According to the service manual you check that there is AC at the outlet, check the fuse and, if the fuse is OK, you replace the circuit breaker.
I had to do it on mine a couple years ago and I "assisted" Dave Hiatt a few weeks ago at Havasu. Both of us used an aftermarket replacement board from a company called "Dinosaur"
The fues you are looking for is on the circuit board that is behind a black plastic cover. If it blows or doesn't firmly fit the fuse holder you will get the "No AC" code. Getting to the cover and removing it is not real easy.
I have the service manual in a .pdf and can email it to you. (On edit: I sent the service manual file to Tim Bentley. He will have it on the BAC Website under "Coach Assist" in a few days.)