What was found
APU FIRE WARNING LIGHT IN HANDLE AND FIRE WARNING ON GLARESHIELD CAME ON. PULLED FIRE HANDLE, LIGHT STAYED ON. DISCHARGED APU BOTTLE, LIGHT STAYED ON. LIGHT EXTINGUISHED ON DESCENT INTO IAH 10 MIN LATER. LIGHT CONTINUED TO FLICKER IN HANDLE INTERMITTENT IN DESCENT & ON GROUND. CHECKED APU FIRE SENSOR LOOP AND SHOOK DOWN CONNECTORS ON APU. NO FAULTS NOTED. CLEANED C/P D4858P AND R421 PER WDM. REMOVED AND REPLACED APU FIRE DET OPERATION UNIT PER MM 26-15-003-4. REMOVED AND REPLACED FIRE BOTTLE PER MM 26-23-001-4.