What was found
PILOTS NOTED SMOKE COMING FROM AIR VENT WHEN ENGAGING L PACK. ATTEMPTED TO RECREATE THE EVENT AND NOTED SMOKE STILL COMING FROM THE AIR VENT HOWEVER THERE WAS STILL NO ACTIVE FAULTS ON THE EICAS OR IN THE MDC. INTERROGATED MDC AND FOUND RECURRING FAULT ACSC 1/INTERNAL FAULT-B1 CODE: 211941. TROUBLESHOT ACCORDING TO CRJ900 FIM 21-61-04-810-816-A01. REMOVED AND REPLACED LH PACK DISCHARGE TEMP. SENSOR IAW CRJ900 AMM21-51-22-000/400-801-A01. LH PACK DISCHARGE TEMP SENOR OPS CHECK GOOD. LH PACK FAULTED AND OBSERVED SMOKE PRESENT IN THE COCKPIT. NEW B1 CODE - 211941, L PACK DISCH. OVERTEMP. PACK STILL ON MEL.