What was found
REJECTED TAKEOFF, UNUSUAL BLEED AIR NOISE IN COCKPIT WHEN THROTTLES WERE ADVANCED FOR TAKE-OFF. TAKE-OFF ABORTED BEFORE 60 KNOTS, DISCOVERED COCKPIT WINDOW DEMISTER CONTROL VALVE IN FULL OPEN POSITION, REPOSITIONED CONTROL HANDLE TO NORMAL POSITION. SUBSEQUENT TAKEOFF, NO FURTHER PROBLEM. (NO DEFECT, VALVE IN WRONG POSITION FOR TAKE-OFF. PRECAUTIONARY REJECTED TAKEOFF BECAUSE OF UNUSUAL BLEED AIR NOISE)