I had a dash ac problem and here is what Tiffin Service told me. You have a "computer" with lights on the drivers side front and passenger side rear. If you read the plastic sheet that identifies the fuse's and the lights on the computer, if the light in the front for the ac is lit, that means it is getting the info from the dash switch. If not, there is a problem from the dash switch to the computer.
I was told to check the connections to the switch if this is the issue.
Scott and Deanna Brandstetter
2014 Tiffin Allegro Bus 45LP
Domicile and current home, Jacksonville, FL