Ive got to put some freon in my GF's Durango, but I have no idea which port is the low pressure side that I can attach my handy dandy freon can adapter to. I tried looking it up on google, and just go nowhere with that so I figured id ask it here.
In this picture, which is the port I need to hook to? The one closest to the radiator or the one closest to the firewall ?

 

The easiest way to check is check the bigger of the two lines coming from the A/C compressor. The bigger line should be the low pressure low temperature line. The high pressure line will be hot and low pressure line will be cold. Trace back starting from compressor until you find the service port on the low side.

 

the low pressure is the closest to the radiator. also i think that is the only one the recharger will adaptor will fit on. (never tried putting on the high pressure side)