A little more info about your Jeep would be nice. I.E. year, model, ETC. If you have the dual zone climate control system, it sounds like the blend door problem. Do a search of the forums using key words "blend door" and you should come up with a few threads about your problem.
Previous Jeeps: 84 CJ7 (A True Jeep), 2000 XJ (163,000 Miles/Totaled (Pictures of wrecked Jeep in gallery)), 2004 WJ (parting out die to major electrical issues)
If you don't have time to do it right the first time, how do you have time to do it over.
Lifetime member #13
2011 Tango/Mango JKU