First off, I want to thank the members for their helpful information regarding my Penguin II install problems. Dometic does not have a customer technical support division. Only for dealers. I got lucky and spoke to Sharon on one of their phone numbers. She was very helpful and gave me the exact part number for the new thermostat that would communicate with my new unit. So for my contribution to the RV community, if you are replacing an old a/c unit and your thermostat is a 5 button Duo Therm and the direct replacement unit is a Penguin II you will need to either replace the control board in the unit or replace your 5 button thermostat with a Dometic 3314082.011 as per Sharon.