'08 Expedition HVAC LOW AIR FLOW vs RECIRCLE???
 

Newbie here. With fan on full speed have good air flow thru all vents (defrost, dash, floor) when "recircle" is engaged to draw air from inside. But, when turn recircle off, the air flow volume drops way off although fan speed stays up.... Doesnt change regardless of selected duct (defrost, dash or floor).
Have replaced the air flow comtrollers: 7L1Z-19E616A (YH1874) - this is "A" position above blower fan on drivers side. Also replaced temp blend door controller 7L1Z-19E616C(YH1873) - this is "C" position on top of the main air duct housing, is located directly behind the radio/CD/GPS display. But problem remains same......
Thoughts?

This is not an electrical or electronic or a control problem, the vehicle simply cannot "breath" when outside air is selected.

1. Open a rear window and see if the volume of airflow increases markedly. If so, inspect the outlet air vents.

2. Check the inlet air path for a blockage or restriction. Check cabin air filter (if equipped).

Thanks for additional troubleshooting thoughts.
Checked Ford manual and their parts catalog along with vehicle and there is no cab inlet air filter on the fresh air intake.
Also checked difference in air flow with windows and door open vs everything closed up and makes no difference in air volume output....
So little bit at a loss as to why the drastic difference in air flow volume between recircle and fresh at same fan speeds.
Ford dealer estimates over $350 to troubleshoot and resolve, they only noted the two possible controllers I replaced for $50, an hour + of my labor, but that didn't solve problem.....
Not certain where to go next, outside of paying them to diagnosis and fix.
Any further thoughts?
Thks!

Go and inspect the inlet. Something is restricting airflow....

Now, that said, it is very much normal for the airflow to be less when forcing air through the cabin rather than recirculating it. Make certain you are not trying to solve a "problem" that is actually normal behavior.

In the Fords that I've owned, the recirculate setting has always had a stronger air flow than normal. I tend to agree with projectSHO89.