As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FWD CABIN TEMP CONTROLLER IN "AUTO" DOES NOT HOLD SELECTED TEMP. SUPPLY DUCT TEMP FLUCTUATES BETWEEN 0-60C RESULTING IN THE CABIN GETTING TOO HOT AND TOO COLD, BACK AND FORTH. GROUNDED - YES. REF B737-800 FIM 21-61 TASK 864. COULD NOT DUPLICATE. CLEANED FWD CABIN FILTER. OPS NORMAL.