As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMBOUT, AN ACRID ODOR BEGAN ISSUING FROM AIR CONDITIONING DUCTS. THE ENGINE ANTI-ICE WAS ON AND NORMAL PNEUMATIC CONFIGURATION. SELECTED A COLDER TEMP ON PACKS AND FUMES EVENTUALLY DISSIPATED. FOUND INOPERATIVE LIGHTING BALLAST AT ROW 33ABC. BALLAST HAD BURNED ELECTRICAL ODOR. REPLACED BALLAST IAW AMM 33-20. RAN AIR CONDITIONING PACKS. NO ODOR DETECTED. ACFT OK FOR SERVICE.