As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNABLE TO CONTROL CABIN TEMP SUPPLY DUCT TEMP SUPPLY DUCT TEMP WOULD NOT GO BELOW 8 DEG F. F/A'S REPORT THAT AFT CABIN IS VERY HOT, MID A BIT COOLER. FOUND THAT AN INCREASE IN POWER CAUSES A MOMENTARY COOLING. ONCE NORMAL CRUISE WAS ESTABLISHED TEMP WOUD GO BACK UP AND COULD NOT BE COOLED. SUSPECT A POSSIBLE BLEED AIR LEAK. ACFT WAS DIVERTED TO DEPARTURE AIRPORT.