What was found
UNABLE TO CONTROL TEMP IN FWD CABIN WITH FWD CABIN TEMP CONTROL IN AUTO. AT 12 O`CLOCK POSITION SUPPLY DUCT IS BETWEEN 0 DEGREES AND 2 DEGREES C AT 2 O`CLOCK POSITION SUPPLY DUCT IS BETWEEN 60-70 DEGREES C. IN OFF TEMP IS STEADY AT 20 DEGREES C. ACFT GROUNDED. CABIN ZONE TEMP SENSOR FILTERS VERY DIRTY. CLEANED BOTH FWD AND AFT CABIN FILTERS IAW MM 21-61-06. NO FAULTS EITHER ZONE TEMP CONTROLLER IAW FIM 21-61, TASK 801.