Air conditioning

When on Auto AC the cold air only flows on the passenger side, air flows on driver side but not cold. Would like to know how to fix? Thank you
Great, very much looking forward to a response to my problem ( my car xsi 2ltr manual, hatch) delivers AC cool air to passenger but not the driver vents, all else seems correct with the AC the heater works and delivers as supposed to vents as directed.
Perhaps the fourteen degrees which is the lowest on auth AC is a little ambitious to achieve in Melbourne conditions at the moment where we can be in the mid thirties every second day.
The request is to know how to go about identifying as to why the driver is not receiving cool air while the passenger is.
Thank you.

Rob