Although I did prepare for intense AC on my latest trip with a long sweater with hood and an Amtrak blanket, I still got cold overnight on the Southwest Chief (coach, but they say it doesn't matter) in July in the southwest. I'm just curious at this point (because I know one needs to be like a boy scout-and there are a lot of them on the SWC-and be prepared for all eventualities), but is there a master control for the AC for the entire train or are there areas that are controlled separately?