You would need to take the covers off the AC units inside the coach (4 screws- 1 in each corner). They have small round caps covering them. Once you get them off, you should see some long bolts going upward. These are the AC hold down bolts. Try tightening them some to see if the pads touch the roof. It may be that they didn't tighten them enough and you are getting a vibration. Don't over tighten though because you may ruin the gaskets if they are too tight.
Tom and Margaret
2014 Berkshire 390bh-60