Strange A/C problem

Seems that the AC only works on the passenger side of the system on an '03 TB. The passenger side vents blow cold air, but the driver's side will NOT blow anything but warm air. I thought it may be a blend door problem, but it behaves normally when I turn the driver's side thermostat to heat and back, it just won't cool.

Does the dual zone thing use only one evaporator, or is there a separate one for each side?

Any ideas?

The ducting is split, same evap. the is the issue most likely the temp door is binding in the max cool position, you've got to get into the system and see what's up, no quick fix here.