What was found
PIT-DFW - FLT 546 - AFTER TAKEOFF THE CABIN PRESSURIZATION FLOW LIGHT ILLUMINATED AND THE FLIGHT CREW WAS NTO ABLE TO STABILIZE THE CABIN PRESSURE. THE AIRCRAFT RETURNED TO THE FIELD AND LANDED WITHOUT INCIDENT. THE LANDING WEIGHT WAS 133,700 LBS. MAINTENANCE REPLACED THE LEFT AIR CONDITIONING PACK COOLING TURBINE AND THE RIGHT AIR CONDITIONING PACK WATER SEPARATOR TEMP CONTROL VALVE. AN OVERWEIGHT LANDING INSPECTINO WAS PERFORMED. (M)