how can i fix my heater on my mondeo st200?

my function settings on my heater control unit wont let me change from the windscreen it all works fine bye this it blows hot and cold air the air con is ice cold the climate control all works fine it just wont let me change to my face or feet ive changed the switch the black resistor checked the vacum presure also traced all the vents all are fine can anyone help

drew
February 2010