I couldn't find a blend door re-learn procedure for your car but on my Tahoe it was simple as removing the fuses, waiting a minute, re-install, and start it up. Lasted for a few years until I eventually had to replace them.
My wifes 2012 CTS had the same issue. Cold on the driver's side and back vents but regular, not cold on the passenger side. I changed the blend door actuator myself on the passenger side hoping it would fix it but it didn't. I read somewhere that it could be low on freon. So I found a deal on Groupon for $69. I had it serviced, they evacuated and recharged the system and it has been working great ever since. Hope this helps anyone in this situation.