FLC OF A DC9-30 RETURNED TO LAND AFTER EXPERIENCING DIFFICULTY PRESSURIZING THE ACFT DURING DEP CLB.

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WHILE PERFORMING THE CLB CHKLIST; I NOTICED THE CABIN RATE OF CLB WAS ZERO; DIFFERENTIAL 3.0 AND CABIN ALT 8500 FT; WHILE ACFT WAS PASSING 13000 FT MSL. WE LEVELED AT 15000 FT WHILE I RAN THE CHKLIST FOR CABIN PRESSURIZATION FAILURE IN AUTO. PULLING AND RESETTING CIRCUIT BREAKERS DID NOT HELP AND USING THE MANUAL PROC WAS DIFFICULT OR IMPOSSIBLE DUE TO FLUCTUATIONS IN PRESSURE THAT COULD NOT BE CTLED. AFTER TALKING TO DISPATCH AND MAINT CTL; WE DECIDED TO RETURN TO DTW SINCE WE COULD NOT GO ON TO RIC AT LOW ALT. WE WERE ABLE TO DSND GRADUALLY BACK INTO DTW AND USE THE MANUAL PRESSURIZATION PROCS TO DSND THE CABIN FOR LNDG. THANKS TO ZOB AND DETROIT APCH FOR THEIR ASSISTANCE. MY FO DID AN OUTSTANDING JOB OF FLYING; COORDINATING WITH ATC AND KEEPING ME UPDATED DURING THE ENTIRE EVENT. USING THE MANUAL PRESSURIZATION WAS WORK INTENSIVE -- THAT'S ABOUT ALL. I HAD TIME TO DO FOR THE ENTIRE DSCNT; SO A GOOD COPLT WAS EXTREMELY NECESSARY IN THIS SIT. THE NEXT DAY; I CALLED OUR MAINT CTL AND LEARNED THAT THE R AIR CONDITIONING PACK HAD A LEAKING SEAL AND THE PRESSURIZATION CONTROLLER WAS BAD AND WAS REPLACED ALSO.