How do you set airflow?

For the PSC motor (standard single speed) CFM is initially set using the blower restrictor plate on the outlet of the blower. You move it up or down to set motor amperage listed on the side of the blower module. CFM and mass flow (pounds of air per minute) are related. As the cfm goes up so does the mass flow and amperage.

With the ECM motor (variable speed) the motor control board has 2 factory settings which can be custom set with a laptop. There are 6 different speeds available.