As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON DESCENT THROUGH 20000FT LEFT PACK LIGHT ILLUMINATED, FOLLOWED QRH- LIGHT EXTINGUISHED WITH MASTER CAUTION RESET. GROUNDED - YES. PERFORMED BITE CHECK OF PACK/ZONE TEMP CTRL. NR 1 PZTC LOGGED "RAM AIR ACT" LAST FLIGHT, REF AMM 21-51-00, FAULT RESET.