What was found
DURING CLIMBOUT THE CREW NOTICED THAT THE CABIN ALTITUDE WAS APPROXIMATELY 10,000 FT. THE AIRCRAFT WAS LEVELED OFF AT 16,000 FT AND THE CREW DONNED THEIR OXYGEN MASKS. PASSENGER OXYGEN MASKS RELEASED WHILE ATTEMPTS WERE MADE TO ISOLATE THE PROBLEM. MANUAL PRESSURIZATION CONTROL WAS USED TO MAINTAIN CABIN PRESSURIZATION WHILE THE AIRCRAFT WAS DIVERTED TO KAPA. MAINTENANCE REPLACED THE PRESSURIZATION CONTROLLER. GROUND OPERATIONAL CHECKS OF THE PRESSURIZATION SYSTEM WERE SATISFACTORY, AND A SUCCESSFUL CHECK FLIGHT WAS PERFORMED. THE AIRCRAFT WAS RETURNED TO SERVICE.