger side? Is it outside the car? Because I think I started having this problem soon after I installed a new fuel pump, maybe while pulling on fuel hoses I loosened some vaccume lines!

I couldn't hear any weird noises from either the back of the car or in the engine compartment where the bivavle is. The bivalve seems in good shape from visual inspection.

The vacuum pump is located inside the trunk on the right side behind the side liner. It should be enclosed in a protective/sound dampening foam holder. However, not sure if the location changes with year/model.

It's possible some vacuum problems are not accompanied with pump noise. (However, mine SURE is!)

[Abuimad]

i got the car checked today (by 2 mechanics) for that ac problem i have been having...and both mechanics told me the problem was with some valve...and that in order to fix it, the dashboard has to be taken out...and a valve inside it must be replaced....does that sound logical and should i go with it ?

[jnolte]

it could be the dual valve

[martattack]

Originally posted by Abuimad
i got the car checked today (by 2 mechanics) for that ac problem i have been having...and both mechanics told me the problem was with some valve...and that in order to fix it, the dashboard has to be taken out...and a valve inside it must be replaced....does that sound logical and should i go with it ?

Sounds like one of the vacuum elements went out. I ended up pulling out my dashboard to fix it. Not really gonna do a write-up on it because it's just tooo damn complicated, but here's some pictures:

Click to enlarge:





The black and orange servo is what I had to replace in this picture:

[Abuimad]

ah damn that looks serious...do you have a pic of the valve that needs replacing ???

[martattack]

what type of A/C system do you have? Digital display..etc? or knobs?

[htfan1]

Originally posted by Abuimad
i got the car checked today (by 2 mechanics) for that ac problem i have been having...and both mechanics told me the problem was with some valve...and that in order to fix it, the dashboard has to be taken out...and a valve inside it must be replaced....does that sound logical and should i go with it ?

I'm afraid this is the exact same thing I was told by my local mechanic. Not only does it look complicated, it looks like a lot of $$$ to me.

[Abuimad]

digital

is there some kind of test i can run on the digital climate control i read it a long time ago....?

[Rocky]

The Bi Valve or the Mono Valve is located in the engine compartment.

It lies against the firewall on the passenger side.

This is for a M104 engine.

You do not need to take apart the dash.

[Sulaco]

Originally posted by Rocky
The Bi Valve or the Mono Valve is located in the engine compartment.

It lies against the firewall on the passenger side.

This is for a M104 engine.

You do not need to take apart the dash.

I believe you're thinking of another valve. I've had this problem going for about 3 years now. Only, my center vents would SOMETIMES work. Following instructions I found here on the forum, I replaced the valve under the hood, on the passenger side, underneath the plastic cover that protects all that expensive shit.

After replacing that, my center vents NEVER work.

I love Mercedes.

[fay31]

Hey guys your problem is the duovalve or bivalve like the other guy said, they are same thing.

[Sulaco]

The orange and black servo thing in the pic posted above?

[htfan1]

Originally posted by Sulaco
I believe you're thinking of another valve. I've had this problem going for about 3 years now. Only, my center vents would SOMETIMES work. Following instructions I found here on the forum, I replaced the valve under the hood, on the passenger side, underneath the plastic cover that protects all that expensive shit.

After replacing that, my center vents NEVER work.

I love Mercedes.

My car has the exact same problem and the REAL resolution was also confirmed by my local mechanic. He says the problem can only be fixed by replacing valves located in the dash.

[martattack]

I was in the same boat. My fresh/recirc vacuum element was leaking and ended up removing my dash to replace it.

It's not a good idea to leave it be for too long. The vacuum pump will be working extra hard, and will wear it out faster. That's not a cheap item to replace!

[Sulaco]

So which part is it, and where's it located in my m104 car? I'm capable of doing this on my own.

What's it look like? Same thing as underneath the hood? The orange/black thing in the pics above?

[martattack]

It depends on what is wrong. The Duo-valve is in the electronics compartment. It looks like two D-sized batteries on end. There are two coolant hoses on one side and one on the other. If that is the problem, a lot of times you can give it a nice tap with a hammer to try and free it up. That can help you diagnose.

If the problem is the vacuum element, depending on which one, you may have to take the dash apart. Some of them are accessible without removing the whole dash.

I'll post a little bit more on it later as far as which ones are easily accessible

[sultanC36]

thank you W202

you guys are the best i needed some help and could not finde it any were but here

you guys ROCK

[Vodka G]

had that problem a long time ago......a servo inside the vents went bad cost a fortune to replace it caz the dealer said they had to remove the entire dash....

it was covered under warranty :-) WHEW!!!!