What was found
CREW REPORTED SMOKE IN COCKPIT (NO FIRE) WHILE AT GATE IN CLT. PASSENGERS WERE DEPLANED THRU MAIN CABIN DOOR WITHOUT INCIDENT AND MAINTENANCE WAS CALLED TO AIRCRAFT. RIGHT AC PACK WAS FOUND TO BE THE CAUSE. 12/27/20: DEFERRED RT PACK, IAW CRJ-900 MEL 21-51-01-2 CAT-C. VERIFIED RAM AIR SOV IS OPERATIVE. NO M-FUNCTION REQUIRED. 12/29/20: FOUND RT AIR CYCLE MACHINE TO BE INOPERATIVE IN AUTO AND MANUAL MODE. REMOVED AND REPLACED RT AIR CYCLE MACHINE, IAW CRJ 700 AMM 21-51-08-000/400-801. OPERATIONS CHECK GOOD, LEAK CHECK GOOD, THIS CLEARS MEL.