What was found
OPE ECS/PRESSURIZATION FAIL ON CLIMB AT APPROXIMTELY 13000 FT, ALSO FAILED HOLDING CABIN PRESSURE ON MANUAL MODE. OPEN ACCESS PANEL BELOW COPILOT SEAT. FOUND A AN FITTING SLIGHTLY LOOSE ON CHECK VALVE NEXT TO EJECTOR, JET. REMOVED CHECK VALVE BY REMOVEING THE AN FITTINGS ON EACH SIDE. INSPECTED & CHECKED FLOW OF AIR. REINSTALLED THE CHECK VALVE. PERFORMED OPERATIONL TEST OF PRESSURIZATION CONTROL SYSTEM IN REFERENCE TO PC-12 AMM 12-A-71-00-00-00A-903A-A. OPS CHECKED NORMAL. FLIGHT CHECK FOUND NO DEFECTS.