Upgrading Penguin Duo-therm controller
You can retro-fit a new unit with a 5-button control board that makes the Penguin II reverse compatible with the CCC-1 (assuming that the boards are still available) as I have done it several times, but you can't fit the new control board to an older Penguin A/C unit to allow you to upgrade to the CCC-II.
Dometic is correct (as they should be....... It's their stuff..... They SHOULD know how it works!!!)
Lew Farber...ABYC Certified Master Marine Electrician...RVIA Certified Master Tech ...AM Solar Authorized Installation Center...AIRSTREAM Solar & Electrical Specialist