@punk
i think u r talking about the pajero's heater light...man the best time to start is when the light turns green...it doesnt really matter in summers n u can start even when its red but the best time is when it is green.
@toyopat
man 30 sec is the time when it completely turns off..it has nothing to do with the heater time...the real heater's time is 4-5 sec(as he mentioned) after which the light turns from red to green.