As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ON THE GROUND, WHEN BLEEDS SELECTED ON, THE AIRCRAFT BEGINS TO PRESSURIZED AT MINUS 2000 FPM, THE SAME OCCURS WHEN PRESSURIZATION SELECTED TO DUMP. THE AIRCRAFT WAS BROUGHT INTO THE HANGER FOR FURTHER TROUBLESHOOTING. MTC REPLACED THE CABIN AIR CONTROLLER AND TESTED WITH NO FURTHER FAULT NOTED. THE AIRCRAFT RETURN TO SERVICE.