how do you power off the a/c?

Check here http://repairpal.com/automobile-owners-manuals-online or try this link you may be able to down load a free copy of the owner's manual for your vehicle http://www.autousermanual.com/

These cars have automatic climate control. You can select a warmer position and the A/C should turn off automatically. There is a MAX A/C setting which will override any selected temperature and set the A/C to the maximum output, however it won't turn off the A/C. Zee

There's a button that'll do it for you. Right hand column, about the middle.