As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CONT CAB ZONE TEMP LIGHT ILLUMINATED WITH MASTER CAUTION. ZONE TEMP LIGHT DID NOT ILLUMINATE ON MASTER RECALL DURING TOP ON DESCENT CHECKLIST. GROUNDED - YES. ACCOMPLISHED B737-900 FIM 21-62 TASK 842. OPERATED LEFT AIR CONDITIONING PACK FOR FIVE MINUTES REFERENCE B737-900 AMM 21-00-00. CONTROL CABIN ZONE TEMP LIGHT STAYS EXTINGUISHED. PERFORMED PACK TEMP CONTROL BITE REF FIM 21-62 TASK 801. NO EXISTING FAULTS LOGGED.