So the AC is working, is it just not as cold as you'd like it to be? If that's the case, I would start by putting a thermometer into the vents with the A/C on full blast and see what the temperature the A/C is blowing at and compare that to what the manufacturer says is the temp it should be blowing at. If you're in an area with extreme heat waves, there might be nothing technically wrong with your A/C. It just might not be able to keep up with the extreme heat, which is a common problem with lots of cars.