fred- i'd advice you to do a regular tune-up stuff first. if your problem (high rpm) persists, check your overvoltage relay.
it fixed my similar problem.

as far as your a/c concern, it would be best to see an a/c
specialist, who could figure it out. if your a/c is cooling and
your motor fan is working, it doesn't look like a big dollar ticket
item. cheers!