Sometimes my heat and A/C will work, and when it does, it only comes through the dash vents for defrosting. So any vents actually facing the seats and the back of the of Jeep don't work at all. I heard that it could be a switch, but I'd like to hear more than just one idea.

 

It could be a vacuum leak, it could be an electrical problem. From your description of "works sometimes" it would be impossible to say for sure.

 

I have a vacuum leak, but that's with my brake booster. Would that affect it?