What was found
STRONG BURNING ELECTRICAL ODOR IN THE FLIGHT DECK OCCURRED DURING SHUTDOWN CHECKLIST. DISSIPATED AFTER TURNING THE LEFT PACK OFF. TURNED LEFT PACK BACK ON AND ODOR DID NOT REOCURE. ISOLATION VALVE WAS RETURNED TO NORMAL WHEN GOT THE SMELL. ACFT GROUNDED. RAN THE LT PACK ON HIGH, NO SMOKE OR ELECTRICAL ODORS DETECTED. INSPECTED AND FOUND CABIN FAN FILTERS CAKED WITH LINT. CLEANED ALL THREE FILTERS AS REQUIRED. REINSTALLED. SYS CHECKED NORMAL.