[Richard]

Well, that’s good news as far as the transfer switch goes, but I am mystified now about why the outlets work on generator power and not on shore power. There is one more long shot test we should do while you have the cover off the ATS. On the backside of the contactors, you will see that they are actually wired together, and one of them has connections that continue to the 120V breaker panel inside. If the works on generator, doesn’t work on shore power situation is confirmed, then the backside connection that leads to the breaker panel should be checked in the same manner as you performed. It is doubtful, but in the interest of a thorough diagnosis, it should be confirmed. And so should the generator vs shore power behavior be confirmed.

So, for a second, let’s discuss how the 120v circuits that run through the inverter are configured. Circuits powered by the inverter which include the 120V water pump and the 120V air compressor, are wired through the inverter. The inverter has an internal ATS. If the inverter senses external 120V power from the shore or generator, it automatically switches to uses that power for the circuits. If the inverter does not sense 120v input, then it uses the 12v battery power to invert and provide 120v AC for the circuits.

There are breakers in the 120V box that control the 120v to the inverters. Those should be checked, and flipped a couple of times to make sure they are making good contact. You may have two since you have two inverters.

If you have access to the inverters, you could check the 120V voltage at the inverter input terminals. If you have 120V at those terminals, then you pretty much have narrowed the problem to the inverter(s). The error code you listed is pretty much a “inverter has lost it’s mind” code. But it is important to eliminate all possible causes before replacing an inverter.

I don’t recall if you checked to see if the inverter will actually invert off of your manually charged batteries to produce 120V power. Would you check to see if the inverter works of 12V power now that the house batteries are charged?

The fact that your house batteries will accept and hold a charge using a manual charger tends to eliminate a bad battery as a contributor to the issue.

I have run across others with wacky inverter malfunction that traced it to faulty temperature sensors. Some inverters have temp sensors on the batteries to prevent the charger from overcharging the batteries. I don’t know if your setup has temp sensors or not.

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And, HEY !, I know there are a bunch of electrical engineers on this forum. They have to have more insight than my redneck learning.

Anyone else have insight on this vexing problem?