99 LHS Heater blows cold air

I have a 1999 Chrysler LHS the heater only blows cold air and only on the floor. It doesn't matter where the control is set. Is it the control unit or a blend door problem?:banghead:

The LHS has vacuum controled heating and cooling system. Trace the vacuum hoses coming from the heat controller and the vacuum hose coming from the vacuum solenoid in the heater hose close to the fire wall. You may discover a hose broke or slipped off a connector. Good luck