As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EXPERIENCED PRESSURIZATION PROBLEM. CABIN ALTITUDE COULD NOT BE CONTROLLED MANUALLY, O2 MASK DEPLOYED. RETURNED TO ATL. REMOVED AND REPLACED HOSE ASSEMBLY FOR LOWER WATER SEPARATOR DUCT ON RIGHT PACK. REMOVED AND REPLACED HOSE ASSEMBLY FOR UPPER AIR CONDITIONING TEMPERATURE CONTROL DUCT ON RIGHT PACK IAW DC9 MM 21-20, 21-60.