There's a noise and I want to see if anyone has had it before
 

Three days ago I was just being joyful and motoring in hot and humid Virginia. I had the air conditioning blasting because of the heat. When I turned the air conditioning off and rolled the windows up in the evening I noticed a noise. It sound like the air conditioner is not all the way off, almost like its just barely on. To test this when I drive I put my nose by one of the vents and it had the musty kind of texture the air gets when the AC is on. This is my first problem with Nigel and I would like to eliminate it. Please let me know if there is anything I can do. Thanks all