Yes, the problem is the switch/circuit board. Seems it is not all that uncommon that condensation forms on the cover and drips on the circuit board and kills it. I by-passed the switch/circuit board and the fan ran ok. I am waiting on a circuit board to be delivered now.
My fan is a Maxx Fan P/N 4301 and the board P,N is 10-4301K-V1.6 . If you have a different fan, the board P/N may be different.
Attached is a pdf of the parts list and below is phone number for Mike who is helpful in getting part. They don't have the particular board I need in stock, but Mike said he had a good used one that had tested out he could send me.
Technical Assistance Coordinator
RV PRODUCTS, a division of Airxcel, Inc.
3050 North St. Francis
Wichita, KS, 67219
2015 Thor Vegas 24.1 in Ocala