automatic transmission maintenance and minor radiator fan noise issue

I have a concern and a question. First the concern, in the manual it is not clear to me when the automatic transmission fluid should be changed out. I think they basically say if there are no leaks then there shouldn't be any worries, I believe it's one of those sealed for life transmissions. The next thing is that at certain times especially with the a/c on the radiator fan comes on, and it appears to spin at a very high rate of speed which causes vibrations and noise. The cars been a pretty good one other than the maintenance and minor vibration/noise thing.
Thanks in advance for the help.