Hello. The discharge location is controlled by the mode door actuator. The blend doors are for hot and cold. Here's info on both:
The dual zone system has two blend door actuators, one for the driver side blend-air door and one for the passenger side blend-air door. There is a single mode door actuator and a recirculation door actuator.
BLEND DOORS:
MODE DOOR:
The mode door actuator is contained within a black molded plastic housing with an integral wire connector receptacle (2). An output shaft with splines (3) connect the actuator to the mode door linkage and three integral mounting tabs (4) allow the actuator to be secured to the air distribution housing. The mode door actuator does not require mechanical indexing to the mode door linkage, as it is electronically calibrated by the A/C-heater control.
The A/C-heater control must be recalibrated each time an actuator motor is replaced.
The mode door actuator is interchangeable with the actuators for the blend and recirculation-air doors.
All this said, you may just have a calibration issue. The FSM says the actuators are calibrated with a scan tool. With Gen IV vans you can calibrate from the HVAC control. Not sure if that's the case with your Gen V...but someone will chime in I'm sure.
Calibration procedure is also dependent on you type of HVAC control unit, e.g., single/dual zone, front-only versus front and rear, digital versus manual, etc.