What was found
DEBRIEFED CREW, DEPRESSURIZATION PROBLEM OCCURED IN CABIN PRESSURIZATION POSITION AUTO 2 MODE WHEN CLIMBING FROM 36,000 TO 38000 FEET WITH ASSOCIATED RED ALARM LIGHT. CREW SWITCHED TO AUTO 1 MODE AND PREPARED TO CONDUCT EMERGENCY DESCENT. AUTO 1 APPEARED TO OPERATE SATISFACTORY PERFORMED BITE CHECK OF CABIN PRESS CONTROLLER 2 IN FWD PIT. NO FAULTS. FWD PIT OPEN FOR CONTROLLER REPLACEMENT. REF AMM21-31-00 REMOVED AND REPLACED #2 AUTO CABIN PRESSURE CONTROLLER REF AMM 21-31-02. BITE CHECK GOOD. FOLLOWED FIM CODE 21 30 20 00 (21-30 FAULT TREE 802). NO FAULTS WERE NOTED, AUTO CABIN PRESSURE CONTROLLER #2 WAS REPLACED AS PRECUATIONARY. IPC REFERENCE # 25-71-91-21N REF LP 6750468, ACPD PRESS CONTRL SYS TEST GOOD IAW AMM 21-31-00-735-023 AND THE CAB PRESS INDICATION AND WARNING TEST GOOD IAW AMM 21-31-00-735-001. CONTROLLER, CAB OFF 19-2131-9-0004 9353 ON 19-2131-9-0004 0178 CONTROLLER, CAB OFF 19-2131-9-0004 9353 ON 0000.