As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE CRUISING AT FL250 SMOKE WAS SMELLED IN COCKPIT THE FOLLOWED BY SMOKE ENTERING THE COCKPIT VIA OVERHEAD VENTS. PERFORMED RUNS AND PACK SYSTEMS TROUBLESHOOTING AND FOUND THAT NR 1 PACK SYSTEM ACM IS CEASED UP. DEFERRED NR 1 AC PACK SYSTEM REF 21-30 AUTH 120090D-C. REMOVED AND REPLACED L/H ACM, IAW EMB AMM 21-51-03.