Hello,

I am the proud owner of a 1980 300SD Mercedes. I've been working on the AC for a year now and it's been working from time to time. My main problem is that I've never found a diagram of the whole vaccum system (or at least the AC part).

The problem I'm facing now requiers me to identify a vaccum line. It's green/black and enters the "under the hood" section just left of the fuse box (I'm gonna post pictures tomorrow). I know it's related in some way to the AC because when I plug that green/black vaccum line, the Defrost air is cold (for a 30 secs).

Something odd I've found is that when I have that green/black line connected, the car doesnt stop when I shut it off.
But if you wait 2 mins after the car is started to plug it, the AC is gonna work and the car won't shut off.

I know I'm close to the solution, but I just can't figure it out by myself. I either need some diagrams of the vaccum system or need help from a non-neophyte.

Thank you

I love that early climate control system. It's probably a supply line for another circuit that has a leak somewhere, possibly A/C, hence the loss in vac to shut the engine down.

__________________
Adam Lumsden
(83) 300D
Vice-President of the MBCA International Stars Section

I'm certainly no mechanic, but I was having intermittent problems on my a/c, and one thing that fixed it, was a new idler pulley, damner, tension spring, and serpentine belt; in other words, all those parts having to do with that pulley. The shop said any TINY slip in the belt, even though it might SEEM tight, will cause the a/c to cut out.

Good luck!

1991 300d, 90k