A/C blows fine, but no air coming out when on heat
 

I have a 1996 pre face lift cherokee and the air blows fine out of the vents on every setting except heat, i can hear the blower motor going, but all of the sudden no air. Ive checked everything i can think to check and im coming up empty handed. Anyone else experience a similar issue. Maybe a blend door problem or some sort of vacuum leak?

Yep. Check for vaccum leaks. Sounds like a blend door problem. First place to look, anyway.