What was found
THE CABIN HEATER WAS ON AND AS USUAL SMALL AMOUNT OF SMOKE & ENGINE CLEANER ODOR IS PRESENT WHEN HEATER IS INITIALLY TURNED ON. CREW INFORMED PASSENGERS THAT THIS WAS NORMAL. DURING TAKEOFF THE AFT BAGGAGE COMPARTMENT LIGHT ILLUMINATED. TAKEOFF WAS ABORTED , RETURNED TO BASE & LANDED. HEATER WAS TURNED OFF.VISUALLY INSPECTED BAGGAGE COMPARTMENT FOUND NO EVIDENCE OF SMOKE OR FIRE. MAINTENANCE LATER FOUND CRACK IN BAGGAGE COMP. HEATER DUCT WHICH WAS REPAIRED.