A CRJ-700 FAILED AUTO AND MANUAL PRESSURIZATION SYSTEM CHECKS DURING A MEL DEFERRAL TEST. MAINT'S INTENT WAS TO DEFER THE MANUAL SYSTEM. CAPT REFUSED AIRPLANE.

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AUTO PRESSURIZATION CTLR 2 FAILED. ZZZ MAINT MEL'ED IT UNDER 21-7. THE PROVISO REQUIRES TESTS TO BE ACCOMPLISHED PRIOR TO ENG START. THE TEST CHECKING THE MANUAL PRESSURE CONTROLLER AUTHORITY ON SOME VALVE FAILED. MAINT OPERATIONS CENTER DIRECTED ZZZ MAINT TO ASSESS THE POSSIBILITY TO MEL UNDER 21-8. AT THIS POINT; I HELPED LOCAL MAINT WITH THESE TESTS MAINLY BECAUSE THEY WERE NOT IN POSSESSION OF THE EMER CHECKLISTS WHICH ARE DESCRIBED IN THE PROVISO TEST. ONCE AGAIN THE TEST FAILED BECAUSE THE MANUAL PRESSURE CONTROLLER DID NOT HAVE AUTHORITY ON SOME OF THE VALVES. NO RELIEVE IS OFFERED BY THE MEL FOR A FAILURE OF ALL OR PART OF THE MANUAL PRESSURE CONTROLLER. I BELIEVE MEL 21-8 DOES NOT INCLUDE THE MANUAL PRESSURE CONTROLLER. IT IS ONLY FOR THE 2 AUTO CONTROLLERS. EVEN FOR AN UNPRESSURIZED FLT THE MANUAL CONTROLLER HAS TO OPERATE SINCE OTHER VALVES STILL HAVE TO BE ACTUATED LIKE THE GND VALVE AND THE EMER DEPRESSURIZATION. ALL THESE VALVES ARE ELECTRICAL MOTORS RATHER THAN VACUUM OPERATED LIKE OTHER AIRPLANES IN THE FLEET. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR SAID THE CREW ASSISTED THE LOCAL TECHNICIAN WITH THE TEST TO CONFIRM OPERATION OF THE MANUAL PRESSURIZATION SYSTEM. THE RPTR SAID WHEN DEFERRING THE AUTO PRESSURE SYSTEM; THE MEL SPECIAL PROCS REQUIRES A TEST OF THE MANUAL PRESSURIZATION SYSTEM. THE RPTR STATED THE TEST FAILED AS THE OUTFLOW VALVE COULD NOT BE CONTROLLED IN MANUAL MODE. THE RPTR SAID IT WAS THE INTENT OF MAINT OPS TO DEFER THE MANUAL MODE PRESSURIZATION SYSTEM USING THE MEL 21-8. THE RPTR STATED THE AIRPLANE WAS REFUSED AS THERE WAS NO WAY TO CONTROL CABIN PRESSURE.