As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD - AFTER TAKEOFF SAW AND SMELLED SMOKE AND FUMES IN COCPIT AND CABIN. RETURNED TO ORD AND LANDED WITHOUT INCIDENT. FOUND LEFT HAND PACK TEMPERATURE VALVE STUCK OPEN. REPLACED LEFT TEMPERATURE CONTROL VALVE. SYSTEM GROUND CHECKED NORMAL OPERATION.