RV Repair: Duo Therm Comfort Control Thermostat, penguin model, control thermostat

Question
I have a four button Comfort Control Thermostat that has failed
and have been informed that I will need to upgrade to the newer
five button; however, I'll need to change the circuit boards in both
AC units to accommodate the newer board.  I have the Duo Therm
620315 Penguin model and was wanted to know how difficult the
process might be.  

Answer
Hi Morris:
First I would spend a little more time to find a four button thermostat like the one in there. If that is not possible I would try to find another brand to replace the Duo Therm unit directly. As the last resort I would install the five button from Duo Therm. Changing that out may get pretty intailed. You will probably have to change the thermostats, circuit boards and wiring harness. Atwood Company makes a real good digital thermostat they claim works with all furnaces and air conditioning units. I would only do the five button Duo Therm upgrade as a last resort.
Bill