2004 Silverado extended cab - manual (driver/passenger) heat/air/vent controls Is there an adjustable point for the heat/cold? When using the vent (non/ac) the incoming air is warmer than the outside when the slider is all the way down (cold). I'm thinking that it needs to be adjusted so that the heat is totally turned off. Where does the cold/hot slider wire control terminate? and is it adjustable?