- Jul 8, 2012
2 blocks is kinda far fetched but I have to say, I once experienced crippling headaches because of low frequency vibrations caused by the AC unit in an old house of mine. They were so low that we couldn't hear them yet I would get a headache several hours after it was turned on every time. It was not a freon leak either. The problem was fixed when we had the main fan replaced, apparently there was a slight wobble in the blades that caused resonance in the unit.