The heater fan in my '03 C5500 doesn't shut off when the key is turned off. I have a blizzard 8611 mounted but the problem didn't start unill several weeks after the plow was installed. Has anybody had similar problems? I wonder if I should take it to the GM dealer or the blizzard dealer. I'm sure it is a simple fix but I'd bet it's going to be hard to track down. I don't relish the thought of it being in the shop for days on end or being charged for service if it was an upfitter fault taken to the GM dealer.