[TexasCamper]

The AC on the roof makes condensate which finds the path-of-least resistance across the roof and drips down a side and off the trailer. Normally if your TM isn't perfectly level the dripping will form at the lowest corner.

Now also on your roof are many spots that are caulked. There is a seam that runs down the middle of both front & back shells, and this seam has a center strip over it, and this center strip has caulking on both sides. This caulking wears away and the strip needs to be recaulked every few years. There are also caulking around seams for the sun-windows and ceiling fan.

I suspect the condensate is running off your roof and finding a seam that no longer has good caulk sealing it. Once the water is inside, it is shorting out parts of your wiring system and blowing fuses. I suggest you do a thorough inspection of your shells and recaulk anything that doesn't look right.

P.S. the 'humming' you mentioned at the AC/DC inverter is probably normal. I think there is a small fan that kicks on and off from a temperature switch.

Good luck,
John