As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RT PACK WAS UNABLE TO HOLD PRESSURIZATION AT FL310. FLIGHT CREW DESCENDED TO FL270 AND WAS ABLE TO HOLD PRESSURIZATION. COMPLIED WITH QRH, NO HELP. MAINTENANCE FOUND RT PACK TEMPERATURE CONTROL VALVE BOOT OFF. SECURED BOOT. PERFORMED HEALTH CHECK. OPERATIONS GOOD.