Performed annual Furnace tune up. Goodman split system attic. First time this season system has been turned on. 90% furnace making gurgling noise, till drain cup fills up. adjusted time on thermostat. Tested system. Changed both filters. 20-30-1 and 14-14-1. Also cleaned both return air filter grills. Black flex ducts sealed good shape in attic. Hot surface ignitor ok. Cleaned burners and flame sensor. Gas pressure ok. Blower ok, blower single capacitor 20@19.4 ok. Drainages ok at end, cup filled with condensation, and gurgling noise went away. Heated house up well, good temp splits at this time. Attic looks good.