What was found
ON TAKEOFF ROLL, CREW RECEIVE CHIME FROM F/A. REJECT TAKEOFF JUST UNDER 80KTS. F/A ADVISE SMOKE IN CABIN. CREW TAXI OFF RUNWAY TO TAXIWAY D AND EVACUATE THE AIRCRAFT. 64 PAX ON BOARD. OVERWING EMERGENCY DOORS PULLED BUT PAX EVACUATE OUT MAIN CABIN DOOR AND TAKEN TO GRASS AREA ALONGSIDE TAXIWAY. NO INJURIES NOTED. / PERFORMED OPS TEST OF AIR CONDITIONING DISTRIBUTION SYSTEM IAW CRJ900 AMM 21-51-00-710-801. DURING OPS TEST, FOUND RH ACM CEASED CAUSING SMOKE IN THE CABIN. REMOVED AND REPLACED RH ACM IAW CRJ 900 AMM 21-51-08-000/400-801-A01. OPS CHECK AND LEAK CHECK GOOD. NO SMOKE OR ODOR DETECTED.