It started with my AC not working while I was at a stand still, say in traffic. It would then work when I got back on the gas. But about a week ago air just stopped coming out of all the vents and would only come out of the defroster vents. No matter what setting it's on, or speed, it all comes out the defrost vents. So if I turn the AC on it will eventually blow cool air through the defroster vents while I'm driving, if I come to a stand still the AC air coming through the defroster vents will not be as cool, more musty. This is what it would do through the 4 dash vents before it stopped all together. What could be the deal?thx.