What was found
FLIGHT 6482 ATL TO MDW AT ABOUT 90 KTS ACCELERATING, CREW RECEIVED AMBER -IAS- COMPARATOR MESSAGES ON THE AIRSPEED TAPES. CREW REJECTED THE TAKEOFF AND RETURNED TO GATE. MAINT CYCLED POWER AND ADSP BIT RAN OK, NO SPLIT, RESECURED BRAKE TEMP SENSOR AT RIGHT O/B BRAKE, OPS CHECK GOOD. REPEAT DISCREPANCY 03/19 FLIGHT 6459 HOU TO ATL IAS FLAG APPEARED ON BOTH PFD DURING TAKEOFF ROLL. TAKEOFF WAS ABORTED 80-90 KIAS. FLT CREW RESET A/C POWER, OCM REPORTED NO FAULT CODES FOUND, GETTING DOWNLOAD IN ATL. DOWNLOAD INDICATES NR 4 ADS PROBE AS POTENTIAL PROBLEM. REMOVED AND REPLACED NR 4 ADS PROBE. OPS CHECK GOOD.