Totally concur with Stu ! Join the C36 assoc.
Its a very valuable resource. Not only will get upgrade information, but they are very active in notifying the users of recalls, potential problem areas and issues that might come up. Also you get a quarterly magazine the "Mainsheet" from Catalina with story, tips, and Technotes for all the Catalina Class boats. Each issue is worth more than just association fee.Here is a link to joining the associationhttp://www.catalina36.org/application.htmAfter you join you can also get a hard copy of **all** the past technotes on the C36 from all those years. It includs all drawings/photos from past issues of Mainsheet, is currently available for $40.00 U.S. (including shipping).http://www.catalina36.org/tech_tips.htm(This site only has the verbage from the tech notes and only from 1998, you'd have to order the complete back issues from the C36 assoc from the website above)Also the C36 website a veritable wealth of information over there, but just to whet your appetite here are a few links on what some people did for putting in A/C on their boat and posted information on the web.http://www.catalina36.org/article_airconditioning-install.htmhttp://www.imagestation.com/album/?id=4290064707http://www.imagestation.com/album/?id=4289176283http://users2.ev1.net/~barr/c36ac.htmBut to answer you question directly - about 55% of the people put the A/C unit in the space under the seat in front of the galley sink, about 40% put it in the v-berth (older boats without forward tank would do this more often) and the other 5% find "other" places for it. The big issue as you can imagine is routing the ductwork and minimizing the spaces you cut into.