FLT CREW OF MD88 FAIL TO PLACE PRESSURIZATION SYS IN AUTO PER CHKLIST AND ENCOUNTER PRESSURIZATION ANOMALIES DURING CLB WHICH FORCE A RETURN TO DEP STATION. INCOMPLETE LAST MIN MAINT CONTRIBUTED.

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I WAS CAPT AND THE PNF ON A FLT FROM CVG. WE WERE DELAYED IN BOARDING THE ACFT BECAUSE MAINT WAS ON BOARD. NORMAL PREFLT WAS CONDUCTED AND BEFORE TKOF CHKLIST WAS COMPLETED. CONDITIONS WERE LIGHT RAIN; VISIBILITY APPROX 2 MI; 2 DEGS CELSIUS WITH POSSIBLE ICING CONDITIONS. THE REDUCED THRUST TKOF WAS RWY HDG TO 6000 FT. AS WE WERE CLBING TO 6000 FT; I NOTICED LIGHT RIME ICING. THE ENG ANTI-ICE HAD BEEN ON FOR TKOF; SO I TURNED ON AIR FOIL ANTI-ICING. FOR THAT REASON; THE AFTER TKOF CHKLIST HAD NOT YET BEEN COMPLETED. WE WERE THEN CLRED TO CLB TO 13000 FT. AS THE ACFT BEGAN TO CLB; THE AFT FLT ATTENDANT CALLED TO RPT A LOUD SQUEAL AROUND THE AFT GALLEY. I TOLD THE FO TO LEVEL OFF. AT ABOUT THE SAME TIME; WE WERE PASSING 10000 FT AND THE CABIN ALT AURAL VOCAL SOUNDED. I INSTRUCTED THE FO TO BEGIN A GRADUAL DSCNT. IN THE DSCNT TO 8000 FT; WE NOTICED THE CABIN ALT CTL SELECTOR WAS IN THE MANUAL POS. THE CABIN ALT CTL SELECTOR WAS PLACED IN AUTO TO TRY TO GET CTL OF THE CABIN PRESSURIZATION. THE CABIN FOLLOWED OUR DSCNT AND DID NOT PRESSURIZE IN THE AUTO MODE. I DECIDED TO RETURN TO CVG AND HAVE MAINT CHK THE ACFT RATHER THAN CONTINUE. NO EMER WAS DECLARED. LNDG AND TAXI TO THE GATE WERE UNEVENTFUL. WE SUBSEQUENTLY CHANGED ACFT AND PROCEEDED TO PWM. CONTRIBUTING FACTORS: 1) FATIGUE: A REDUCED LAYOVER IN ATL THE NIGHT BEFORE INTO A LONG DAY OF DEALING WITH WX. THIS WAS A FACTOR IN MISSING THE CHK OF THE CTLR DURING PREFLT. 2) THE PRESSURE TO STAY ON SCHEDULE AFTER RECEIVING THE ACFT LATE DURING PREFLT. 3) SET UP BY MAINT; THE ACFT HAD BEEN PRESSURIZED FOR A MAINT CHK. THE CTLR WAS LEFT IN THE MANUAL MODE FULL OPEN. NIGHT LOOKING AT THE CTLR THE POS OF THE VALVE IS THE SAME AS YOU WOULD NORMALLY FIND IN AUTO MODE. SUPPLEMENTAL INFO FROM ACN 647406: THE PNF WAS OVERLY CONCERNED ABOUT ICING AND FAILED TO NOTICE THE CABIN PRESSURE CLBING.