We installed my Trane 2 ton system about 6 years ago. To level and try and eliminate vibration, I placed 4 or five rubber feet under condensing unit. A few months ago, Brighthouse (tv) people showed up, moved my unit a little bit because of space restrictions, knocked my feet from under unit, and so the vibrations have begun. I've tried putting the feet back under but doesn't seem to shim correctly for any length of time. Now I have just removed feet entirely, thinking this is how it should be to start with. Also I originally shimmed because my concrete pad is a little tilted. Unit now sounds like a 2 stroke engine, not completely humming but almost like 2 quick sounds in one. I was thinking of strapping some angle iron or something on four corners of unit to try and stabalize some more. Any experience with this problem ?