What was found
IAH - FLT 0108 - THE AIRCRAFT STARTED LOSING PRESSURE AT 37,000 FEET WITH DE-ICING ON, AND OXYGEN MASKS WERE DROPPED MANUALLY. CREW ATTEMPTED SECONDARY WHICH INDICATED FAILURE, SO SWITCHED BACK TO PRIMARY. AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE OBSERVED SEVERAL OXYGEN MASKS HAD NOT DEPLOYED. BOTH LEFT AND RIGHT WATER SEPARATOR PRESSURE RELIEF PLUNGERS WERE FOUND FROZEN SHUT UPON INSPECTION OF AIR CONDITIONING SYSTEM. BOTH WATER SEPARATOR ASSEMBLIES REMOVED AND REPLACED. MASK RELEASE SOLENOID AT AFT GALLEY ATTENDANT SEAT FOUND SHORTED. SOLENOID REPLACED. THE USED OXYGEN GENERATORS ALSO REPLACED. ACFT PRESSURIZATION CHKS AND FUNCTIONAL TEST OF OXYGEN SYSTEM WERE GOOD. (X)