Max cool, blower low.
Do not trust auto-lo.
Since you are having problems.... you might need to borrow a good fan...
the air over the condensor is the bottleneck of all AC systems.....
If that is not sufficient it can screw up your diagnosing...
In fact i believe that is one of the situations where when using the sight glass to fill the refrigerant it can cause a false ' add ' signal... causing all sorts of other problems..

How about the fins INSIDE the evaporator being cleaned before you start any of this other stuff ?

This would be about the minimum...
http://www.northerntool.com/shop/tools/product_200007224_200007224

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html