Finally fixed this problem.

I believe that pslsnakes was right on target. There was a single, thin wire that had a blue cover over its connector that led to the alternator. I'm assuming that this was a ground wire that had been inadvertantly disconnected when the fans were removed. It is located on the left side of the vehicle near the bottom corner of the radiator. Since I did not have the car elevated it was difficult to see the wire. Once connected the fans worked as designed.