As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EXTREMELY HOT AIR AT ROW 30. EVERYWHERE ELSE IN CABIN IS COOL. FLOW STOPPED WHEN AFT CARGO HEAT TURNED OFF, INOPED AFT CARGO HEAT SYS. REACTIVATED CARGO HEAT SYS VLV NOT THE PROBLEM. FOUND CRACKED DISTRIBUTION DUCT. REPLACED PNEUMATIC DUCT IN AFT PIT LT SIDE. LEAKED CHECKED SATISFACTORILY.