Originally Posted by cAAl
Yes. I've done it a bunch of times. Just take the train below the baggage claim from Terminal C to Terminal A. Unfortunately, you'll have to clear security once again when you reach Terminal A.
There is a train behind security that will take you between these two terminals. Check out
this map for more info. Of course, this depends on which part of terminal A you'll be in and I have no idea where exactly AA is there.