As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE COMING FROM AIR CONDITIONING SYSTEM WITH PACKS ON. PERFORMED PRESSURE CHECK OF BOTH PACKS WITH APU/ENG 1/ENG 2 IAW CRJ200 AMM 21-50-00 NO SMOKE NOTED. FOUND DUCT TO BE DISCONNECTED AT HEAT EXCHANGER. INSTALLED NEW COUPLING AND RE-INSTALLED DUCT ON EXCHANGER. OPS CHECK GOOD.