O.K., so I have poor airflow at the panel. I mean, it gets hot here in south MS and I have to run the blower on HI to get barely enough air blowing. Took it in and had it checked, dealer said the blend door was broken. Changed under warranty but no different. Took it back a couple months later, the Service Mgr. told me that Chrysler has a Service Bulletin out on the Mega Cabs. Apparently there's a diverter or baffle or something behind the dash or under the console that sends more air to the rear vents. There's no fix for it so you just have to sweat. I deal with it by closing off a vent or 2 on the panel to push more air on me. That don't work too well when the wife's in the passenger seat though.
Anybody else got this issue?

 

not much you can do. The mega cab came with the same a/c system as the quad cabs. The system isn't adequate enough to keep the bigger cab cool, especially in the warmer climates. If you don't care about the back vents working, you can pull out the center console and underneath is the ducts for the rear vents. You can take it apart at a joint that's under there and block it off.