The Aveo has very limited options - and AC is not one of them. Basically, Aveos come in 3 trim lines, and the most basic "LS" has roll-up windows, manual locks & mirrors etc + no AC. AC can be installed after-market, but I think you are better off looking at a higher trim level that includes AC
The LT1 model includes AC, keyless entry, power windows, locks, cruise and satellite for about $2000 more than the stripped LS.
The LT2 adds bigger wheels (15"), foglamps, and upgraded upholstery and maybe a few other minor details for about 1200 more than the LT1.
IMO, the basic LS - lacking AC would be fine in northern climes where you don't need AC. If you want an Aveo with AC, I think you are better off getting the LT1 model Aveo than having AC installed after-market to the base vehicle.