Today I had my first real experience driving in a lot of snow. It was somewhat unusual in that it was snowing heavily and very cold at about -15C. I had the heated wipers on the entire time and also had the Windshield defroster going pretty much the whole time. But my wipers still got icy and didn't work very well. Shouldn't the heater wiper blades stop this from happening? Or is this just an extreme case with bitter cold and heavy snow at the same time that the car just couldn't cope with?