What was found
(CAN) DURING CRUISE THE CREW RECEIVED A PRESSURIZATION AUTO FAIL INDICATION. THE QRC REQUIRED THE CREW TO CONTROL THE CABIN IN MANUAL. AFTER SWITCHING TO MANUAL THE CREW WAS UNABLE TO CONTROL THE CABIN PRESS. AN EMER DECENT WAS CARRIED OUT & THE ACFT DIVERTED WERE IT LANDED WITHOUT INCIDENT. FOUND A POTABLE WATER FITTING NEAR THE OUTFLOW VLV HAD FROZEN & BROKE CAUSING WATER TO SPRAY ONTO THE OUTFLOW VLV, THE WATER FROZE ON THE OUTFLOW VLV & PREVENTED NORMAL OPERATION CAUSING CABIN PRESS PROBLEMS.