OK.... I checked various vacuum tubes once I was able to follow some of the color switches (I do have a W116 manual on CD) that were apparently added on at a later date. I was never able to find the vacuum resevoir which I think is supposed to be behind the driver side wheel well. I know there is another one in the trunk but I'm not sure it has anything to do with this issue.

I unplugged the control switch behind the dash a checked vacuuum there at the tubes. They all seemed to hold a vacuum and I could hear some switches click.

The upshot was I connected the black vacuum tube to the tube that controlled the side flaps (hillbilly rigged it)and got both a/c and heat (bi-level and auto high and low, though the fan may run at only one setting and never cut off) depending on the temperature dial setting. On this setting it appears that the A/C compressor runs all the time, which I think is probably correct.

Mt question is: Do I have a faulty vacuum switch on the dash?? That's is my best quess. Any other suggestions? Is such a dash swith available anywhere, new or used?

Thanks in advence for any assistance.