The car seems to heat up normally, but it just keeps on heating up until it's just about in the red and the stage two fan comes on and stays on. Even on a long run at about 70mph for 20 minutes the temps hardly dropped at all and the air through the vents, even if I put it all the way to what should be the hottest is merely warm. is there some sort of heat exchanger that could be knackered? A leak somewhere?