2002 Jeep Cherokee heat problem

Look up under the dash on the passenger side and you should see where the heat should be coming from. The only thing I can think of would be a door not opening. These are usually ran by vacuum. Try and see if the lvac lines are hooked up. Sorry been awhile since I worked on the vents of a cherokee. Let me know what you find and ill do some reading. Hope I can help Curt