Thanks all, Yes the larger line is always suction because it carries the gas ( which requires more volume) back to the compressor while the high side or liquid line as it is called has liquid refrigerant which boils off in the evaporator as it goes through a expansion valve, cap tube or an orfice which in turns causes a pressure differential. As the refrigerant boils off it is similar to when you put water on your skin in hot weaher and the evporation creates cooling.
Have worked on Ac or refrigeratuion system all the way to units capable to provide 100s of tons of cooling.
Whats bad, I know I charged before when I R&R engine---must have something to do with Age>