The ACC on my 300TD has been non-functional since I got the car a month ago. It just blows air kind of out all of the vents. Took the ACC out and reflowed all solder joints, although everything looked good. No change.

Today, I began looking at the vacuum system in earnest, replacing any questionable tees or hoses and generally looking carefully. Lo and behold, I noticed that one hose that goes through the firewall was disconnected under the dash. Dang if I can find where it goes. My vacuum gauge shows that the vacuum on that hose modulates when I switch the ACC.

This line gets its source from two electric-vacuum frohickeys mounted on the left inner fender. These are teed into this line which has a filter on it and then it goes through the firewall. See attached pic; it's the one with the filter inline.

I have spent about an hour under the dash and I cannot find where it goes?

Help?

Thanks!!

-Dan

Attached Thumbnails

 

__________________
1976 w115 300D 4-speed conversion!!
1985 w123 300TD 4-speed conversion!!

Non-Mercedes old stuff:
1941 Buick Special (Straight 8!)
1946 Luscombe 8a
1947 Willys CJ2a
1950 Chevrolet 4400 dump truck
1954 Chevrolet 3600 3/4 ton
1954 Cessna 195B
1955 John Deere model 40
1991 Ford Taurus SHO
2013 Jetta SportWagen TDI 6-speed (I sold out...

It's just a vent hose. Doesn't connect to anything.
r

__________________
1985 300SD
1998 Jetta TDI
Previous: lots of diesel VW's, MB's, KW's, Pete, Freightliner


Walking isn't a lost art: one must, by some means, get to the garage.

hah! I guess that would be why it has a filter on it. Thanks!!

-Dan

__________________
1976 w115 300D 4-speed conversion!!
1985 w123 300TD 4-speed conversion!!

Non-Mercedes old stuff:
1941 Buick Special (Straight 8!)
1946 Luscombe 8a
1947 Willys CJ2a
1950 Chevrolet 4400 dump truck
1954 Chevrolet 3600 3/4 ton
1954 Cessna 195B
1955 John Deere model 40
1991 Ford Taurus SHO
2013 Jetta SportWagen TDI 6-speed (I sold out...

Finding a complete and accurate vacuum diagram is difficult. There's a link, but you'll probably have to figure out some variations, particularly if a PO modified the system:

Mercedes Vacuum diagrams

Cool, yes found this gem in that post ... and as far as I can see this car is bone stock.

So, still scratching my head as to what's wrong with the climate control. I was hoping for an external reason for the problem, but I'm guessing that the problem lies in the actuator mechanism itself... and can't imagine that's going to be overly pleasant to get to ...

Any thoughts here?

Thanks *very* much!!

-Dan

__________________
1976 w115 300D 4-speed conversion!!
1985 w123 300TD 4-speed conversion!!

Non-Mercedes old stuff:
1941 Buick Special (Straight 8!)
1946 Luscombe 8a
1947 Willys CJ2a
1950 Chevrolet 4400 dump truck
1954 Chevrolet 3600 3/4 ton
1954 Cessna 195B
1955 John Deere model 40
1991 Ford Taurus SHO
2013 Jetta SportWagen TDI 6-speed (I sold out...

The diagram in that link is all well and good, but it's very engine oriented and not much help for ACC. It does show your vent line and filter nicely, though (85-to-a)

Now you need to see about the things identified as "c" other consumers.

Scans of airflow for W123 climate control

Airflow management from the ACC is a mix of electrics and vacuum. The dark black line in the lower left scan links the climate control (VACUUM SOURCE) to the vacuum system (the 4-way T saying "other consumers").

If one or more of those pods has a significant leak, it'll affect airflow management. Test via push button, then isolate and overcome.

The other "other consumer" is the central lock system. Leaks there may also affect the airflow, depending on the location of the leak and the integrity of the check valves.