Try turning off your dash AC before turning on the key to start.  If that eliminates the sounds further inspection is called for  There is a cooling fan under the front of your coach connected to the AC unit.  if there is something stuck in the fan blade cage, this could be your result.  

William and Edna:

It sounds exactly like what happened on my Ford Edge SUV.  There was an ‘HVAC Blend Door Actuator’ that went bad up under the dash which made some noise, didn’t do its actuating of the blend door and all I got was hot air on that side of the SUV.  The good news was that it was a typical issue, their were a number of YouTube videos on how to replace it, and the actuator itself was available on Amazon for about $35.00.  You could attempt to locate it yourself once you look it up and see what it looks like.  If you do, it should be relatively easy to replace (model # should be stamped on it, etc). Otherwise, any car mechanic should be able to quickly replace it if they have the part.

Or…..it could be something completely different.  Just a guess.

Mike