First, I believe the diesel has a visco clutch (at least the 2.5L I saw Saturday does). No doubt yours is covered with sticky black oil and is non-functional.

Second, check the fuse for the aux fan, they fatigue and break. Also check the fan by wiring direct to the battery, they do sometimes fail (although not often).

Electric fan is switched on by a temp sensor on the engine, I believe, just like the older 61x engines. Aux fan should also run in slow speed when the AC is on via a pressure switch on the receiver/dryer.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!