Lost power to gauges, a/c fan

99 Freightliner FLD120
VIN 940979
60 series Detroit

We were sitting in line to unload at the mill and the truck gave a sudden "start/jump" and we lost power to the gauges and a/c fan. Still have dome light and cig lighter plug operational. It will still crank and run if you kill it. We have checked the key switch and have fire to all connections with it on, I have checked inside the fuse/breaker panel and haven't found a bad relay yet. In the breakers on the right hand side of the panel, there are 5 in a row at the top. All of the breakers were hot EXCEPT the first one. The wires that I could identify that were attached to it were 14, 912 and 279(unsure of this one). 14 runs down to a relay at the bottom of the panel. At this time, that is the only thing I have identified that MIGHT be the issue. Am I in the ballpark or should I be focusing elsewhere?

Appreciate any help with this. It's hot w/o a/c in Louisiana!

 

I will look that direction too