Welcome to the forum. There probably isn't a quick fix unless you aren't doing something right. You question doesn't provide enough information for anyone to suggest a fix. It may help if you answer the following questions.
Year of car? How did you determine the refrigerant level is full? Is the compressor clutch engaging, you should be able to hear it if you have someone turn the air on and off while listening for the click inside the engine compartment? Is the ac indicator light on?
Clifton