[QUOTE=Richard Wooldridge;2283726]Your 1979 450SL has the very troublesome climate control II system. To verify this, take note of the fact that you have buttons vertically oriented, and a separate AC rocker switch to the right side of the vertical row of buttons. QUOTE]

Yes, precisely.

Apparently all roads lead to waiting for my radiator to come back from the shop, re-installing and starting the car to check the A/C operation.

Regarding the vacuum system, it seems to be working fine. Automatic Door/Gas/Trunk locks all operate, and vent controls seem to be fine too. Perhaps a bit sluggish, but I don't know how fast top-notch operation is / was in the first place.

Regarding the servo, I will open it up and inspect, but it looks fine from the outside...however when I got the car I remember the mechanics at my shop pointing at it and saying to each other something like, "Oh yeah...it's got one of THOOOOOSE".... I guess they are truly known for their bad reputation.

Appreciate all the comments...

Stu