[lbrachfe]

Does anyone possess the wisdom to explain to me any way to make the units quieter ? my fans are noisier than they used to be with a vibrate/rumble but not loud just annoying. Any suggestions on the bolts that hold to roof . Two bolts about ten inches long holding to frame.Can they be adjusted for noise reduction by eliminating vibration and how much and tighter or looser? Have tried just tightening and loosening one with little or no effect but don't want to go too far....Help anyone?