Check to make sure their isn't a tiny switch under the power button or somewhere else near the power button. Some people(like me) have installed Thor's heater switch so the heat doesn't turn on(the heating loop, below 60? degrees) otherwise without it anytime you turn on the fan below 60f?, even with heat set low, the heating loop will turn on. Also push the blue button on your screen and then energy use? it will show any power draw from the climate control, if the heater is on it will draw up to 6kw, if not it will be near zero. If the heater itself is bad, that's real bad! it can be a very expensive fix and might not be worth fixing for a vehicle that old.