1994 Chevy Beretta no front defrost

Heater problem
1994 Chevy Beretta 6 cyl Front Wheel Drive Automatic 184k miles

when I put the selecter switch to either heat or defrost hot air blows out of the front vents no heat is felt at the windshield and no heat is felt at the floor vents when the selector is put to the "heat" position.I was able to find out that the selector control is a switch, not the old style of a cable opening and closing a vent door on the heater box to divert/direct the hot air flow.