As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLE - FLT 3618 - THE CREW REPORTED AFTER TAKEOFF, THE PRESSURIZATION WAS UNCONTROLLABLE IN BOTH AUTO AND MANUAL MODES. THE AIRCRAFT RETURNED TO CLEVELAND WITHOUT FURTHER INCIDENT. MAINTENANCE PERFORMED OPERATIONAL CHECKS OF THE PRESSURIZATION SYSTEM IAW EMB-120 MM 21-30-00. NO DEFECTS WERE NOTED. THE AIRCRAFT WAS RELEASED TO SERVICE. (X)