so i replaced the metal with rubber fittings on the compressor and i have recharged the system...it works great comes out nice and cold, but id say like 15 mins into a trip it gets warmer, still blows "coolish" air but not as cold....and then say the next day when i turn it on again it will do the same...cold...then get warmer, i recharged but i only used one small can of r134 did i not use enough? or is there another problem?

 

did you use a vaccum pump to create a vaccum before you recharged the system? if not thats probably your problem.