There’s nothing worse than when you hear a noise that your ears don’t like, lately I have been coming house & hearing a entirely unusual noise. It is usually right after I turn on my Heating & A/C unit in the house. I have tried to follow the noise & figure it out. I have been unable to figure it out on my own. So I had to call my local Heating & A/C contractor because I thought it was coming from the Heating & A/C system. That would explain why it would start as soon as I turned on the Heating & A/C unit. When the Heating & A/C professional came to my house he checked all of the parts within the Heating & A/C system installed. He noticed that there was nothing wrong with the unit itself. The real noise was coming from behind my walls. This meant that the noise was coming from the air ducts laying behind my walls. The air ducts are what helps to transport the air from the Heating & A/C unit to my house. It seemed as if there was a collapse air duct behind my wall. It must have been rubbing up against the wall or the other air ducts inside near it. So the Heating & A/C professional would have to put a big hole in the wall to repair the collapsed air duct. I allowed him to do this however I was also going to need somebody to patch the hole & repaint my wall. It was a big pain in my eyes. So if you can avoid having air docks installed into your house I would, however you would never want this to happen to you because it cost a lot of money & time.