What was found
PRESSURIZATION AUTO FUNCTION FAILED ON DEPARTURE. CABIN PRESSURE CLIMBED TO 2,000 FT MINUTE. SWITCHED TO STBY, CABIN RECOVERED. OK TO CONTINUE PER MEL 21-14 AND SPECIAL PROCEDURE. REPLACED MAIN (AFT) OUTFLOW VALVE, SYSTEM OPS CK'D PER M/M. TAG (P/N 987342) (S/N 711003-3) OFF, (P/N 112796) (S/N 148994) ON.