Welcome to the Werkz.
It may be that the system needs to be regassed, some of the sensors or the compressor itself. I'd start with a AC specialist shop and get them to check the pressure in the system. Most places will do this for a fairly low price (if not free). Regassing the system (if it is low) shouldn't cost that much, and may give back the chilly air you are looking for.
Riding in style