How to make more air come out of vents?

To increase airflow coming out of your residential supply vents, you need to systematically eliminate restrictions across your heating and cooling system. First, replace your indoor air filter, as a clogged filter is the most common cause of restricted airflow and high static pressure. Second, verify that all supply registers and return grilles throughout the house are fully open, unobstructed by furniture, and clean. Third, inspect accessible basement, crawlspace, or attic ductwork for disconnected joints, crushed flexible runs, or closed balancing dampers that restrict volumetric flow. Fourth, consider clearing debris from your indoor evaporator coil or upgrading your blower motor settings. You can troubleshoot airflow velocity using your hand or an anemometer. You can verify that your corrective actions were successful when powerful, steady air rushes out of every supply vent.