As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED A PRESSURIZATION MALFUNCTION AND A CABIN ALTITUDE ANNUNCIATOR WHILE IN FLIGHT. THE FAULT WITH THE PRESSURIZATION SYSTEM WAS DEFERRED BY MEL 21-30-02-008 UNTIL MAINTENANCE COULD BE HAD. THE MAINTENANCE VENDOR DETERMINED THAT THE CABIN AIR CONTROLLER WAS AT FAULT AND REPLACED IT WITH AN OVERHAULED UNIT. OPS CHECKS WERE SATISFACTORY AND THE AIRCRAFT WAS RETURNED TO SERVICE.