Self contained marine air conditioning units should be located in the main cabin to be air conditioned. If you want to use one air conditioning unit to cool more than one cabin you can do this using a splitter to divide the duct and give you an additional outlet for the second cabin – see diagram above).
You also need to consider the return air from each cabin to ensure you get the correct amount back to the AC unit. If the AC unit is in the main (larger) cabin for example and you have a second outlet into a forward V berth you would need to put a louvered grill in the door of the V berth so that you are getting return air back to the saloon. If you had the unit located in the V berth with an outlet to the saloon it will cause reduce the temperature in the V berth before the temperature in the saloon has reduced significantly – in this case you may need a larger grill in the door joining the two cabins or even look at ducting air from the saloon back to the sleeping cabin.
Typical positions to install a marine AC unit would be under a settee, under a bunk, at the floor of a wardrobe or hanging locker or under the V berth.
To set up your system with one marine AC unit to cool two cabins set the larger cabin as the master and the smaller cabin as slave on our configurator.