What was found
WITH APU RUNNING, CABIN DUCT TEMP CLIMBED UP TO 60 DEGREES C, PUT PACKS IN MANUAL MODE AND CABIN DUCT TEMP DROPPED TO 50 DEGREES C BUT WOULDN'T GO LOWER. REMOVED FROM SERVICE. PERFORMED MULTIPLE APU & ENGINE RUNS WITH INTERMITTENT HOT AIR POOR FLOW & COLD AIR GOOD FLOW. INTERROGATED CDS FOUND F.C 3003 - PACK FCV. C/W Q400 FIM TASK 21-60-00-810-809 STAP 5.A.(1)(C). R&R PACK FLOW CONTROL & SHUT OFF VALVE REF Q400 AMM TASK 21-52-01-000/400-801. INSPECTED HOSES & WIRING DURING R&R, NO FURTHER DEFECTS. LEAK CHECK IS GOOD OPS TEST 2X WITH BOTH APU AND ENG'S IS GOOD. CONSISTENT COLD AIR & GOOD FLOW. CABIN & F.D DUCT TEMPS BELOW 10 DEGREES C. F.C 3003 DID NOT RETURN - NO PRESENT FAULTS. NO FURTHER ACTION REQUIRED. Q400 MCN 6210194-1 ISSUE 1 WAS C/W. RETURNED TO SERVICE.