As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ZONE TEMP LIGHT ILLUMINATES ON MASTER PANEL. GROUNDED-YES. PERFORMED B737-900 FIM TASK 21-62 TASK 832. BITE ON RT PACK/ZONE TEMP CONTROLLER FOUND FAULT "FLT DECK TRIM VALVE", FURTHER T/S FOUND 120 VAC AT CONNECTOR D3886 AS PER STEP F(3)A REQUIRES REPLACEMENT OF THE CONTROL CABIN TAV V143. REMOVED AND REPLACED CONTROL CABIN TRIM AIR MODULATING VALVE, REF B737-900 AMM 21-61-21/401. BITE AND LEAK CHECK GOOD.