2013 2nd AC Unit

[Clemson1881]

Lynn, remove the A/C cover on the roof and check to see if the fan blades are clear. Often mud daubers will build a nest on one of the blades. What you describe sounds like exactly that. As far as the bolts being not tightened down they are not to be over tightened or you will collapse the seal and cause leaks. Giving them two or three turns each will not hurt.

[grayghost03]

Lynn, we have the same unit, but we have both AC's, there is no vibration at start up or any other time, living room unit very quiet, bedroom alittle louder.