What was found
TEMP CONTROL OF MAIN CABIN VERY ERRATIC. LARGE TEMP SWINGS + 15 DEGREES WITH SLIGHTEST MOVEMENT OF CONTROL KNOBS (SUPPLY DUCT READING). WITH POSITIONED TRIM AIR SWITCH TO OFF ABLE TO KEEP TEMP SWINGS REASONABLE BOTH MAIN CABIN KNOBS POSITIONED IN THE TWO O'CLOCK AREA. GROUNDED YES. PERFORMED FIM 21-61 TASK 863 AND FIM 21-61 TASK 864. AUTO TEMP CONTROL FOR BOTH CABIN TEMPS OPS NORMAL. VERIFIED OPS NORMAL SAME. FOUND BOTH CABIN SENSOR FILTERS DIRTY CLEANED PER SAME.