96 civic dx. Heat works but only stays on face vents but will switch to floor but not defrost for the window where I need it the most. What could be the problem? Thanks ht.

 

sometimes heat doesn't always defrost the best. use your a/c to defrost the front window, its much faster.

 

could be a broke flapper in the vents! take your ac/heater control cover off and look and see if the lever moves listen for a flap noise when you move it to defrost position if it dont work you gotta take the dash apart and see what is broken?

 

Thanks guys will do.