There are ATM's at the airport... i seem to remember a orange unit, so either HSBC or Scotia bank... there are more as well, either banamex or bancomer i think. They are located on one side of the doors as you finally enter the airport waiting area after customs and the time share guys...
You do not have to go to centro for a ATM.. there are banks and ATM's scattered around the city.. Do a search on google for them..