RV Repair: Furnace Heat when running on battery, furnace heat, limit switch

Question
My furnace works intially on battery and then once the temp is reached it kicks out, however when the temp lowers and the furnace kicks on after that point it no longer does so with heat, only the fan runs?  I suspect it is battery related? does it draw that much power each time the ignition switch kicks on?

Answer
It does sound like the battery might need to be replaced, but you also might want to check the sail switch and the limit switch, you can unplug both and use a jump wire to see if one of them is going bad. The heater itself doesn't really draw that much power, I would start by replacing the battery, depending on how old it is, then checking the two switches I mentioned (one at a time) feel free to follow up if these things are not the problem, good luck