Passenger side is blowing cold air and driver is not why?

That vehicle has five different door motors. There are two that control the temperature of the air out of the vents. Left andrRight.

To get to the left one.
Remove the instrument lower cover left hand.
Remove fuse block cover, remove screws and remove lower panel.
Remove the center console side finisher left hand.
Remove the heater and cooling unit foot duct left hand (2).
Remove the tire pressure monitoring system receiver.
Disconnect the air mix door motor connector (1).
Remove the air mix door motor screws (A) and then remove the air mix door motor left hand.

Here is another image. The temperature blend door will be on the left side of climate box. See #3 on image.

That is the blend door motor for hot or cold air. Those motors usually fail. Remove the motor and make sure you can move the blend door manually while the vehicle is off. If you can not move the door back and forth with ease then you will need to replace the climate box. If the door is okay then replace the blend door motor.

There are two separate paths for the air to go through. One goes to the passenger side the other to the drivers side. There is a different blend door and motor for each side.