The heater light on the Little Green® (for models with a heater) will light up within 30 seconds of pressing the Heater Button (model 50Y6 heater button is also the power switch), to indicate the heater is ready for use. After deactivating the heater by pressing the Heater Button, the heater light will stay lit until the heater substantially cools down (below the ready-to-use temp).
O position = Off
I position = On