I am only getting air flow out of the defrost vents the switch can be set on A/C, heat, panel, defrost it does't matter

 

Welcome to the site!

This link may be of help to you. https://www.ford-trucks.com/forums/7...xpedition.html

 

there are 3-4 different vacuum cyliner operatate doors in the air duct. when you loose vacuum the default is the air goes to the defroster area. YOur loosing vacuum. Check the hoses at the firewall between the motor and glove box area. Check the vacuum modulator behind the passenger side fender well. Make sure the swith on the dash is acutally turnging the **** shaft and not slipping on it.