Back again with another post.
2003 discovery 136K miles.
When we turn the AC on it blows mostly through the defrost vent, and the position is set for front vents. A small amount will come out of the front vents, but it seems that something is off (or possibly blocking) the vent air flow director.
Thanks for reading and appreciate any help on this one.

 

Ive gone through this exact issue.
Had to replace the flap actuator.
when you select head/feet/floor etc, do you hear anything?
The motors are located just behind the glove compartment.
If you remove the door, you'll see the fan motor and to the upper left
will be the actuators.
The top one selects defrost to head, and the lower one selects head to feet I believe.
Also, all of the foam pieces between the different ducts were rotted, allowing the
air to go wherever, regardless of selection.
I taped them all off with A/C metalized duct tape, no problems since.
I'll warn you, its a tight fit up in that dash.. patence and curved tools
will be a must.
Hope this helps!!

 

Thanks for the quick reply GST_ Greg!
I used to work on the 68-82 corvettes, they were really a PITA too.
I'll be sure to let you know the outcome.
Many Thanks again!