The immediate problem with the van fan was loose wires, which sort of explains why the problem was intermittent. Fixing that including the original fee for diagnosis would be about $225. However, while looking over the van, they found that the oil cooler lines were leaking (which might well explain why I continue to have occasional fluid drips). I told them to go ahead and fix it, since the point of this is to keep the vehicle running and in good condition. Estimated total damage: $650.
The good news is that they say they'll have the van ready for me sometime tomorrow afternoon, so I won't have to rent a car on Monday to go to work.