What was found
DURING CLIMB JUST BEFORE FL190 CREW NOTICED A WHITE SMOKE FILLING THE CABIN. CHECK LIST FOLLOWED, SMOKE EVACUATION PROCEDURE, EMERGENCY DESCENT WAS PERFORMED, EMERGENCY DECLARED, AND UNSCHEDULED LANDING AT ALTERNATE AIRPORT PERFORMED WITHOUT INCIDENT. MAINTENANCE EVALUATION FOUND NR 1 AIR CYCLE MACHINE AS CAUSE AND SOURCE OF WHITE SMOKE. ACM WAS REMOVED AND REPLACED. P/N 815240-3 S/N OFF 200402017 S/N ON 200005248.