What was found
DISPLAY COOL CAUTION MESSAGE IN CRUISE. DID NOT CLEAR WITH QRH. FLIGHT # 3638 CLOSED MSG HAD CLEARED. CHECKED FOR OPERATION OF THE FLIGHT FAN AND GROUND FAN. BOTH FANS CHECKED GOOD. CHECKED DISPLAY COOL FILTER FOR EXCESSIVE DUST. FOUND TO RELATIVELY CLEAN. INSPECTED FLOW SENSOR FOR CLEANLINESS IAW AMM. FOUND CLEAN. INSPECTED DISPLAY COOLING PLENUMS FOR LEAKS. FOUND TO BE IN GOOD CONDITION. FOUND FLIGHT FAN TO BE MUCH LOUDER THAN GROUND FAN. OPENED LH KIDNEY PANEL AND INSPECTED DUCTING. FOUND DUCT WAS DAMAGED AND RUBBING AGAINST FAN BLADES. UPON REMOVAL FOUND IT TO BE FOLDED AND BLOCKING AIRFLOW UNDERNEATH THE RUBBER SLEEVE. R&R DISPLAY COOLING FANS INLET DUCT AND THE #1 DISPLAY COOLING FAN DUE TO RUBBING ON BLADES IAW AMM.