As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW INFLIGHT - LEFT AND RIGHT AIR CONDITION PACKS INOPERATIVE. UNABLE TO PRESSURIZE AIRCRAFT. RETURNED TO DFW AND LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE FOR EVALUATION. REPLACED LEFT FLOW CONTROL VALVE. SYSTEM GROUND CHECKED NORMAL OPERATION.