All of the low pressure lines are the larger diameter lines. The pressure valve to add freon is close to the accumalator/ drier, which wiil be on a large line. The hose that hooks to the valve will only seat down on the correct line. It is set up to be almost fool proof!!! Of course, there are exceptions!!
1997 Black XJ Sport 4x4, 1" Shackle/coil spacer lift, Ram Brush guard w/ 6in spot lights, Smittybilt Nerf bars, Class III Hidden Hitch, Elliptical Driving Lamps, Prime Wheels#234 15x8.5, 30x9.50r15, BFG AT's, JVC CD player, Alpine V12 Amp, 1-12in RockfordFosgate Subs, 5-1/4 Rockford Fosgate component speakers in doors & sound bar, Euro-spoiler, Pacesetter Cat-Back, Optima Red Top battery, HID Headlamp Conversion, Gabriel Hijacker Air Shocks on rear axle