As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED COLD CABIN AT ALTITUDE. AFTER SOME TROUBLESHOOTING, INSPECTION OF THE CABIN DUCTING AND ENGINE GROUND RUNS WITH NO OBVIOUS FAULTS WE FOUND THIS DUCT TO BE TORN WHERE IT PASSES THROUGH THE RH PYLON STRUCTURE. THE DEFECT WAS NOTED WHILE CHECKING THE DUCT FOR SECURITY AT HE PASS THROUGH BY FEELING AROUND THE DUCT. THE TORN AREA WAS ON THE AFT SIDE OF THE DUCT AND NOT VISIBLE DUE TO THE INSULATION WRAP STILL BEING INTACT. DUCT WAS REPLACED WITH A NEW PART.