What was found
SMOKE ON FLIGHT DECK AT GATE. SMOKE APPEARED THROUGH SIDE WINDOW DEMIST VENTS. APU WAS RUNNING AND DEICING WAS BE CONDUCTED. REMOVED FROM SERVICE. C/W FORM M-744 ODORS/SMELL CHECKLIST, REMOVED ODOR FROM CABIN AND DUCTS REF. TASKS 05-50-04-160-802, 21-00-00-160-801. ENGINES WERE NOT RUNNING. APU DID NOT AUTO SHUT DOWN. C/W GVI OF APU NO DEFECTS NOTED. NO SMOKE OR ODORS DURING OPS TEST OF THE APU AIR. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.