The other option is to buy the fan....make sure it is fully returnable...then lay it on top of your radiator shroud, plug it in, and turn the AC on...

If the fan does not spin, you have some other problem.

I thought of this, but I think I had trouble finding a fully returnable fan..even on Amazon.

Based on online reports, I happen to think the aux fan crap out on an E53's more frequently than on E39 or E46..which seem to last the life of the car....maybe yet another example of inferior parts supplied to US-made cars like E53. I can't complain too much though, 15yrs for a fan is not bad.