My 93 MarineAir 16K BTU air conditioner died last year. Breaker popping when the compressor/water pump came on. Disconnected the pump, still trips. Measured continuity from compressor motor to ground...confident that the compressor motor is toast. Later confirmed.
For a year, searched the interweb's for experience in reaching/replacing the a/c unit. In the Mariner, the kitchen cabinets and the rest of the boat were built around the a/c unit. No good way to get to it. The interwebs were not as helpful as i hoped. Access is terrible.
We just complete the replacement of the unit, still some dressing to finish, and put the cabinet back together.
I'll be posting my experience, with pics - best i can, to share with the world. Probably less of a "how to", more of a how we did it, but Mariner owners may especially benefit.

Some quick notes:
remove the second shore cord, pop circuit breakers.
take the sink out
the cabinet wall needs to come out - Lots of screws from inside, and the corner trim needs to come off. I used a hammer & wood block to remove the trim-it is held in by small finishing nails.
Once the panel is off, there is much more room to work.
Inside the cabinet, there is a half wall that needs to be removed. There was a sneaky screw from underneath the panel that needed to be forced out...the rest is evident.

You will need wire cutters (for nylon straps), screw gun, and i highly recommend a screw gun adapter that is flexible. (i'll post a picture - at least 12", longer if you can find)

Most of all, you will need a helper, mine was great & i would still be in the hole without her help.

Hopefully i am able to upload pics in followup postings...not quite figuring it out now.
More to come.