Hey all,
I bought my E55 about a week ago, and as I was poking around under the hood, I found that a small hard vacuum line was broken right next to the duovalve (see picture). Does anyone know what this is for? I'd like to repair it, but want to know its purpose in case it has to be replaced.
Thanks.

 

Its pretty common for it to break. Forget what it is though. There's been recent threads on it. Just buy 12 inches of a smaller vacuum line that fits snugly over the broken end, cut the Mercedes connector out of the middle, and rejoin the two plastic ends with the span of vacuum hose. Easy.

 

Hows your climate control working?

 

Thanks for the responses. Shifter, the climate control is wonky to say the least. Comes on normally, but soon the center vents nearly shut down. After that center is warmest, followed by side vents (a little cooler), then top of the dash. I used a thermometer on the vents and got center: 74 degrees, side vents 68, top vents 54! After reading posts, I was thinking maybe the duovalve was sticking. If that vacuum line impacts the climate control it would sure be an easier fix.

 

I don't think its the duo valve. It's something by the throttle body.

 

+1

I actually have a pic in one of my posts re:this same issue

Easy

Btw welcome! Post pics or be banned

Armani

 

That line is your vacuum supply to the vacuum elements in your dash, controlling your vent positions. without it, it will go into default, which is defrost. So, fix that line and your a/c may just work normally.

 

Shifter, my hat is off to you. After your clue, I discovered that sometimes it IS the little things. My climate control is back to normal.

 

glad it's fixed.

 

Hello, Shifter. Plz share any ideas/thoughts you might have. Thx in advance.

I have the vent control issue with my 99 E320 (w210). Heater/AC work fine, but the problem with controlling the vent direction. I've found the posting by beachcomberbill, and read your comments - the grey vacuum line under the hood controls vent positions.

I checked the grey vacuum line by DUO valve in my car, but it seems fine. (no crack/connected fine) I've noticed the vent control sometimes works (very rarely) but most of time it doesn't.


Would you guide me where to start? Please!!!

 

You might want to try PM'ing him and throwing in a link to this thread. It's over 6 months old and he doesn't own a W210 E55. I doubt he checks in here often.

 

I have the same issue with my 2002 E55. Can someone give me the detail on how to connect the vacuum tube back?

John

 

I think the line breaks because it's installed without enough slack between the 2 ends that are connected together.

Easiest way is to cut off each connector and splice a piece of flexible hose in-between the pipes.

If you're a purist I suppose you could order the hard line and connector and "re-tube" it.

Off of AutohausAZ, the flexible tubing is "Vacuum Hose/Line; Black Rubber 3.5x7.5mm; Bulk", PN 1179970982 , and the hard line is "Vacuum Hose/Line; White; 4mm OD; Bulk", PN 0001581435. Both are sold by the meter.

Timeliest fix would be to cut one of the ends off and take it to your local autoparts store and test fit it to make sure it's snug. I happened to have some extra BMW hose for a vacuum advance laying around that was a perfect fit.

 

I know I am reviving an old thread here, but I have been trying to track down a phantom A/C vent issue for a while now. Basically since I bought the car I would notice that after about 5-10 minutes of driving, the A/C would stop blowing out the center vents (assuming I had the climate control set to AUTO or manually selected the upper vents) and default to the defrost. After finally doing some reading about this I realized that I had a vacuum issue, since the vent system will divert to the defrost setting when it loses pressure. Sure enough, I tracked down a disconnected vacuum line (light gray color) behind the firewall - one end protrudes from the firewall and connects to a small rubber hose near the intake manifold, and one crosses near the duovalve on the passenger side of the engine compartment as pictured in the OP's post.

My vacuum line was completely missing the little grey adapter pictured as broken in the OP's post. I reconnected the vac line to the intake manifold tube, and slipped some old windshield washer rubber tubing inline where the broken plastic connector used to go near the duovalves.

That seems to have partially fixed my AC issue - the vents no longer default to the defrost, however, after 5-10 minutes of driving the air from the center vents decrease considerably, however the side vents remain strong and air does not default to the defrost. While this is an improvement over my original symptoms (where the center vents would completely quit blowing air, most of the air would be pushed through the defrost, and a small puff of air would continue out the side vents), I believe my temporary fix may not be completely creating a 100% seal.

Does anyone know how critical that little Mercedes adapter/connector is, or should I just focus on finding an aftermarket vacuum connector (for cheaper) to create a better seal? The only reason I hesitate is that the Mercedes part appears to have a small reservoir built into it, which I question whether that is part of the design?

Any help is much appreciated.

 

You may want to obtain a vacuum pump and verify that the gray hose you reconnected can hold vacuum.

 

FYI for anyone down the road looking for an answer, the plastic connector is actually two parts as better illustrated in the pictures in this thread:

http://www.benzworld.org/forums/amg-...mber-help.html

That seems like way overkill. The part numbers are as follows:

1) 90 degree connector #: "202 800 02 53"

2) Straight connector #: "202 805 03 44"

There is no way I am going to buy the replacement Mercedes parts for this and will find a standard vacuum line connector to replace my temporary rubber hose fix.

 

Just a quick update on this thread - I guess that rubber tubing they use for wiper fluid shrinks, as I noticed on the drive home the AC was acting completely functional with no decrease in power from the center vents. Sure enough I checked my rubber tube and it was very tightly sealed around the old vacuum tube on both ends, creating a very good seal/suction. Problem appears to be solved - woohoo!

 

Guys thanks for the info. Dealing with the same broken line and the four wires to the duovalve plus a few at the nearby ground. I guess they were in the way of the nest some squirrels were trying to build last winter.