What was found
EN ROUTE AT CRUISE WHEN COCKPIT A/C WAS SELECTED WARMER A STRONG SMELL OF WHAT APPEARED TO BE FUEL WAS OBSERVED THROUGH THE COCKPIT ECS SYSTEM WHEN TEMP CONTROLLER WAS MOVED BACK TO COLD THE ODOR WENT AWAY AND WAS NOT OBSERVED ANYMORE. REMOVED AND REPLACED FUEL VALVE SOLENOID ON APU. RAN PACKS FROM ENGINE AND APU. FUEL SMELL NOT PRESENT, WATER SEPARATOR IS CLEANED. (M)