As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ACFT WAS SNAGGED WITH A VACUUM LOW ANNUNCIATOR LIGHT ON IN LOW IDLE AND DURING THE DEICE BOOT MANUAL CYCLE. THE VACUUM RELIEF VALVE WAS FOUND WORN AND REPLACED. SINCE FEBRUARY 2012, WE HAVE REPLACED 9 VACUUM RELIEF VALVES AT OUR BASE.