What was found
PDIS 607 30-20 1349 07JAN23 OAK OPEN U ENG 1 ANTI ICE DISAG. DUE TO FREEZING FOG AND ICING IN ANCHORAGE, WE RETURNED TO OAKLAND MEL 07JAN23 12:49 OAK U RELEASED FOR SERVICE PER MEL 30-22-01-02-A. NR 1 ENG ANTI-ICEVALVE - INOP OPEN. USE PERFORMANCE PENALTIES." VALVE LOCKED OPEN. TROUBLESHOOTING AND IPC EFFECTIVITY/APPLICABILITY VERIFICATION IS REQUIRED PRIOR TO INSTALLING PART (S). AMM: 30-22-01-4-1. REMOVED AND REPLACED #1 ENGINE ANTI-ICE VALVE IAW AMM 30-22-01-4-1. FUNCTIONAL TEST IS GOOD PER AMM 30-22-00-5-1, CLEARED MEL.