I have a central cooling system that has stopped cooling efficiently. The air it blows is very humid and does not do well when temps are over 95. I change the filters out in the house every 3 months. The rest of the system is up in the attic. I had someone come out they told me my system was fine and pressures as well as coolant were good. Any suggestions?

It kind of sounds like system may be pulling very hot air in from the attic through the return, check to make sure there are no holes or seporated ductwork in attic

Unless your system is tight and attic well ventilated, your heat load from ambient temps will tax your system. Does it work OK at night?