I knew I was having a problem with our furnace, however whenever the Heating as well as A/C supplier showed up to check it out, there was nothing wrong. I thought there was something wrong with me, plus maybe I had a disease where I was regularly imagining something wrong with our furnace. The next time I heard the odd grinding noise, I decided to tape it with our cellphone. By the time I had our cellphone out plus ready to record, the noise quit again. I didn’t know what was going on, however I knew that if I let it go on, I could end up needing a new furnace. I waited for several weeks before calling the Heating as well as A/C supplier again. The Heating as well as A/C tech came to the home plus did a full inspection of the furnace. She told me she couldn’t find a single thing wrong. I was wondering if it was possible for a furnace to fix itself, when the noise happened again, plus the Heating as well as A/C tech heard it. She looked at me plus asked if that is what I had been hearing? I nodded, plus she sat there quietly plus listened again. The two of us went downstairs, plus she pointed to the air duct. There was a small hole in the air duct. When the furnace turned on, there was just enough air blowing through to cause a whistle. I was never so glad to find something wrong with the air duct as I was that day. If the Heating as well as A/C tech hadn’t been there, the people I was with and I would have never found the problem. The air duct was cleaned plus repaired several nights later.