What was found
FIRST OFFICER`S MCDU BLANKED OUT AT LEAST FOUR TIMES OVER A PERIOD OF LESS THAN ONE HOUR. DISPLAYED FAIL LIGHT. SEEMED TO RUN A BIT TEST AND RECOVER TEMPORARILY. NO OTHER CHANGES NOTED. OPERATED NORMALLY AFTERWARD. ACFT GROUNDED. FAULT CODE 346-040-32 INITIAL INSPECTION, RT MCDU WORKING, LCD TEMP WAS READING 36 DEGREES C. REMOVED CDU AND FOUND DUST BLOCKAGE IN COOLING VENTS. CLEANED COOLING VENTS IAW AMM 34-61-01-100-801, VERIFIED EQUIPMENT COOLING WORKING PROPERLY TO MCDU RACK. REINSTALLED AND RAN FOR 30 MINUTES, NO DEFECTS NOTED. LCD TEMP DROPPED TO 28 DEGREES C. NO HISTORY LAST 30 DAYS.