ac\heater control on 2003 Ford Crown Victoria

air doesn't always come from vent even when vent is selected. ac flows from floor and defroster most of time and occasionaly goes to vent.changed vacum selector valve and no change

2 answers
I have this same problem. The climate control system went out. It wont control the vacume system to open and close the vents. You either have to replace ($600 delership or $200 yourself and very easy todo) or pull out the vacume hose contector to it and buy $1 hose to conect the blue hose to the yellow one. this turns on the front vents.
There must be a blender door somewhere that is not opening or closing it could also be the control system itself i suggest you let someone check this out a qualified shop.