Mine is also decently cold, especially when the temp is in the 80s, but once it is the 90s or approaching 100 outside it definitely seems to struggle, especially if i am in stop and go traffic and not cruising. i checked the refrigerant and it is where it should be, so that should mean no leaks. I really hate to think that it is something else, cause as far as I know, there are very few cheap AC fixes...