I thought om617 didn't have a fan clutch, at least my om616 didn't.
Try to remove the water radiator and clean it thoroughly. Then clean the a/c radiator as well without removing it so you don't loose a/c gas. Clean them from outside as overtime a lot of junk gets between the radiators.
A buddy of mine has a w124 200ce (gasser coupe) and whenever he was using the a/c the car was overheating. Cleaned the radiator and the car works flawlessly now. There was a lot of junk between the radiators.