I thought its a common alarm output, most likely for the bms. A clogged filter switch could probably trigger the output. But I would have never opened the door for the customer to think this is standard practice. Awesome job by the way but for me and my customers, I’m like do it right or don’t do it at all. Because you know they’ll expect you to modify parts or whatever the next time.
Just me, but if the customer can afford to have that unit,, then you shouldn’t have to resort to modifying the circuit board. Also remember the guy coming behind you without a revised wiring diagram.
