"You should NOT see any bubbles or signs of aerated freon in the sight glass..."
Not necessarily so. On some MB A/C systems it is perfectly normal to see a small amount of bubbles in the freon. In fact on my 108, with a fully charged system, the bubbles cycle with the compressor - you see clear for a few seconds, then some bubbles for a few seconds. I asked about that here on the board and learned it was normal.
If all you see is white bubbles all the time, then you are probably low on charge.
Hopefully, in the coming week I will be able to compare A/C systems between the 108 and the 126, just waiting for some R-12 to arrive.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.