As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 815, CLT-CUN: DURING CLIMB, CREW REPORTED FAILURE OF LEFT PACK WHILE THE RIGHT PACK WAS ALREADY ON MEL. INITIATED EMERGENCY DESCENT TO 10,000 FEET AND RETURNED TO CLT. MAINTENANCE ACTION PENDING. 12/31/07 UPDATE: MAINENANCE REPLACED THE CABIN PRESSURE CONTROLLER. NO FURTHER FAULTS.