ok this is a odd one,most people do not have hot air and the cold works just fine.
first check to see if oyu have any codes. since you have a limited with dual control its simple.
go to http://wjjeeps.com/climate.htm
and follow the steps underAZC self-diagnostic mode
most likely you will get one that says door travled to large or small.
and if so you can do a simple $200 fix in under an hour by yourself at home.
i did a write up on it take a look http://www.*********.com/forum/f13/d...p-pics-884932/
this is the part that lets you keep dual control and you dont have to take apart the dash http://blendorstore.com/l
i ordered it his ebay store since was a few bucks less
hope it helps and let us know what codes you get