As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON TAXI OUT, STRONG ELECTRICAL ODOR IN FLIGHT DECK, THEN F/A REPORTS A VERY LOUD WHIPPING & CRACKING NOISE IN THE BACK OF CABIN. RETURNED TO GATE. REPLACED LEFT PACK GROUND COOLING FAN. RAN BOTH PACKS & BOTH ENGINES. ALL CHECKS NORMAL.