How to tell if an air vent is blocked?

Determining whether an indoor air vent is physically blocked or restricted involves observing localized temperature imbalances, reduced air velocity, and physical obstructions. First, visually inspect the supply register or return grille to ensure that heavy furniture, carpeting, rugs, or drapes are not covering the opening, which instantly chokes airflow. Second, feel the temperature and pressure of the air emerging from the register with your hand; if the register feels dead or produces significantly less airflow compared to other rooms while the HVAC blower is running, a blockage may exist inside the boot or duct branch. Third, remove the register cover using a screwdriver to inspect the interior boot for dropped items, toys, or dust clogs. You can troubleshoot airflow drop-offs easily. You can verify that the vent is unblocked when removing obstructions or clearing dust allows strong, forceful air to circulate freely into the room.