Agree about the motor back-fire possibility. I will be using a MOSFET to prevent that, and carry a few spare systems - they are cheap to build. Plus, as you no doubt understand, systems will develop and improve over time as we think of new features and control schemes. Presumably, you installed temp sensors in your refrigerator boxes and used the original Amel wiring from the compressors to the E51385, thereby bypassing that box entirely. That certainly would be the best approach, but I have not yet gotten there.
What is the ARDUM xxxx board? Don't forget, my system is still in the prototype phase. I looked on your website and could not find anything new, other than the running motor video.
Phantom A54 #44