As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT CRUISE CABIN TEMP UNCOMFORTABLY HOT UNLESS AUTO FORWARD AND AFT TEMP CONTROLLED FULL COLD. CABIN AIR TEMP INDICATOR INDICATES 18 DEGREES C THROUGHOUT CABIN. ALL AFTER 3 HOURS AT CRUISE ALTITUDE. GROUNDED, YES. INSPECTED CABIN FILTER SCREEN AND REMOVED DEBRIS. VERIFIED NORMAL SYSTEM OPS, REFERENCE FIM 21-61 TASK 863/864.