2009 Dodge Ram 3500 Pickup Owner Manual - Page 242

240 UNDERSTANDING YOUR INSTRUMENT PANEL 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. To remove frost from the side windows, it is best to use the full defrost mode. 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. Air Conditioning with Dual Zone Temperature Control - If Equipped With the Dual Zone Temperature Control System, each front seat occupant can independently control the temperature of air coming from the outlets on their side of the vehicle. Dual Zone Control Head Air Conditioning and Heating Operation To turn on the Air Conditioning, set the fan control at any speed and press the snowflake button located on the control panel. Conditioned air will be directed through the outlets selected by the mode control. A light in the snowflake button shows that the air conditioning is on. Press the button a second time to turn the air conditioning off.