B737-800 PRIOR TO DSCNT THE CAB ATTENDANTS RPT LAVATORY WASTE WATER VACUUM MOTOR RUNS CONTINUOUSLY WITH NO PUSH BUTTONS ACTIVATED.

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JUST PRIOR TO DSCNT; THE FLIGHT ATTENDANTS RPTED THAT THE FORWARD LAV FLUSH MOTOR HAD STARTED WITHOUT THE FLUSH BUTTON BEING DEPRESSED AND THAT IT HAD BEEN RUNNING FOR SEVERAL MINS. THEY SAID THEY WERE UNABLE TO STOP IT. WE IMMEDIATELY BEGAN LOOKING FOR THE CIRCUIT BREAKERS AND COULD NOT FIND THEM. WE ASKED THE FLIGHT ATTENDANTS TO LOOK IN THE CABIN; AND THEY COULD NOT FIND THEM. WE HAD THOUGHTS OF THE ACR Y DISASTER WITH THE SUBSEQUENT FIRE AND DIVERSION TO ZZZ. FORTUNATELY; THE MOTOR STOPPED; AND WE LANDED UNEVENTFULLY. ON SUBSEQUENT FLIGHTS; WE TRIED TO FIND THE CIRCUIT BREAKERS WITHOUT SUCCESS. PLEASE TELL ME WHERE THEY ARE. I WOULD STRONGLY SUGGEST THAT WE ADD A PROC FOR THIS EVENT AND WE ALSO ADD A CIRCUIT BREAKER LOCATION CHART. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE FLIGHT ATTENDANTS RPTED THE VACUUM WASTE WATER BLOWER WAS RUNNING AND COULD NOT BE SHUTDOWN WITH THE LAVATORY PUSH BUTTON SWITCHES. THE RPTR SAID THE FLT CREW SEARCHED FOR A CIRCUIT BREAKER BUT WERE UNABLE TO FIND ANY LABELED FOR LAVATORY BLOWER OR LAVATORY MOTOR. THE RPTR STATED THE CIRCUIT BREAKER LOCATION CHART WAS NOT FOUND IN THE COCKPIT AS IT IS NOT STANDARD COCKPIT EQUIP ANYMORE. THE RPTR SAID WHEN ON THE GND MAINT ADVISED THE BLOWER MOTOR CIRCUIT BREAKER WAS LABELED LAV VAC. THE RPTR STATED THE ELECTRICAL BUS CHARTS TO ISOLATE BUSSES ARE NOT IN THE FLT MANUAL AND SHOULD BE AS THEY ARE USEFUL TOOLS TO REMOVE POWER FROM A BUSS.