Hmmm. Well this looks like the same issue I feel like I'm having. 08 Spec-b.
I posted this elsewhere...
The driver's side when set to mid 70's is pretty warm, and if my passengers side is set to the same temp or hotter, it's actually blowing cooler air than the driver's side even if I put the passenger up to 85. Also blowing at the feet, it is not that warm either to match the temperature and seems to be blowing colder than my driver's side.
Also, when I turn the vent on to blow at my feet, it still blows out of the middle vents between my nav system. The only way to get it to stop from those vents is to switch to the front defog and the feet blower.
Do you have the part number by chance?