As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
COCKPIT WAS VERY COLD, TURN TEMP CONTROL TO FULL WARM DUCT TEMP NEVER GOT OVER 30 TRIED IN OFF POSITON , NO CHANGE IN FULL WARM, ALL VENTS BLOWING COLD AIR. ACFT GROUNDED. DURING BITE TEST FOUND NR 1 TRIM AIR MODULATION VALVE INOPERATIVE. R & R TRIM AIR MODULATION VALVE IAW AMM. 21-61-21. VALVE OPS AND LEAKS CHECKED GOOD.