Hooking up hood fans to ballast

[Laddy]

I'd like to hook up two 4" in my hood to remove the residual heat from the VHOs. Is there a way to hook them up to the ballast so when the timer goes on for the hood, the fans come on at the same time?

[BigBadBlenny]

hook them up to the timer with the lights. when the lights come on the fans do