Tin foil was the culprit
A few years back I was living in this 1 apartment I was renting. And every time that the central heating plus cooling system device would come on I would hear this crumpling of paper category sound that was almost like a rattling sound. It was driving myself and others nuts forever! I could not figure out why every single time the central heating plus cooling system device would come on that this noise would be going on! Well, 1 afternoon I finally had enough of it plus I wanted to investigate into this. The noise was only coming from the air vents in the dining room. In the study room plus other parts of the apartment it was not happening. So I decided to get a ladder plus go up to have a look at the air vents of the central heating plus cooling system device in the dining room. The air vents were in vaulted ceilings so I needed the ladder. When I had a deep look into the air vents I found what was going on! There was tin foil in there for some reason. Before I unlinkd this tin foil from the air vents of the central heating plus cooling system device I wanted to check with our proprietor first to make sure it wasn’t there for a reason! My proprietor did not suppose why it was there plus was surprised himself! So I went back up there, took off the air vent cover plus got the tin foil unlinkd from the air vents of the central heating plus cooling system device in the dining room section of the house.