As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PBI - FLT 188 - UNABLE TO PRESSURIZE ACFT AFTER TAKEOFF. FLIGHT RETURNED TO PBI WHERE LANDING WAS WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND DUCT CLAMP AND SEAL LOOSE ON AFT SIDE OF AFT PRESSURE BULKHEAD. REINSTALLED CLAMP AND SEAL. FOUND PACK VALVE ON LEFT PACK NOT OPENING. REPLACED LEFT PACK VALVE. REF USAA950404.