I attempted to add refrigerant to my 2006 diesel 2500 and what appears as the low side AC service port is too large for the standard size AC service port coupler that has been used on several other vehicle makes for the low side service port. The port I am referencing on my engine sets on the left front and is the larger line service port. I called Dodge and they said all their service ports on low side are standard size. I have either been trying to couple to the wrong port (which there are only two for AC one large and one small) or something goofy exists on my truck. Does anyone know for sure exactly where the low side AC service port is located on a 2006 Ram diesel 2500?