Did it blow cold straight after the refilling? If it did, the most probable cause would be a leakage.
Few weeks ago I also re-gased my system for two times, both times it was checked for leaks with vacuum pump and both times it got empty few days after refilling. The vacuum check readings were perfectly fine though. After a thorough investigation we discovered a small plastic sealing at the bottom of the climate radiator which leaked the gas under the heavy pressure. But during the vacuum test it was pulled strongly against the radiator body and showed no sign of leakage. As most of the leakage testing is done by the vacuum pumps it might be likely scenario...
Don't know if all 9K's come with that idiotic plastic sealing tho, but replacing it with a 9mm bolt would be a good idea, at least helped me
cheers Lasse