Air temperature from the a/c vents can vary depending upon many factors. Humidity level, ambient temperature, engine temperature, etc. But usually, vent temp should be somewhere between 47F & 40F. This should be tested with fan speed on high and your vent set to recirculate. Your vent temp will be colder if you are actually driving the veh. The more air you can move across the condenser (thats the thing in front of the radiator) the cooler your a/c will be.
Source: GM Certified Technician