MECHANICALLY CLEANED INDOOR AND OUTDOOR UNIT .FLUSHED DRAIN LINE AND PAN. ADDED DRAIN TREATMENT AND DAWN. VERIFIED ALL AMP DRAWS AND ELECTRICAL CONNECTIONS. CHECKED ALL REFRIGERANT LEVELS AND TEMPERATURES. SYSTEM IS OPERATING NORMALLY AT THIS TIME. CUSTOMER ADVISED ME THEY HEARD A SQUEAKING NOISE FROM KITCHEN AREA. COULD NOT GET UNIT TO DUPLICATE THIS NOISE. WHIKE IN ATTIC I DID NOTICE A ROTARY ROOF VENT. VENT WAS TURNING WHILE THERE. NOISE COULD POSSIBLY BE WHEN ATTIC IS VERY HOT OR WIND IS CAUSING VENT TO SPIN FASTER CAUSING NOISE. INFORMED CUSTOMER IF NOISE HAPPENS AGAIN TO TURN OFF SYSTEM AND SEE IF NOISE HAPPENS WHEN UNIT OFF.