What was found
ELECTRICAL ODOR AND FUMES COMING FROM CA AIR VENT WHILE ON THE GROUND WITH APU RUNNING. NO SMOKE. CREW REPORTED ELEC SMELL WHILE SITTING AT THE GATE. WHEN TECH BOARDED ACRT ODOR WAS NO LONGER PRESENT. PERFORMED POWER DOWN, REBOOT OF ACFT. INSPECTED BATTERY, E/E BAY, FLT DECK, & FWD GALLEY FOR SIGNS OF ARCING DAMAGE WITH NO FAULTS FOUND. CONFIG ACFT TO SAME CONFIG WHEN ODOR WAS NOTICED WITH NO FAULT FOUND. CYCLED APU, HYDS, PACKS, & COFFEEMAKER WITH NO FAULTS. UNABLE TO DUPLICATE. IAW AMM 05-51-26-800-801-C1.