Yes. Getting the power to run it may be another story.
My 21ec has the later of two factory ac installation types. The first, I believe, was a true 12-volt unit, which apparently did not have enough capacity to do the job.
They at some point switched to the kind I have. It is actually a 110-volt unit, operated by an inverter. It is made by Dometic and seems to be of good quality. I think it has only 3500 BTU output. On a really hot summer day, this is marginal. I would suggest at least 5000.
The installation is not too bad. What you get is a self contained unit very roughly 12 in high that sits on a roughly 18 in square base, which is the drain pan for the condensate. The only reasonable place to put it is under the sink/stove area.
It draws return air through the louvered doors leading to that space. They give you a flexible duct to lead the cooled air to a suitable spot. In my case it is on tope of the little shelf to the left of the mate's seat. You will need to make a hole in the hull and install a thru-hull for the condensate drain.
You will also get a pump to pump seawater through the condenser in the unit. You will need a thru-hull, sea cock, and strainer to supply water to the pump, as well as a discharge fitting for the warmed sea water. In my boat they put the pump in the little storage area to the left of the head.
Electricity - This setup will use 500-600 watts. You can easily get this out of the engine alternator when cruising, but you definitely can't get it out of the stock 20-amp battery charger on shore power. They put two extra batteries in my boat that are a joke. They will run he AC for about 30 min. I am contemplating putting a y cord of some sort on the AC so I can plug the AC directly into shore power.
Hope this helps. Check Dometic's web site.
Larry