There isn't a Coach Care facility in Las Vegas (there is on in Sparks, just off of I-80), only a Cummins service facility that does mostly trucks and might work on the engines of MHs but usually do nothing else.
The radiator isn't part of the engine, it is designed by the chassis manufacturer. Most Coach Care facilities will do flushing, etc., but not all. It is a question of it being harder to work on coaches than the big trucks that is their main business, so they often just don't want to get involved in doing that. Sort of depends upon how busy they are, how experienced their help is, etc.
Barb