As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT FL 400 CREW REPORTED SMOKE AND FUMES IN THE COCKPIT APPROX 3 MINS AFTER ACTIVATING/OPENING FLIGHT DECK HEAT VALVE. SMOKE WENT AWAY AFTER HEAT VALVE WAS CLOSED. MAINTENANCE COULD NOT DUPLICATE THE DISCREPANCY. DUCTS WERE CHECKED FOR EVIDENCE OF CONTAMINATION BUT NONE WAS FOUND. MAINTENANCE PERFORMED HIGH POWER ENGINE RUNS AND A CHECK FLIGHT WITH NO FURTHER DISCREPANCIES.