As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLYING AT 450 FROM MMUN TO ABQ THE CABIN ALTITUDE STARTED CLIMBING AND COULD NOT BE STOPPED, THE CREW STARTED A DESCENT TO 270 AND LANDED IN ELP. A FUNCTIONAL TEST OF THE PRESSURIZATION SYSTEM AND A CABIN LEAK RATE CHECK WERE COMPLETED. THE PROBLEM COULD NOT BE DUPLICATED ON THE GROUND.