CRJ700 IS DISPATCHED WITH RIGHT PACK ON MEL AND RECEIVES LEFT BLEED CAUTION MESSAGE PASSING 9500 FEET IN CLIMB.

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DURING CLBOUT OF ZZZ; HAD A 'L BLEED CAUTION' MESSAGE DISPLAYED. THE FO WAS FLYING. THE ALT WAS APPROX 9500 FT AND WE WERE CLBING RAPIDLY DUE TO A LIGHT ACFT. THE R AIR CONDITIONING PACK WAS 'INOP' AND DEFERRED. THE FLT CTLS AND RADIOS WERE XFERRED TO THE FO FLYING. I (CAPT) RAN THE QRH PROC ABNORMAL. DURING THE PROC; I REALIZED WE COULD END UP SHUTTING DOWN THE ONLY OPERATIONAL AIR CONDITIONING PACK. I IMMEDIATELY REQUESTED A LEVELOFF AT 15000 FT. AT THIS POINT; I HAD THE FO BACK ME UP ON THE QRH AND TO VERIFY THE CORRECT PROC WAS BEING PERFORMED. ALSO TO CONCUR THAT ONCE THE PROC WAS COMPLETED; WE WOULD HAVE TO DSND TO 10000 FT OR BELOW. THE FO AND I BOTH AGREED AND PREPARED FOR DSCNT. I TRIED TO CALL OPS WITH NO ANSWER; AND MADE 1 CALL ON COMMERCIAL RADIO BUT THEY WERE TOO BUSY WITH A MEDICAL ISSUE TO ANSWER. I MADE THE DECISION; WITH THE FO'S AGREEMENT; TO RETURN TO ZZZ. WE WERE APPROX 40-45 MI OUT OF ZZZ. ATC GAVE US AN IMMEDIATE DSCNT TO 6000 FT AND DIRECT TO ZZZ. QRH PROC ABNORMAL WAS COMPLETED AS WELL AS UNPRESSURIZED FLT PROCS. THE CABIN ALT WAS NOT A FACTOR AS THE CABIN CLB RATE ONLY INCREASED TO 1100 FPM AND A SAFE ALT WAS ACHIEVED QUICKLY BEFORE CABIN ALT INCREASED BEYOND LIMITS. A NORMAL APCH AND LNDG WAS MADE ON RWY 27. DURING THE EVENT; THE FLT ATTENDANTS AS WELL AS PAX WERE BRIEFED ON THE AIR TURN-BACK. ATC WAS ADVISED OF THE SITUATION. NO EMER WAS DECLARED. ON THE GND; MAINT WAS NOTIFIED AS WELL AS DISPATCH AND MGMNT. THE SAFEST RTE WAS FOLLOWED BY MAKING A DSCNT AND RETURNING TO THE ARPT. THE EVENT OCCURRED BY HAVING A PREVIOUSLY DEFERRED AIR CONDITIONING PACK AND HAVING THE L BLEED CAUTION MESSAGE DISPLAYED. DUE TO THE CHKLIST PROCS; THE OPERATIONAL PACK WAS ORDERED TO BE TURNED OFF. SUBSEQUENTLY; CREATING A DSCNT TO 10000 FT OR BELOW. MORE 'CLEARER' QRH PROCS THAT WILL ASSIST YOU OUT OF COMPOUNDING FAILURES. MORE FAMILIARIZATION OF QRH PROCS OUTCOME COULD HAVE PREDICTED AN EARLIER LEVELOFF. KNOWING WHAT OUTCOME/POS THE QRH WOULD LEAVE YOU IN ONCE YOU HAVE A PROB. THIS WAS A COMPOUND PROB THE ACFT WAS PUT IN BY QRH PROCS. THE QRH ABNORMAL ASSUMED THAT YOU HAD 2 OPERATIONAL PACKS AT THE TIME OF THE EVENT. IT GAVE NO GUIDANCE ON ALREADY HAVING AN INOP AIR CONDITIONING PACK. ONLY COMMON SENSE; LOGIC; AND JUDGEMENT WAS LEFT AFTER BEING IN THIS SITUATION.