The driver's side A/C is blowing cold air, but the passenger side is blowing warm air?

On the dual zone system there are 2 blend doors that control the temperatures. If one fails, that side can no longer control the temperature. There is something you might try first just to verify it's the actuator. Go to the Smart Junction Box under the dash on the passenger side and pull fuse 15. Leave it out for 2 minutes. Turn the ignition on for 30 seconds. Turn it off. Now put fuse 15 back in and turn the ignition on again for at least 45 seconds. Now try the controls and see if they all work or if the passenger side still doesn't change. If it doesn't then it will need to be tested and probably replaced. To see if you can tell if it's moving open the glove box and push the two release tabs and drop the box to the floor. Now look to the left on the side of the HVAC case and see if you can tell if the actuator moves when you adjust the temperature. To replace that one isn't as fun, you need to remove the upper dash panel, then the passenger side airbag module and finally you get to the actuator itself. Not a lot of fun.