What was found
CONT CAB ZONE TEMP LIGHT COMES ON WITH RECALL, IT GOES OUT WHEN MASTER CAUTION IS RESET. GROUNDED - YES. PERFORMED PACK ZONE TEMPERATURE CONTROLLER BITE TEST PER AMM 21-51-00-700-803. #2 CONTROLLER FAULT FLT DECK TRIM VALVE. ACFT RELEASED ON MEL 21-21G. UNABLE TO DUPLICATE DEFECT OR PREVIOUS FINDING. PACK/ZONE TEMP CONTROLLER BITE PER B737-800 FIM 21-62 TASK 801 SHOWED NO FAULTS AND VERIFY TEST PASSED WITH NO FAULTS. DUE TO PREVIOUS FINDING, ACCOMPLISHED INITIAL EVALUATION FOR FLIGHT DECK TRIM VALVE FAULT PER FIM 21-62 TASK 832 - VERIFY TEST AGAIN PASSED WITH NO FAULTS. FOUND CONTROL CABIN TEMP SENSOR FILTER CLOGGED WITH DUST. REMOVED AND REPLACED FILTER PER B737-800 AMM 21-61-06-000-801/AMM 21-61-06-400-801 AND PERFORMED CABIN TEMPERATURE CONTROL AND INDICATION OPERATIONAL TEST PER AMM 21-61-00-700-807-002 - ALL TESTS PASS.