As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. DURING CRUISE AT FL330 JUST PRIOR TO DESCENT WE HAD A BURNING ACRID SMELL IN THE FLIGHT DECK . IT WAS VERY LIGHT AND ONLY LASTED A VERY SHORT PERIOD. PERFORMED J/C 26L00021001 SMOKE ODOR FUMES INITIAL TROUBLESHOOTING. AVIONICS BLOWER FAN WAS SOURCE OF FUMES. REPLACED AVIONICS BLOWER FAN PER AMM 21-26-51.