What was found
PASSENGER REPORTED BURNING ODOR OUT OF REAR OF AIRCRAFT. MAINTENANCE INSPECTED ALL AFT COMPARTMENT WIRING FOUND POWER WIRES FOR CABIN VENT FAN TO BE BEGINNING TO OVERHEAT DUE TO LACK OF INSULATION INTEGRITY. CUT BAD PORTIONS OF SPLICE ON THE POSITIVE AND NEGATIVE LINES. RE-SPLICED PROPERLY AND INSTALLED HEAT RESISTANT INSULATION AT BOTH POINTS. OPERATIONALLY CHECKED VENT FAN GOOD, WITH NO REMAINING BURNING ODOR IAW MM AND WIRING DIAGRAM MAINTENANCE MANUAL 21-20-00.