What was found
DURING CRUISE THE FLIGHT CREW REPORTED THE AUTO AND MANUAL PRESSURIZATION SYSTEMS WERE INOP AND THE AIRCRAFT DIVERTED TO BUF. MAINTENANCE DEFERRED THE AUTO AND MANUAL PRESSURIZATION SYSTEMS AND THE AIRCRAFT WAS RELEASED FOR SERVICE. THE AIRCRAFT THEN FLEW TO CLE WHERE THE FAULT WAS FURTHER TROUBLESHOT. IN CLE THE CABIN PRESSURE ACQUISITION MODULE WAS REPLACED ALONG WITH THE AUTO PRESSURE CONTROLLER WITH NO FIX. UPON FURTHER TROUBLESHOOTING THE GROUND AIR CONDITIONING CHECK VALVE WAS MISSING. THE CHECK VALVE WAS REPLACED WITH NO FURTHER DEFECTS NOTED.