What was found
FLIGHT 3972, THE CREW REPORTED THAT DURING CLIMB AND CRUISE, STRONG ELECTRICAL/PHOSPHORUS ODOR THROUGH OUT THE AIRCRAFT. THE ODOR DIMINISHED AFTER TURNING THE RECIRCULATION FAN OFF. AIRCRAFT LANDED WITHOUT INCIDENT & REMOVED FROM SERVICE. COMPLIED WITH FAULT ISOLATION MANUAL TASK 21-20-00-810-801-A, AIR CONDITIONING-DISTRIBUTION-SMOKE/ABNORMAL ODOR IN THE CABIN/COCKPIT-UNKNOWN SOURCE FOUND AFT GASPER FAN PRODUCING ODOR. REMOVED AND REPLACED IAW 21-23-03. OPS CHECKED GOOD, NO DEFECT NOTED. AIRCRAFT RETURNED TO SERVICE.