I have a 2005 f150 and air is only coming out of defrost I had this problem before and it was the control head and replaced it but this time it is making a noise like a vacuum pump is running for a few seconds then stops. Does this everytime I crank the truck and then every few minutes. I am thinking the pump is bad or I have a hose leaking. Anyone had this problem or know where I should look first for common vacuum leak places? thanks in advance

 

2005 F150 uses electric actuators to control the HVAC system. There are 3 actuators.

1) mode door - controls which vents the air goes out of
2) blend door - control temperature
3) recirc door - outside/inside air

Looks like your mode door actuator is faulty. Do a search on mode door. luckily it's just the actuator and is a easy fix. You will be unlucky (like I was) is you take off your actuator and feel that the levers it moves are jammed. Then you have to pull the whole dash out to get the jammed felt out of the mode door itself.

 

I have simular problem on 1998 Expedition 4.6 XLT without heat and all the airflow regarless of vent and blower selection comes out the defrost can you assist. Not sure how many doors or actuators but I have front and rear HVAC. I found the front actuator motor and it seems to be turning as it should. No heat in rear either but normal air flow between floor and panel selection.

 

The dash's airflow selection is controlled by vacuum. Check the vacuum line adjacent to the battery for damage. Very common on 03 and older.