Auto Parts: 1998 Chevy S-10 Blazer, time heidi, heat vent

Question
In my 1998 Chevy S-10 Blazer the floor heat vent is no longer blowing any air.  When I set the control to floor, the heat blows from the windsheild defrost vents only.  All other vent controls seem to work fine.  

I already checked the vacuum line that goes to the heater door that's next to the gas pedal and it's okay.

Do you think it could be a bad heater control head?  What exactly is the heater control head?

I would appreciate any suggestions.  

Thanks for your time,
Heidi  

Answer
sounds like the blend door actuator is bad or the door itself is jammed with crud. start by looking in the heater vent with a light to see if there is stuff blocking the door also look to see if it tries to move when you select the heat to the floor. the heater head is whats in the dash. it is just a big switch that diverts the vacuum to the correct place.