What was found
COCKPIT ODOR: WHILE PROGRAMMING THE AIRCRAFT FOR OUR NEXT FLIGHT, WE NOTICED A DISTINCT ODOR IN THE COCKPIT; POSSIBLY ELECTRICAL IN NATURE. WE NOTICED A SLIGHT HAZE IN THE COCKPIT. WE POWERED DOWN THE AIRCRAFT UPON DISCOVERY. APU POWER, BLEED AIR, AND INTERIOR HAVE ALL BEEN POWERED ON FOR 30 MINUTES PLUS, IN ADDITION TO PREVIOUS FLIGHT. THE ODOR PURSISTED SEVERAL MINUTES AFTER THE SECURING CHECKLIST. PERFORMED OPS CHECKS. NO DEFECTS NOTED. UNABLE TO DUPLICATE. REPLACED HEPA FILTER. REF AMM 49-10-15, 49-10-00 AND 21-70-10.