As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON TAXI OUT, CONT CAB ZONE TEMP LIGHT ILLUMINATED. ACCOMPLISHED QRH & LIGHT EXTINGUISHED. W/ MASTER CAUTION RESET. GROUNDED - YES. REPLACED ZONE TRIM MODULATING VALVE REF B737-900 AMM 21-61-21. PERFORMED PACK/ZONE TEMPERATURE CONTROLLER BITE TEST AND FAULT CLEARED.