i took it OA was resetting the discharge air setting?the static sensor and discharge air locations are critical to the AHU reacting to the swing from anything but max air.when that VFD is installed the ramping signal is going to depend on it being in a general location to track the air might want to look into its location.8 boxes on the same level as the system 1.5" is to high for such a medium application.one thing i've seen with VFDs when the space is comfortable and the boxes are floating to maintain area set points..the VFD screen should be at 25Hz to 30Hz