Here's info for a 1999 4100 SCA ... might help you - probably close if not the same.
Dometic Model 331566 115V 2.1 Amp Replacable with Dometic PMA1000 AC-5C-MD
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Paul Changes in L'Attitudes
1999 Maxum 4100 SCA
Location: Live in Mandevill, LA - Boat in Pensacola & Perdido, FL
Posts: 79
I'm the same way. On the 41 SCA the rear AC has a lot less water flow than the forward AC....so it clogs up a lot easier. I just had to run a new water line to the rear AC after 4 years or so. In Pensacola. Tried flushing it...gave up and ran the new hose.