You say the light on the plug and the light on the ozonator is on... Then, the ozonator IS working. The ozonator is passive, in that it doesn't push air into the spa. It's simply a box, that produces ozone. Something else has to extract the ozone from "the box". The spa pulls air from the ozonator, usually by way of a mazzi injector. The issue you're having is most likely being caused by a faulty injector.