What was found
CABIN AIR TEMPERATURE IS HARD TO CONTROL. AFT CABIN TEMPERATURE DEMANDS SEEM HIGHER THAN NORMAL TO MAINTAIN ADEQUATE WARMTH AND TO MAINTAIN SAME TEMPERATURE AS THE FORWARD CABIN. THE TEMP CONTROL KNOBS SEEM TO BE IN ABNORMALLY SPLIT POSITIONS TO MAINTAIN ADEQUATE WARMTH. ACFT GROUNDED. CABIN TEMP CONTROLLER BITE SHOWS NO FAULTS. FOUND CABIN TEMP SENSOR FILTERS BADLY CLOGGED. CLEANED FILTERS REF MM 21-61-06. CABIN TEMP CONTROL OPS NORMAL.