As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PRESSURIZATION LOSS DURING CRUISE. EMERGENCY DESCENT ACCOMPLISHED & O2 MASKS DEPLOYED ON DESCENT. DESCENDING ON THE ARRIVAL CABIN ALT WARNING HORN ALONG WITH CABIN ALT WARNING LIGHT WERE ACTIVE. EMERGENCY DECLARED FLIGHT LANDED MEX WITHOUT INCIDENT. REPLACED LEFT PACK/ZONE TEMPERATURE CONTROLLER. SYSTEM GROUND CHECKED NORMAL OPERATION.