As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BURNING-ACRID ODOR IN COCKPIT, RTFL BURNING ACRID ODOR IN COCKPIT. TURNED UPPER FANS OFF WITH NO CHARGE OF ODOR, TURNED OFF UPPER FANS AND SMELL STARTED TO DISSIPATE. NO MSG'S PRESENT. MAINT PG SHOWED NORMAL INDICATIONS. DEFERRED BOTH LOWER RECIRCULATIONS FANS IAW MEL 2125. REPLACED BOTH LWR RECIRC FANS & FILTERS PER MM CHECKS OK. REPLACED BOTH LOWER RECIRC FANS AND FILTERS PER MM, CHECKS OKAY.