As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FA REPORTS IN FLIGHT AFT CABIN IS VERY COLD EVEN WITH THE AFT CABIN CONTROL TURNED TO WARM AND INDICATES WARM AIR IN THE DUCT. ON THE GROUND APU RUNNING AND AFT CABIN CONTROLLER ON FULL WARM FA STILL REPORTS THE AIR IS LUKE WARM AT BEST. GROUNDED - YES. TEMP CONTROL BITE - NO FAULTS. RAN PACK AND OPERATED TEMP SELECTORS, SYSTEM OPS AS EXPECTED. NO HISTORY 90 DAYS.