I tried adding a fan to my Longboat Prusa. It was an old CPU fan I had, and I mounted it (with tape) on the carriage pointing at the extruder tip. It was permanently powered on.
This produced a great improvement in the printing of overhangs and pointy bits, but the resulting objects were unusably fragile. Presumably it was setting the PLA before it was thoroughly stuck to the previous layer. Is this just the result of too much airflow?
I can easily get a less powerful fan. But can I control it from Sanguinololu electronics that are already controlling the hot-end heater and bed heater? I have seen suggestions that some firmware might be able to control a fan connected to the unused PWM pin, is that right? I am currently using Sprinter.
