More pics "failure mode to the sword, no fan - DIY repair" http://www.bimmerboard.com/forums/posts/1249909
John sent me an email with the pics: Hi Erich, I wanted to update you on the inoperative blower situation. I’ve found yet another failure mode on the sword, cracked solder joint on the connection between pin #5 and the circuit board. I’ve added pictures.
Wave soldering is great for some things, like surface mounted components, but given all the places that we've identified poor or broken connections in the various components of our cars I have become very sceptical of its use. Pioneer had similar issues with the power supplies of their Elite HD projection TVs from about this same time period, and the fix was to re-solder by hand every connection on the circuit board... Pioneer's solution was to only re-solder the connections broken at time of the repairs. This practice ensured that the board would fail again. The common thread I see is high current draw, possibly too light conductor, and resultant higher than needed temperatures on the connections. The heating up & cooling down cycle is just like water freezing in the crack of a rock, eventually the solder fatigues, crystallizes, cracks & breaks. Unfortunately, given the age of our cars, and the number of cycles they've endured, I suspect we will be seeing more of these issues in the future.Re-soldering adds material which strengthens the joint as well as providing additional mass, larger contact area, and taking longer to heat up & cool down, helping to reduce the stress on the joint. Thanks again, John