As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNABLE TO CONTROL THE CABIN PRESSURIZATION. THE ACFT WAS CLIMBING THRU 37000 FT WITH A CABIN ALTITUDE OF 9500 AND A 600 FT CLIMB ON THE CABIN RATE. INSTALLED TEST BOX. ALL CHECKED GOOD. PERFORMED CONTROLLER SELF CHECK, ALL GOOD. FLOW VALVES INSPECTED, NO DEFECTS NOTED. RAN ACFT. FOUND RT FLOW CONTROL VALVE ERRATIC, REMOVED RT FLOW CONTROLL VALVE & INSTALLED EXHAUST VALVE IAW MM 21-11-10. COMPLIED WITH ALL SOURCE AND PRESSURIZATION CHECKS AND ALL CHECKED GOOD ON GROUND. LEAK CHECKED GOOD. WORK DONE IAW MM 36-11-00. .