This is on a 2006 F350 XLT regular cab. When I turn the electronic 4x4 knob from 2wd to 4x4 Hi, the fan will just stop blowing (whether it was set to 1,2,3,4 does not matter, it goes straight to zero-fan shuts off). Just curious why it does this, I have had the fan eventually come back on without going back to 2wd