What was found
ON TAXI OUT CONT CABIN ZONE TEMP LIGHT ILLUMINATED. EXTINGUISHED WITH MASTER CAUTION RESET. GROUNDED - YES. PERFORMED PACK ZONE TEMPERATURE CONTROLLER BITE TEST PER B737-900 AMM 21-61-00-700-806-002. RH PZTC FAULTED IN PREVIOUS FLIGHT 4 LEGS AGO CONT CABIN TRIM VALVE CURRENT 3 LEGS ON FAULT AND FAULT RESET, OPERATED A/C PRESS FOR 5 MINUTES PER AMM 21-60-00-700-807-002 AFTER REACCOMPLISHED PZTC BITE AND NO FAULTS NOTED.