A B737-300 ON TAXI IN TO GATE THE FO NOTED CABIN PRESSURE AT 4 PSI. SWITCHED TO STANDBY AND CABIN DIFFERENTIAL PRESSURE INCREASED AT 2000 FPM. SWITCHED TO MANUAL TO OPEN OUTFLOW VALVE.

Narrative

ON TAXI IN FROM LNDG ON RWY 35L; AFTER TAXI-IN FLOWS WERE ACCOMPLISHED; THE CABIN BEGAN TO PRESSURIZE. I NOTED THE FLT/GND SWITCH WAS IN GND POS AND THE FIELD ELEVATION SET TO 5430 FT. HOWEVER; THE OUTFLOW VALVE WAS FULLY CLOSED. THE CABIN PRESSURE WAS APPROX 4 PSI DIFFERENTIAL AND CLBING AT 2000 FPM. I SWITCHED THE PRESSURIZATION PANEL TO 'STANDBY' WITH NO CHANGE IN OUTFLOW VALVE POS. I THEN SWITCHED TO MANUAL AC AND WAS ABLE TO MOVE THE OUTFLOW VALVE TO FULL OPEN AND THE CABIN DEPRESSURIZED. AFTER SHUTDOWN; I CONTACTED MAINT BY RADIO; EXPLAINED THIS PROB AND ASKED FOR A MECH TO MEET THE ACFT. I ALSO WROTE UP A DESCRIPTION OF THIS PROB IN ACARS AND SUBMITTED IT. I MET WITH THE MECH SENT BY MAINT; THEN LEFT THE COCKPIT TO MAKE ROOM FOR THE NEXT CREW. I ALSO EXPLAINED THE PROB TO THE OUTBOUND FO. IT APPEARS THE ACARS WRITE-UP WAS NOT RECEIVED BY MAINT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE FO ADVISED MAINT OF THE PROB AND THE OUTBOUND CREW WAS ALSO BRIEFED. THE RPTR IS UNSURE OF THE MAINT ACTION BUT IS CERTAIN THE CTL PANEL WAS CORRECTLY PROGRAMMED.