Kent,
I have a 1982 300SD with a new radiator, hoses, thermostat, fluid with correct ratio, fan clutch, blets all from Mercedes Source. I recently to a trip to Las Vegas where it was 114 most of the time. When driving on the highway at 65 mph I had very normal engine temp and my A/C was ice cold. As soon as I got into stop and go traffic, all bets where off. The engine temp climbed to just under the red and my A/C was warm. The aux. fan was on and the fan clutch seemed to be working just fine. The condenser fins don't look to be blocked either.