I think I got it!!
I was fooled onto thinking that the fan was fine because it would run strong on the bench and then quit running soon after starting operation in the car. After re-soldering the temperature control with no improvement, I decided to replace the brushes in the fan motor. VIOLA!!
See: http://207.210.95.34/~boostd/
The proof test will be tomorrow after a long day in the hot parking lot.
Thank you all, especially Dave, for your patient indulgence.