I have 08 subruban k1500 z71 with 16k miles. When I first get in the vehicle I hear a noise like a seat is moving or a fan is running from around the nav system. The key is not in the ignition nor has it been remote started. The clicker has not been touched. I can even sit down in the drivers seat and still hear it. It goes away after I start the truck. Something is running but I have no idea what it would be. The Nav display is off but sound comes from that area or above it.. Is there some type of fan that would run? thanks