Even as someone living in Canada (where it can get to high 30's and high 40's with humidity) I can tell you the AC is absolute garbage in these trucks. It works, don't get me wrong, but you will never have to lower the AC on a hot day. In fact, you will have it maxed out and still not feel completely cool in the vehicle.
Something is wrong with the design and I reckon it has to do with the baffles/flaps inside. I have had moments where the AC all of a sudden is amazingly cool and the sound the system is making is different only to have that go away after 5-10 seconds and go back to it's crappy performance. But don't let that stop you. I would still consider buying another RAM even with this AC.