JEEP DEFROSTER NOT WORKING

My Heater Only Works On Vent. If I Put On Heat Or Defrost The Fan Does Not Work, But I Put It On Vent Or Any Other Setting The Fan Works...

We Have A '97 Wrangler And The Defroster Does Not Work. The Heater Kicks @#$ On The Floor And Dash. But When We Switch It To Defroster It...

My Heater/ac Fan Only Works On The Highest Setting (4/4) And Now The Defrost Does Not Work At All. I Can Have The Heater Blowing Out Set On...