What was found
GOT A "CONT CAB" ZONE TEMP LIGHT APPLIED QRH - COOLED THE FLIGHT DECK AND LIGHT EXTINGUISHED. SAME SITUATION OCCURRED A SECOND TIME. GROUNDED - YES. PERFORMED INITIAL EVALUATION FOR FLT DECK ZONE TRIM VALVE FAULT PER B737-800 FIM 21-62 TASK 832 AND TASK 833 - "VERIFY" TEST PASSED ON BOTH CONTROLLERS WITH NO FAULTS. REMOVED AND REPLACED CONTROL CABIN TEMP SENSOR FILTER PER B737-800 AMM 21-61-06-000-801/AMM 21-61-06-400-801. PERFORMED CABIN TEMPERATURE CONTROL AND INDICATION - OPERATIONAL TEST PER AMM 21-61-00-700-807-002 - ALL TESTS PASS.