And, btw, I gotta kinda agree with Doug on this one. An RV tech is likely gonna know alot more about what goes where than a normal HVAC person. And to be honest, I'm not sure I'd like any of the HVAC guys from our usual company out there climbing around on our RV's roof. No offense to them.
Last time we had problems with the AC in our TT, it like to drove us nuts trouble shooting it. Turned out that it was just a loose connection. Every time we started up the unit, it would suck in air, the filter would move slightly upward and the wires would be forced apart just enough to make the unit quit.
Could be something as simple as that.