When I turn on my heat it will only go through either the defrost on the windshield or the floor or both. It will not switch to the front of the dash. Whats wrong with it? I have a 1998 Jeep Cherokee Sport with 4.0l I6
I need help!! lol

 

There are hundreds of thread on this. Try giving the search function a try.

 

Check the vacuum connections behind the temp control panel. Look for loose or cracked hoses or damaged part.