AN ACR MLG CAPT ABORTS HIS TKOF FOR A MASTER CAUTION WARNING.

Narrative

WE PUSHED BACK FROM GATE AT ONT ARPT AT AB23 AM. OAT WAS 34 DEGS F ON A CLR MORNING. WE STARTED BOTH ENGS AND CALLED FOR TAXI. WE WERE CLRED TO RWY 8R. AFTER STARTING THE TAXI; WE HAD BOTH MASTER CAUTION LIGHTS ILLUMINATE AND AN AMBER 'AIR-CONDITION' INDICATION ON ONE OF THE ANNUNCIATOR PANELS. IT WAS INDICATIVE OF A L DUCT OVERHEAT ON THE AIR-CONDITIONING PANEL. I CONTINUED TO TAXI SLOWLY AS THE FO EXECUTED THE IRREGULAR CHKLIST FOR A DUCT OVERHEAT. THE 'DUCT OVERHEAT' LIGHT EXTINGUISHED IMMEDIATELY AFTER COMPLETING THE CHKLIST. WE CONTINUED FOR TKOF. AFTER COMPLETING THE BEFORE TKOF CHKLIST AND SEATING THE FLT ATTENDANTS; WE WERE CLRED FOR TKOF. I WAS TO MAKE THE TKOF AND SELECTED TOGA. THE THROTTLES MOVED FORWARD AND THE FO ADVISED '80 KTS; THRUST SET.' AT 110 KTS; THE MASTER CAUTION LIGHTS ILLUMINATED; BUT I COULD NOT DETERMINE THE PROB (THERE WAS NOTHING ILLUMINATED ON MY ANNUNCIATOR). BECAUSE I FELT UNCOMFORTABLE; I DID NOT WANT TO CONTINUE AND ABORTED THE TKOF AT 120 KTS. OUR GROSS WT WAS 105000 LBS WITH A V1 OF 131 KTS (+2 CORRECTION FOR TEMP/ALT). THE ACFT DECELERATED WITH MAX ENERGY BRAKING IMMEDIATELY AFTER RETARDING THE THROTTLES. I ALSO SELECTED LOW RESERVE. HALFWAY THROUGH THE DECELERATION (AT 95 KTS); I DISENGAGED THE AUTOBRAKES (RTO) AND SIMULTANEOUSLY CAME OUT OF LOW REVERSE SINCE WE HAD OVER 5000 FT OF RWY LEFT AND I DIDN'T SEE THE NEED FOR MAX ENERGY BRAKING ANYMORE. THE FO INSTRUCTED THE PAX TO REMAIN SEATED. WE TURNED OFF AT HIGH SPD TXWY Q. I ASKED THE FO TO CHK THE BRAKE COOLING CHART TO VERIFY WE WEREN'T IN THE MELTDOWN ZONE. WE RECEIVED A CLRNC FROM GND CTL TO TAXI BACK TO THE GATE. WE INFORMED OPS OVER THE RADIO THAT WE WOULD NEED TO CHOCK THE ACFT IMMEDIATELY AFTER BEING RECEIVED AT THE GATE. THE MECH CAME ONBOARD AND INFORMED US AFTER WE TOLD HIM ABOUT THE DUCT OVERHEAT THAT THE R OUTBOARD TIRE NEEDED TO BE CHANGED BECAUSE IT LOST SOME RUBBER FROM THE HIGH ENERGY BRAKING. AFTER THE DUCT OVERHEAT ON TAXI-OUT; AND PRIOR TO TKOF; I SHOULD HAVE REBRIEFED THE TKOF AND TOLD MY FO TO BE PARTICULARLY ALERT FOR THE SAME PROB. IT WOULD HAVE BEEN A GOOD REMINDER FOR ME; TOO. I USUALLY DO THIS; BUT FAILED TO DO IT THAT MORNING. A GOOD NIGHT'S SLEEP ALSO HELPS ONE BE AT THEIR BEST. I STILL DON'T KNOW A RELIABLE METHOD TO GET TO SLEEP EARLY ENOUGH SO I CAN HAVE AT LEAST 7 HRS OF SLUMBER. I HAD 5 HRS OF SLEEP THAT NIGHT. A SUPPRESSION SYS; LIKE ON THE B757/767; WOULD BE EXCELLENT ON THE B737. THEN; ANY AMBER LIGHTS OR MASTER CAUTIONS WOULD BE SUPPRESSED UNTIL 400 FT AGL. 99% OF ALL HIGH SPD ABORTS WOULD BE AVOIDED. IT IS ALSO NOT MY OPERATING PHILOSOPHY TO ABORT FOR AMBER LIGHTS OR MASTER CAUTIONS. THAT MORNING; I DID. I WAS SIMPLY UNCOMFORTABLE.