a/c -heating vents
 

The vents in the car seem mostly to come out of the defrost area ,it used to be a fantastic system nice cool or hot burst of air comeing from the center now very little air comes out the center if anyone knows what the heck is wrong with it and what i can do it, It would be of great help thanx...

Depending on WHAT MODEL YOU HAVE, I would check for vacuum leaks.

I'm not REAL clear what symptoms you're having, but the center vents should NEVER issue hot air. On some models, warm air comes out of the SIDE vents, intended to clear the side windows.

More info, please -- what year/model, like Benzmac says, and specific behavior of your system -- would be most helpful.