2006 Dodge Ram 1500 Pickup Owner's Manual - Page 286

286 UNDERSTANDING YOUR INSTRUMENT PANEL Summer Operation Air conditioned vehicles must be protected with a high quality antifreeze coolant during summer to provide proper corrosion protection and to raise the boiling point of the coolant for protection against overheating. A 50 % concentration is recommended. Refer to Recommended Fluids and Genuine Parts for the proper coolant type. When using the air conditioner in extremely heavy traffic in hot weather especially when towing a trailer, additional engine cooling may be required. If this situation is encountered, operate the transmission in a lower gear to increase engine RPM, coolant flow and fan speed. When stopped in heavy traffic, it may be necessary to shift into NEUTRAL and depress the accelerator slightly for fast idle operation to increase coolant flow and fan speed. NOTE: On models equipped with Diesel engines, the idle speed will automatically increase to 1000 rpm at elevated coolant temperatures to improve engine cooling. Your air conditioning system is also equipped with an automatic recirculation system. When the system senses a heavy load or high heat conditions, it may use partial Recirculation A/C mode to provide additional comfort. Winter Operation When operating the system during the winter months, make sure the air intake, located directly in front of the windshield, is free of ice, slush, snow, or other obstructions.