[Ds86C10]

i have no control over my heater box. i slide the selector to any position and it blows out air where ever and when I come to a stop the air mix door moves so I lose heat! what is going on here??? its like i have no vacuum... So where is the source of vacuum for the controls come from??? i need help asap since its freezing cold and i cant drive down the road like Ace Ventura again when my windsheild needs defrosting.... Thanks