What was found
DURING CRUISE FLIGHT AT FL350 WITH ANTI-ICE ACTIVATED THE CABIN ALTITUDE STARTED CLIMBING. COM PROCEDURE COMPLIANCE COULD NOT CORRECT THE CABIN RATE OF CLIMB. THE RED -CABIN PRESS- WARNING LIGHT ALONG WITH THE -MASTER CAUTION- LIGHT ILLUMINATED SO A RAPID DESCENT WAS INITIATED. CREW WAS NOT ABLE TO REGAIN CONTROL OF THE CABIN UNTIL 12,000 MSL AND ABOUT THAT TIME THE -FWD ACCESSORY COMP DOOR- WARNING LIGHT ILLUMINATED. FLIGHT DIVERTED TO JAN AND LANDED UNEVENTFULLY. MAINTENANCE FOUND A RUBBER BOOT BLOWN OFF AFT OF THE LEFT WATER SEPARATOR AND MEL'D THE LEFT PACK SYSTEM.