I hse a 2003 3500 that has been doing this for years. Check your freon charge. I have the dual control and keep a thermometer in the air duct. When the outlet air gets below 40 degrees F. I add a little heat to one side of the systel to keep the evaporator from freezing. I usually have to add a little freon 134A every couple years. Dodge runs a evaporator noisture sensor to cycle the compressor. If the evaporator freezes there is no moisture for the sensor to read. The low freon charge is taking the low side head pressure below the freezing point for R134A.
