What was found
IN MASTER CAUTION RECALL AFTER ENGINE START ZONE TEMP CONT CAB ILLUMINATED ACCOMPLISHED QRH LIGHT EXTINGUISHED UPON MASTER CAUTION CANCEL. GROUNDED - YES. PACK/ZONE TEMP CONTROLLER BITE PER B737-900 FIM 21-62 TASK 801 SHOWED FAULT FOR CONTROL CABIN TRIM VALVE. ACCOMPLISHED T/S FOR CONTROL CABIN TRIM VALVE FAULT PER FIM 21-62 TASK 832 - PZTC VERIFY TEST DID NOT CONFIRM FAULT. CLEANED CONTROL CABIN TEMP SENSOR AND REPLACED FILTER PER B737-900 AMM 21-61-06. PERFORMED CABIN TEMPERATURE CONTROL AND INDICATION OPERATIONAL TEST PER AMM 21-61-00-700-807-002 - ALL TESTS PASS.