What was found
SEA - NR 1 BLEED HOT CAUTION LIGHT ILLUMINATED AT APPROXIMATELY 13,000 FEET TURNED OFF BLEED NR 1 IAW CHECKLIST AND LIGHT EXTINGUISHED. RESET BLEED NR 1 IAW CHECKLIST, AND BLEED HOT CAUTION ILLUMINATED AGAIN. TURNED NR 1 BLEED OFF AGAIN AND NR 1 BLEED HOT CAUTION CAME ON AGAIN AND REMAINED ON FOR ALMOST 2 MINUTES BEFORE EXTINGUISHING, 3 MINUTES LATER, THE NR 1 BLEED HOT ILLUMINATED ON APPROACH FOR 40 SECONDS AND THEN EXTINGUISHED. FOUND "LT BLD ANA OT" FAULT MESSAGE IN CDS. REMOVED AND REPLACED NR 1 BLEED AIR OVERTEMP SWITCH IAW AMM TASK NR'S 36-11-16-000-801, AND 36-11-16-400-801. RAN ENGINES BLD HOT CAUTION DID NOT RE-OCCUR. NO FURTHER DEFECTS. RETURNED TO SERVICE.