If you mean the light on the top or side of the Power Nozzle, yes, it should be on for most uses. You can disengage the belt for other uses. The green light illuminates when the belt is turning the brush roll. So, you see, the green light functions to confirm to you that the brush roll is spinning. For carpet, you would want the brush roll spinning. When I vacuum my comforter or sofa, I don't have the belt engaged because I don't want the roller to grab up my fabric. For that use, the green light is not illuminated.