With the hood off, press and hold the Power/Delay Off button for three seconds. The indicator lights will light up to show the maximum CFM level of the hood.
5 indicator lights: default max. CFM (600)
4 indicator lights: max. 390 CFM
3 indicator lights: max. 290 CFM
The number of fan speed settings depends on the max CFM setting.
390 CFM = max. 4 speeds and 290 CFM = max. 3 speeds