Recharge AC on a 2000 LS

Has any body had success in recharging the AC system with the canned R134a?, can you tell me which inlet is high and low? I know there is one under the hood pass side and one below on the drivers side!, I had the lines replaced ( corroded and pitted at the joints ) last summer to the tune of a $1000! recharged, filled with dye, checked with sniffer and was perfect, stayed ice cold until this monday, now will only go down to 65F with the temp gauge in the vent and system on full tilt!,temp should go down to 58F,I suppose is it possible that a new leak has developed, but you'd think a 2000 with 80K should hold together for at least 150K, has anyone tried that leak sealer that is available?, any help is great, thanks all.

The A/C service port is located on the condensor under a plastic shield on the drivers side of the car. You'll have to jack it up to get there. Let me know if you have any success. Mine level reads fine but still doesn't seem as cool as it should be.