What was found
(CAN) FLIGHT CREW REPORTED OF THE EVENT, FLIGHT COMPARTMENT DUCT HOT & CABIN HOT CAUTION LIGHT ILLUMINATED DURING CLIMBOUT. FLIGHT COMPARTMENT DUCT TEMP OBSERVED TO BE IN YELLOW BAND ON DUCT TEMP GAUGE. QRH FOR FLT COMPARTMENT DUCT HOT AND CABIN HOT C/O. PHASE OF FLIGHT IN WHICH THE EVENT TOOK PLACE, CLIMB. AIRCRAFT HOURS AND CYCLES OF THE EVENT, 15625:05/15098. COCKPIT DISPLAYED INFORMATION DURING THE EVENT, FLIGHT COMPARTMENT DUCT HOT & CABIN HOT CAUTION LIGHT ILLUMINATED ECS PACK BY-PASS VALVE AND ECS CONTROL PANEL. REMOVED AND REPLACED. AIRCRAFT RETURN TO SERVICE. (TC NR 20180207027).