Keith,
Monaco and SMC were no very concerned about coach owner access to the A/C service ports (charge ports). The vast majority of coaches have the factory service ports located under the front cap, close to the evaporator core. If you have a front mounted generator, they will usually be above the generator towards the driver's side of center. There are a lot of A/C shops that will install an extra set of service ports at the compressor for ease of recharging the system when extensive repairs are made.
However, there were a few coaches like some of the California 40s that SMC actually installed service ports at the compressor. On some rear radiator coaches the service ports were installed inline just before the lines leave the engine area, and the valves can only be reached from under the coach. So if you do not know the location of your A/C service valves, it will require some searching, but if they are not at the compressor, start looking by the evaporator core under the front cap.
Gerald