Airstream once again dances to their own tune. The list grows daily!!
These A/C problems have cropped up since the factory ditched the old plastic drain pan and joined the rest of the RV world in using the Dometic auxiliary drain kit with the external cups and hose arrangement for channeling the A/C condensate into the interior drain tubes and off the roof.
Only one problem............... these kits are meant to be used with 2 roof sealing gaskets
and Airstream uses only one.
This, along with the increased roof height of the '15 models and the accompanying increased roof curvature can create a 'moist situation'.
It is rather invasive to have to remove the roof A/C and it's accompanying gasket seal and replace with 2 new seals and re-install the drain kit, but that WILL solve your problem.
Barring the application of this 'full monte' fix, I would have the dealer wrap the offending data connections in self-sealing foam pipe insulation and tape the ends. That should keep the moisture away from the connections.