While the N641 wouldn't turn on I measured 12 VDC from the DC+ pos and DC- neg wires that connect to the PCB. After some time drying out of the rear vent area the N641 I noticed while opening the door the frig light turned on so I held the ON button and the N641 turned on and has been working good for a couple of days without any problems.
The N641 has only stopped working during severe rain storms with strong wind, never just when there's alot of rain, so during really heavy rain and winds moisture must be getting inside around the pcb.
One thing is even though I placed the pcb cover fairly tightly over the pcb I hadn't secured the pcb cover with screws so perhaps that's important that the cover is secured down tightly with it's scews?
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There is a side wall vent with louver 13" x 21" and a roof vent with cover ~16" x ~6". I haven't ever noticed water coming from the roof vent.
This time when the N641 shut off there was some moisture on top of the PCB cover but didn't notice any moisture on the PCB.
I think the problem is moisture is getting inside around and sometimes on the PCB itself. If moisture is getting in on the PCB coating it with some conformal coating doesn't seem to have effect other than reduces oxidation, mildew and corrosion which will occur in a few areas even though the pcb cover is screwed down.
It was last year I cleaned up any corrosion and green mildew which I noticed from the multi pin plug and a few other spots. After cleaning up real good I coated the entire PCB with a urethane conformal coating. Conformal coating are used to allow circuit boards to be used in wet locations.
