As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE EN ROUTE TO CLARKSBURG, THE LEFT PACK OVERHEATED. THE FLIGHT CREW WAS INSTRUCTED TO RETURN TO THE FIELD. THE AIRCRAFT LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE INSPECTED AND REPLACED THE FLOW CONTROL AND SHUT OFF VALVE IN ACCORDANCE WITH DORNIER MAINTENANCE MANUAL 21-61-00. OPERATIONAL CHECKS WERE PERFORMED AND THE AIRCRAFT WAS RELEASED FOR SERVICE.