What was found
40 MINUTES INTO FLT, CABIN ALT WARNING HORN AT APPROX 9500 FT CABIN ALT. C/W CABIN ALT AND RAPID DECOMPRESSION CHECKLIST. PROCEEDED WITH QRH AND STARTED DESCENT. CABIN CLIMBING AT 100-200 FPM WITH SOME SPIKES WHERE PRESS SEEMED TO STABILIZE. ALSO NOTICED DUCT PRESSURE FLUCTUATIONS FOR BOTH PACKS BETWEEN 20-40 PSI. CONTINUED DESCENT, CABIN CONTINUED CLIMB AT A STEADY RATE OF 100-400 FPM. CABIN BEGAN TO STABILIZE AND DESCENDED TO FL220 AND CABIN ALT PRESSURIZED NORMAL. CABIN RECOVERED ON ITS OWN IN MANUAL MODE. PERFORMED EXCESSIVE CABIN PRESSURE LEAKAGE INSPECTION. PERFORMED CABIN DEPRESSURIZATION CONDITIONAL INSPECTION. PERFORMED PRESSURIZATION CONTROL SYSTEM OPS TEST. PERFORMED TROUBLESHOOTING, FOUND FAILED CABIN PRESSURE CONTROLLER, REPLACED AFT CABIN OUTFLOW VALVE, REPLACED CONNECTOR PLUG D00950, REPLACED RT 35 DEGREE VALVE CONTROLLER, REPLACED WATER SEPARATOR BYPASS VALVE, REPLACED COALESCER BAGS, REPLACED. CVR AND FDR PLACED IN QUARANTINE AND REPLACED. ALL PAX CABIN OXYGEN GENERATORS REPLACED. AFT F/A OXYGEN GENERATOR REPLACED. PASSENGER AND FA OXYGEN MASKS CLEANED AND RESTOWED. ACFT RELEASED FOR FCF. FCF FOUND SATISFACTORY.