Narrow it down- does the vibration occur only when you are driving (moving), or anytime the engine is running (neutral, park)? Does the vibration increase with engine rpm, or does it increase with forward speed? Or is it a constant regardless of forward speed or engine rpm?
Nothing wrong with a fixed/mechanical fan- like you say, they can be a bit noisy at times, but with the space limitations in an early A, ya gotta do what you gotta do. I'd be a bit leery with a flex fan though, especially the cheaper ones. Lots of horror stories out there.
