When the car starts it takes a while to cool. When in traffic and sitting idle the car temprature goes up. When you press the gas after a few seconds the car begins to cool again. Never really getting cold. Check the freon level to see if it needs to be recharge, level is fine. Compressor is clear and the fan is blowing.
My AC only cools when I am accelerating. Sitting idle the temperature rises on 2008 Volvo XC90
Wrap your conditioning Lines with foam thermo tubing. Similar to vapor lock but quite the opposite. Also try using a cooler thermastat