When testing out my furance (Suburban DD17dsi) ahead of cooler camping this fall, the fan was coming on but the igniter was not clicking on. When on shore power it was working fine and lighting, but on battery power the fan was noticeably slower and pulsing a bit faster and slower. I also noticed that when the front screen/cover was removed, it would start on battery, but with the cover back on it wouldn't. I tracked down that the cover was slowing air movement enough that the sail switch was not being tripped and that was preventing the igntor/gas valve turning on. I am seeing over 1V drop at my charge controller, about half way between my battery and the furnace when the fan turns on. I also notice the voltage wavering approx 0.2V in sync with the blower speed pulsing (when the fan speed increases, the voltage reading increases). It is 14ga wire from battery to the furnace - maybe 8ft away. Is this likely a wire gauge issue, or is the blower motor going? Or something else?