Combines air screen

Not sure what you mean but I think you are talking about the large screen that turns on front of the radiator and if it stops, slows or clogs up with trash you will get the buzzer going off. I have had this happen when going in a certain direction with a strong wind or also one time I forgot to replace the stopper inside the housing after washing out the radiator and it was sucking air through the drain hole and not all coming through the screen also could be bearings.

Some of 1660's and 80's the rotary screen would actually stop turning and just sit there and vibrate. The plate that holds the screen was updated to a heavier one that didn't allow the screen to do this. Check with your nearest dealer whether yours needs this update.