What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: UPON CLIMB OUT WE EXPERIENCED A RAPID RATE OF CABIN ALTITUDE ASCENT. FLIGHT ATTENDANTS SAID A SWOOSHING NOISE COULD BE HEARD FROM THE AFT LEFT DOOR BOTTOM. AIRCRAFT AIR INTERRUPTED BACK TO AND LANDED SAFELY AT DCA. TROUBLESHOOT FINDING LEFT SWITCH PACK NUMBER 1 INOPERATIVE. REMOVED AND REPLACED AIR CONDITIONING OVERHEAD MODULE PANEL, PER 31-11-94. OPS TEST GOOD. ALSO PERFORMED PRESSURIZATION TASK 21-31-00-710-801 AND 21-31-00-700-802. SYSTEM GROUND TEST AND MANUAL MODE TEST.