First, Congratulations on your new coach and welcome to the forum!!!
Under the roof cover in the coach is a divider that seperates the intake from the exhaust, if it is dislodged you won't get good airflow anywhere.
If you have a Coleman AC remove the filters on each side, you will see 4 screws, remove them and the cover will come down. Check the divider to make sure it's firmly in place. If the divider is good then you have a blocked duct and need to return to the dealer.
Motorhome AC ducts aren't the best in the world and even if everything is ok you still may not get good airflow. Also make sure the fan speed is set to high.
Dave & Myra
One day your life will flash before your eyes,
make sure it's worth watching!