As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - CREW REPORTED LEFT PACK WOULD NOT MAINTAIN CABIN PRESSURIZATION AND RIGHT PACK INOPERATIVE PER MEL. FLIGHT RETURNED DFW LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. REPLACED Y-DUCT THAT HAD A HOLE IN IT. SYSTEM GROUND CHECK NORMAL OPERATION.