[ccjohnson]

Only thing I can think of is to try to let heater warm the engine compartment. You might tape some plastic sheeting over the air vents to keep the heat in the compartment. Once it warms up if compressor functions ok you know it was ice. Get air tanks drained asap. Worst case you may have to call a roadside assist mechanic service. It may take an hour or 2 to met ice block if that's what it is. I would try to get heater under back end of coach if possible so that the heat will rise & thaw from the bottom up.