As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. EMERGENCY DECLARED. ORD-RDU FLIGHT RETURNED TO ORD ACCOUNT PRESSURIZATION ISSUES. LANDING UNEVENTFUL. REMOVED AND REPLACED LEFT AIR CONDITIONING PRESSURE REGULATOR VALVE IAW AMM 21-31-01 AND REPAIRED WIRE ON RIGHT AIR CONDITIONING PRESSURE REGULATOR VALVE CONNECTOR IAW AMM 21-00-00 (AALA201705109027). OPERATIONAL AND LEAK CHECK GOOD.