What was found
CONT CAB ZONE TEMP LIGHT ILLUMINATED ON MASTER CAUTION RECALL. LIGHT EXTINGUISHES W/MASTER RESET. GROUNDED - YES. INITIAL EVAL, CONT CAB ZONE TEMP ON RECALL. PERFORMED PZTC BITE IAW B737-800 FIM 21-62 TASK 801 PZTC 1/2. GOT A FEW VARIOUS INDICATION WHEN BIT CHECKED MULTIPLE TIMES. FIRST #1 PZTC HAD "THIS PACK - TCV", #2 PZTC HAD "FLT DECK TRIM VALVE." PERFORMED CABIN TEMP CONT AND INDICATION OPS TEST IAW B737-800 AMM 21-61-00-700-807-000. NO DEFECTS NOTED. RE-RAN BITE. #1 PZTC HAD "FLT DECK TRIM VALVE." DUE TO HISTORY, REMOVED AND REPLACED CONT CAB TAV IAW AMM 21-61-21-000/400-801. PASSES LEAK CK. PASSES BITE.