As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT, CABIN PRESS WENT TO 2000 FT/MIN. RATE OF CLIMB UP TO 9500 CABIN ALT WITH NO CONTROL EITHER MANUALLY OR AUTOMATICALLY. RECOVERED AT FL 19000. COULD NOT DUPLICATE. CREW VERBAL, HEAVY RAINS LEAVING ILN. SUSPECT ICE BUILD-UP. INSPECTED OUTFLOW VALVE SUGAR SCOOP AND ASSOCIATED LINKAGE. CLEANED AND RESEATED CANNON PLUG CONNECTOR AT VALVE ACTUATOR. NO DISCREPANCY NOTED. TESTED OUTFLOW VALVE, GOOD REF DC-8 AMM 21-31-04-5-0001.