What was found
CONTROL CABIN ZONE TEMP LIGHT ILLUMINATES ON RECALL AND RESETS WITH MASTER CAUTION RESET. GROUNDED - YES. SYSTEM HAD CONTROL CABIN TRIM MODULATING VALVE FAULT. IT RESET & SYS BITE PASSED BUT THERE IS A PREVIOUS WRITE UP LAST WEEK. SAME FAULT & RESET WITH NO LRU CHANGE. CONT CAB ZONE TEMP LT DOES NOT SHOW ON MASTER RECALL. PERFORMED PZTC BITE IAW FIM 21-62 TASK 801, NO FAULTS PRESENT ON EITHER CONTLR 1 OR 2, BIT, PREV, OR VERIFY, GREEN ON VERIFY, RESET X2. AS PRECAUTION, CLEANED FLT DECK TEMP SENSOR IAW AMM 21-61-10-100-801. FILTER WAS EXTRA DUSTY. PERFORMED CABIN CONT AND INDICATION OPS TEST IAW AMM 21-61-00-700-807-002. BOTH PACKS RAN INDEPENDENTLY AND TOGETHER, HIGH AND LO, NO OBSERVED DEFECTS.