What was found
PHX - FLT 1172 - AFTER TAKEOFF PHX DURING CLIMB-OUT, UNABLE TO PRESSURIZE A/C IN EITHER AUTO OR MANUAL MODE. ACCOMP EMERGENCY DESCENT AND ALL PAX OXYGEN MASKS SUCCESSFULLY DEPLOYED. A/C RETURNED TO PHX AND LANDED W/O INCIDENT. REPLACED NR 1 PRESSURIZATION CONTROLLER AND GROUND CONTROL RELAYS R2-4 AND R2-106. SYSTEM GROUND CHECKED NORMAL OPERATION. A/C MAINTENANCE FERRY PHX/TUL. RESTOWED ALL PAX OXYGEN MASKS AND SERVICED PAX OXYGEN SYS. ACCOMPLISHED FUNCTIONAL CHECK FLIGHT AND PRESSURIZATION PROBLEM REPEATED. REPLACED OUTFLOW VALVE ACTUATOR. SYSTEM GROUND CHECKED NORMAL OPS. ACCOMP FUNCTIONAL CHECK/FERRY FLIGHT WITH NO DEFECTS FOUND. SYS OPS CHECKED NORMAL. (M)