I don't know if this will help, but I feel your pain.
I have a 2008
Hunter 49 that went through quite a bit of AC/Heat
work in the last year. I have three units (forward berth, main
salon, and aft cabins). The original manufacturer is apparently gone, but the replacement stuff from Dometic worked fine. In my case, the problems were several, but the main one had to do with the
control panel, and not having any feasible replacement that would communicate with the main blower and unit in the
salon. I replaced all three units, including the control
panels, and now the entire system works as it should. I tried to just do little incremental
repairs due to the cost, but now I'm glad I did it. It looks like you are in the same areas as me.
So, Sherwood
Marine Systems in
San Diego handled it. Highly recommended. Good luck.