A/c run's and cool's but very low air flow?

While running a/c you can feel the change from defrost, floor, regular vent's etc. So vacuum switch working to move flow. But airflow seem's to be blocked and very low pressure from vents. Is there a filter somewhere?? Do I maybe need to clean evap coil? I do hvacr, but never on vehicles. 2003 Ram 1500 sport truck. Better yet how do I get this thing apart so I can get my air flow path cleaned and real air flow back????