What was found
D: RECIRC FAN FAULT STATUS MESSAGE APPEARED IN FLIGHT. FOUND CIRCUIT BREAKER 1-A5 OPENED. WE SMELLED A SLIGHT SMELL OF ELECTRICAL BURN AND TURNED RECIRC FAN OFF. MESSAGE CLEARED AND SMELL WENT AWAY. / C: MEL 21-22-1B / CAT C EXP 12-9-21 / MTC ACTION COMPLIED WITH / RECIRC FAN FAULT STATUS MESSAGE APPEARED IN FLIGHT. FOUND CIRCUIT BREAKER 1-A5 OPENED. WE SMELLED A SLIGHT SMELL OF ELECTRICAL BURN AND TURNED RECIRC FAN OFF. MESSAGE CLEARED AND SMELL WENT AWAY. (FLIGHT 3517 - FILED CLOSED) NOV 29, 2021 STATION: DTW--DEFERRED BOTH RECIRC FANS PER MEL 21-22-1B. MX PROCEDURE COMPLIED. BOTH RECIRC FANS INOP. PLACARDS INSTALLED.