What was found
(CAN) PILOT REPORTED, DURING PREFLIGHT. THEY STARTED THE APU. AFTERWARDS, PILOT SELECTED THE AIR SOURCE TO (NORMAL) THEN SMOKE BEGAN EMITTING FROM THE RT SIDE OF THE COCKPIT BETWEEN THE GLARESHIELD AND WINDOW. PILOT SELECTED THE AIR SOURCE TO (OFF) THEN SHUTDOWN THE APU. FOUND COPILOT`S MFD AS THE SOURCE OF THE SMOKE. REMOVED AND REPLACED COPILOT`S MFD. OPS GOOD. EXTENSIVE GROUND TESTING INCLUDING OPS OR AIR COND SYS WAS CARRIED OUT AND ALL WAS FOUND TO BE NORMAL.