How Can You Tell if an HVAC Damper is Open or Closed?

An open damper plate will exhibit a gap, while a closed damper has a plate that covers the duct, effectively blocking airflow. A manual lever-controlled damper means your damper is currently open; an automatic one will have an indicator on the motor to tell you if it's open or not. Some models have LED lights that change color to indicate position — green when it's fully opened and red when it's closed.