Well, I said I was not going to make any more comments on the A54 fridge pump issues until I get the BLDC (brushless motor) design working, but I have to make a new confirmation that seems to corroborate with many who have provided advice about the technical issues regarding the Danfoss and E51385 pump output voltages.
I said that I was always getting 24 volts at the pump output. I also said that I bypassed the E51385 in the sense that I now take power for my 12V pump from the 24V supply connection in the engine room (using a DC converter) and installed a simple relay to turn that power on and off. I just checked the voltage across my relay, which is driven directly from the E51385 pump output. It shows just about 12 volts, even across the very small coil resistance in the relay. So, while I still see 24 volts under no load at the E51385 pump output terminal, I see it is switching to 12 volts nominal under load. It is also clear that the pump I have draws too much power to be driven directly from the pump output terminals on the E51385.
I cannot explain that voltage drop. Why do I see 24 volts at all if the compressors are sending 12 volts to the E51385 internal relays? I wish I had an internal schematic for the E51385. Not sure what turns on the 24-volt indicator lamp on the E51385 - has to be coming from the compressor somehow.
Anyway, it appears my E51385 is OK, and Scott, Oliver, and I are marching forward with the brushless motor design.
Thanks to all again,
Phantom, A54 #44