I have dometic rooftop ac. Worked last year when stored . This year ac doesn't work . Tried new t stat and nothing happens. Touch green wire to any other function wire and that function starts.

SOURCE: Dometic Rooftop RV Air Conditioner

Possible bad capasitor, or seized motor

SOURCE: Circuit Breaker and Dometic Rooftop RV Air

Since your RV A/C works O.K. when plugged in to the land line and the trip happens when you run it on your generator the problem may be related to the generator output. It is possible that the power being supplied by the generator is not handling the surge when the A/C starts. Starting Amperage on start up is about 5 times the running Amperage for about 3 seconds until the compressor comes up to its rated speed.

SOURCE: We have an older model (58SG100251) installed in the attic. With the thermostat set & turned on nothing happens. A new blower motor was installed last year.The t/stat is a ritetemp digital. I,ve c

Possible fan relay is defective, does outside unit come on ?

SOURCE: Relay (?) sticking Dometic RV rooftop AC

Go up on the roof of the unit and remove the AC Shroud. With the unit running, see if you can pinpoint where the sound is coming from. The only thing on the entire AC that would make that much of a vibration would be the fan motor. Not sure what would cause the fan motor to do this. The compressor may do that but only if the windings are bad and then it would not be cooling.

SOURCE: How to identify the btu of rooftop AC unit

ANY # DIVISABLE BY 12. MODEL HAS  12-24-30-36-40-48-54-60 12 1 TON 24 2 TON 30 2 1/2 36  3 TON 36.00 BTU 40 3 1/2 48 4 TON 48.00 BTU 54  4 1/2 60 5 TON   60.000 BTU