2008 Dodge Ram 2500 Pickup Owner Manual - Page 270

268 UNDERSTANDING YOUR INSTRUMENT PANEL Circulation The cab is designed with features to promote outside air circulation. There are grilles in the cab back panel. These are air exhausters that provide the means for regular exchange of cab air. Side window demisters direct airflow specifically to the window glass to help prevent interior fogging of the glass. They are located in the extreme outside upper edges of the instrument panel. The demisters also provide extra air ducts for circulation. They are in operation whenever the Floor, Mix or Defrost modes are in use. NOTE: When you turn off the engine you may hear a hissing sound from under the hood for a short period of time. This is a normal condition that occurs if the air conditioning system has been on. It is not an indication of a problem with the air conditioning system. Operating Tips Fast Cooldown For a fast cooldown, turn the blower fan rotary knob to the extreme right position, turn the mode control to the panel fresh position, press the snowflake button to turn on the air conditioning, and drive with the windows open for the first few minutes. Once the hot air has been expelled, close the windows and press the recirculation pushbutton, on dual-zone control, or switch the mode from panel/fresh to panel/recirculate on single-zone control. When a comfortable condition has been reached, choose a mode position and adjust the temperature control slide and blower speed as necessary to maintain comfort. For high humidity conditions it may be necessary to remain in the Recirculation mode to maintain comfort.