As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLT - FLT 122 - AT FL230, CAPTAIN STATED HE LOST CABIN PRESSURIZATION. SYSTEM DID NOT AUTO SWITCH TO STANDBY. MANUAL AC WAS SELECTED AND CONTROL WAS REGAINED. FLIGHT RETURNED TO FIELD AT CLT AND LANDED WITHOUT FURTHER INCIDENT. AN EMERGENCY WAS DECLARED. MAINTENANCE REMOVED AND REPLACED THE CABIN PRESSURE CONTROLLER PER MM. SYSTEM CHECKS GOOD IN AUTO AND STANDBY. (M)