How do I get rid of birds living in an air vent?
Go rent a shopvac, and gently suck them up.  Then when you return the shopvac, they will safely place the birds outside of the business for no additional charge (as long as you don't tell them about it.)

Just kidding, if they have eggs right now then you will just have to wait.  If they don't then there is a plethora of things you can do.  The netting is fine, or remove the nest while it is away.