this morning i start my car and from the dash right behind the ac/heater vents it sounds like.. there is this loud ticking sound like "click click click click click " and its only happening if my cool air/warm air control is all the way cold.. if i turn it up just a lil warmer, not even much just as long as its not all the way cold it stops...anyone know what this is or why its happening?? thanks for the help