As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AS THE AIRCRAFT WAS CLIMBING THROUGH FL240, AN ELECTRICAL BURNING SMELL WAS REPORTED IN THE CABIN. CREW NOTED THAT THE OVERHEAD CIRCUIT BREAKER FOR THE LEFT AIR CONDITIONING REGULATOR VALVE (B-13) HAD TRIPPED. MAINTENANCE REPLACED THE PRESSURE REGULATOR VALVE AND ACCOMPLISHED OPN 5089, PNEUMATIC SYSTEM DUCT BURNOUT. (2011-D1373)