1998 E320 4-matic: 2 questions

[knuckle_buster]

Hi everyone...I decided to do some badly needed maint on my '98 E320 4-matic (210-082). First, I changed the spark plugs. That was a real pleasure. That engine compartment has more sharp edges than a Beni-hana.When I finished the spark plug job, I noticed a vacuum line loose. I can't for the life of me figure out where it goes. I even checked WIS, but can't seem to find that level of detail.If you remove the plastic cover on top of the engine, there are two lifting eyes at the back of the intake manifold (tranny end). The small vacuum line comes from a nipple just below and to the right of the leftmost lifting eye (driver's side in US). The line is maybe 6-8 inches long. Where the devil does this go????Also, I decided to add some freon to the A/C, because it wasn't cooling well. Does anyone know what the freon pressure should be (in Bar), with the engine running and ambient at about 75F, as read from the climate control computer? It indicated 4 bar with engine off, and 6 bar when running. I added about half a can of 134, and the pressure went to 9 bar. Then I got scared. The last thing I want to do is over-pressurize the system and do the dreaded evaporator replacement.Thanks in advance!

[Hirnbeiss]

Is it the one that attaches to the white plastic hose coming out of the firewall insulation in the middle, where the heater hose also goes through?

[knuckle_buster]

It is right in that area. I don't recall seeing a white hose or a nipple for it, but I'll look this morning. Thanks.

[knuckle_buster]

That was it. Apparently when it came loose, the white plastic tube retracted into the cavity at the firewall, so I couldn't see it. I had a devil of a time getting it back out. Thanks again!

[Hirnbeiss]

I am not an expert on AC, but I have heard a thumb rule that high-side pressure should be in the range of 2 to 2.5 x outside temp in Fahrenheit. 2 x 75 = 150 psig, which would be about 10 bar.