I may possibly a noisy HVAC system around my house. When my air converts on, it makes a loud banging sound combined with when it cycles off. I guess I should have my HVAC provider come out and examine my metal vents and the ductwork as the sounds like it would be associated with them. It is more on the rattling sound than anything else. I had my HVAC contractor show up to clean my air ducts earlier this coming year and he didn’t say he saw anything wrong. I am afraid there might be a leak in my ductwork somewhere and that is associated with the noise. Whenever a leak in the ducts, it could make my air run longer and that could not just damage my HVAC system, but it could also cost me a ton of money on my utility bills. Actually, I know the last time I had my HVAC system replaced, my HVAC provider said he found a leak in a ductwork. After he installed the new centralized heating and air conditioning system, I noticed an immediate savings on my utility cost each and every month. I am not sure if that was a result of the new HVAC unit, or considering he found and patched the leak inside my ductwork. I guess I need to have him come out again so that he can inspect my HVAC system. It may be something simple like a loosened nut that holds an surrounding vent down. Then again, it could also be something mechanical in my surroundings handler. If it is something mechanical, then I guess it would best to get it fixed before something breaks down in my HVAC system.