As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFT CAB ZONE TEMP LIGHT ON RECALL PER DESCENT CHECKLIST. LIGHT WENT OUT UPON MASTER CAUTION RESET. GROUNDED - YES. TROUBLE SHOT PER B737-900 FIM 21-62 TASK 844. APPEARS TO HAVE BEEN AN INTERMITTENT FAULT. BITE VERIFICATION TEST OF BOTH TEMP CONTROLLERS GOOD. PACK OPERATION NORMAL. AFT ZONE TEMP LT REMAINS EXTINGUISHED ON RECALL. HAS NO OTHER RECENT HISTORY. CLEARS MEL 21-19F.