Chrysler Repair: low pressure valve a/c on 3.3 1999 caravan, auto parts store, pressure valve

Question
I want to add 1 can of 134  .  There are 2 of 3 valves possible.  where is its location?

appreciate response

Answer
there are only 2 and u cant add freon on the high side because the stuff u get at an auto parts store is only low side. so u are down to the only connector that the gauge will attach onto. The low side is small and the high side is bigger.If u live in the Atlanta area and find a leak I am AC certified in repairs.