What was found
WHILE EN ROUTE TO FSD, FLIGHT 140 HAD A SLIGHT ODOR IN THE COCKPIT. ISOLATED TO AROUND FIRST OFFICER'S MAP LIGHT. PULLED MAP LIGHT CIRCUIT BREAKER, ODOR APPEARED TO GO AWAY. DURING DESCENT, AROUND 8000 FT, ODOR RE-APPEARED. NO OTHER INDICATIONS, (I.E. SMOKE, ETC.). VERIFIED MAP LIGHT OKAY FOR SERVICE. ISOLATED SMELL TO FIRST OFFICER'S CLEARVIEW WINDOW ANTI-FOG WINDOW HEAT. WORK IN PROGRESS.