What was found
L PACK TEMP. CLEARED AFTER QRH, LEFT IN N POSITION PER PROCEDURE. PERFORMED PACK TEMPATURE CONTROLLER BITE TEST IAW AMM 21-51-14. BITE TEST GOOD. PERFORMED OPS CHECK OF COOLING PACK IAW AMM 21-51-00, OPS CHECK GOOD NO DEFECTS NOTED AT THIS TIME. DUE TO HISTORY TRANSFER TO MDDR 143784 IAW MEL 21-51-03-01 CATC. REMOVED AND REPLACED LT PACK FLOW CONTROL AND S/O VALVE IAW AMM 21-51-01. DURING OPS CHECK FOUND TRIM AIR CHECK VALVE STUCK OPEN. INSPECTED AND CLEANED CHECK VALVE. OPS CHECK NORMAL IAW AMM 21-61-05. LT PACK OPS CHECK NORMAL IAW AMM 21-51-00.