The change over relay is very very week. When too much current is drawn thru it it burns the relay contact pads breaking the circuit. There is no clue that this has happened. Plugging in up front will reset it. I had the same problem on the first couple of uses of our new 2012FB. Was just infuriating. Replaced the cheesy relay with a properly rated and designed change over contactor. I documented the whole replacement process in an earlier thread. Airstream is fully aware of the problem and they should replace it free of charge.
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2015 30' FC Bunk, Dual A/C, Full Awning, RV550, Sleep Number, ProPride, Nokian Rotiiva AT 15" Tires
2015 Chevrolet 2500HD 4WD Duramax/Allison LTZ Crew Cab Short Bed, Huper Optik, Bull Dog Spray In, Roll-N-Lock, Full Amsoil, Denali SoundBomb, Yakima