What was found
ON MASTER CAUTION RECALL CONT CAB ZONE TEMP LIGHT ILLUMINATED. RAN QRH PROCEDURE LIGHT WENT AWAY ON MASTER CAUTION RESET. GROUNDED - YES. INITIAL EVALUATION, CONT CAB ZONE TEMP LT PRESENT ON MASTER RECALL AT OVERHEAD. PERFORMED PZTC BITE IAW B737-900 FIM 21-62 TASK 801. HAD FLT DECK TRIM VALVE RED LT ON BIT ON #2 RH PZTC, CLEARED ON VERIFY. LH= NO FAULTS. CONT CAB ZONE TEMP LT CLEARED FROM MASTER RECALL. AS PRECAUTIONARY, CLEANED FLT DECK TEMP SENSOR TEMP BULB IAW B737-900 AMM 21-61-10-100-801, REPLACED FILTER. PERFORMED CABIN TEMP INDICATION AND OPS TEST IAW AMM 21-61-00-700-807-002, NO DEFECTS NOTED. RE RAN PZTC BITE, NO FAULTS ON 1/2.