As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX-FLIGHT ATTENDANT REPORTED ODORLESS HAZE IN CABIN AFTER START. HAZE WENT AWAY IN ONE MINUTE. UNPLUGGED DUCT DRAIN LINE FROM AIR CYCLE MACHINE. REINSTALLED DRAIN LINE. GROUND RAN AIRCRAFT. OPERATIONAL CHECK GOOD. NO HAZE OR MIST SEEN IN CABIN. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.