Was the car at high idle...
and did you have a fan blowing across the condenser ?
Were you installing vapor and into the low side valve ?
Are you sure your compressor engaged ?
Did you jump the pressure switch to get it to engage or did it due to pressure getting high enough ?
Did you have the inside temp control set to max and the high blower on ?

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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