To be absolutely certain:
* Consult your vehicle's repair manual: This is the most reliable source for the exact location of the low-side port.
* Look for a service diagram: Many online auto parts stores will have diagrams available if you search for "2001 Dodge Ram AC system diagram."
* Check with a qualified mechanic: A mechanic will be able to quickly identify the ports for you.
Caution: Working on an AC system involves refrigerants that can be harmful. If you're not experienced with AC system repair, it's best to leave it to a professional.