As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED, AIR INTERRUPT. EMERGENCY DECLARED. LANDING UNEVENTFUL. ACFT NOT OVERWEIGHT. AFTER TURNING OFF ANTI-ICE THE PRESSURIZATION FLOW LIGHT ILLUMINATED. IN MANUAL MODE, CABIN ALTITUDE CONTINUED TO INCREASE. CABIN PRESSURIZATION BECAME UNCONTROLLABLE. MAINTENANCE FOUND LT WATER SEPARATOR FREEZING UP AND LEAKING. R & R WATER SEPARATOR IAW AMM 21-20-02.