It sounds more like you have an antenna problem and not the TV. What kind of roof top OTA antenna does the RV have. Do you have a switch box to select between Ant, Cable, Aux, ect.? When doing a new scan for TV channels are you sure you have selected TV or Antenna and not Cable? There is also certainly an antenna booster in the coach and if it is not on or not operational you will not pick up much of anything. This is usually a wall plate with a teeny tiny light on it. On the OTA amp is on. No light and is the correct setting if you are hooked up to campground cable. Some RV's use a separate switch or a button is located on the connection box mentioned above.
Let us know what you find.