Not getting full 12 volt power to rear ac unit

[MassiveNightmare]

Rig is a 2017 3791RD

I noticed the other day that when I turned on my kitchen max air fan that the kitchen thermostat began to cycle on and off. (I have upgraded to the micro-air easy touch t-stat if it matters)

I checked voltage at the t-stat and only had 12.13

Checked voltage at the max air fan and had same voltage.

Figured out they are powered by the 15 amp fuse labeled "accessory" and pulled it to see what else it powers and so far all I can find is it powers both ac units, the kitchen max air fan and the radio.

Have 13.24 volts at fuse when grounded to door frame.

Have the same voltage at the front ac unit, but poor voltage at the rest of the accessories mentioned.

I'm pretty sure there must be a crappy connection somewhere, but where?

Front ac has a dead end connection going to it, max air fan connection feeds to the rear ac and then to the radio, where it once again dead ends.

So it would be my guess there is another splice in between the front ac and max air fan in the kitchen. Max air fan in the bathroom is connected via the bathroom lighting and turns off when a different fuse is pulled.

Any suggestions where to look next?