What was found
PHX/SJC - FLT 2886 - AIR TURNBACK. UNABLE TO PRESSURIZE AIRCRAFT WITH SINGLE PACK ON CLIMB-OUT. BLEED AIR LEAK UNDER BLOW-OUT DOOR NR 1, ENGINE NR 1 KRUGER FLAP AT DUCT CLAMP. RETORQUED CLAMP.4 REMOVED AND REPLACED NR 2 ENGINE PRE-COOLER VALVE PER MM 36-00-00. REMOVED AND REPLACED NR 1 ENGINE 13TH STAGE REGULATOR PER MM 21-11-31. CABIN AIR LEAK AFT LEFT FUSELAGE AT LAP JOINT 2 PLACES ADJACENT TO PORTABLE WATER SERVICE PANEL. REMOVED PREVIOUS REPAIR, REPAIRED PER SRM 53-30-3 F. 16. E/E COOLING EXHAUST VALVE NOT CLOSING ALLTHE WAY. REMOVED AND REPLACED COOLING EXHAUST VALVE. REFERENCE: OPERATOR CONTROL NR 96ZZZX3992. (X)