bubba Posted January 1, 2010 Share Posted January 1, 2010 I have a 1979 starduster 21ft. with a coleman 4312 furnace. It seems to work fine when i have the motorhome plugged in. I checked the voltage at the house battery and it's at 12 volts, lights bright. Pilot light works fine, crank up the thermostat and nothing happens. no blower, burner doesn't light.. any ideas what could be causing the problem? Also would love to find a manual for the furnace. thanks Quote Link to comment Share on other sites More sharing options...
Maineah Posted January 1, 2010 Share Posted January 1, 2010 Without the blower it will not light. Try removing the thermostat and twisting the wires together that will eliminate the thermostat if that does not work you are probably lacking power to the furnace. Quote Link to comment Share on other sites More sharing options...
bubba Posted January 2, 2010 Author Share Posted January 2, 2010 Without the blower it will not light. Try removing the thermostat and twisting the wires together that will eliminate the thermostat if that does not work you are probably lacking power to the furnace. I would think that the thermostat is ok, as the unit works fine when i am on shore power. Just wondering what the main diff is between the two, (battery/shore power). Doesn't the power inverter/converter just send 12v to the furnace? or does the furnace have a 110v circuit? Is there a relay or something that switches between the 12v and 110? or one that switches between the 12v(from battery) and 12v (from the converter)? Just doesn't make sense to me why it works on shore power and won't work on 12v...when the battery is fully charged. Quote Link to comment Share on other sites More sharing options...
Maineah Posted January 2, 2010 Share Posted January 2, 2010 Good question, the converter makes better then battery voltage but that does not explain what it won't do any thing on just the battery. If the fan runs too slow it won't light and that would explain why some time plugging in the camper will make it work but not in your case because it just does not run at all. I think it would be time to look at your converter panel wiring and see if they have not done some thing strange like hook the heater to the converter and not the fuse panel do it your self wiring by a not so good do it your selfer can produce strange results. I would look into grounds too. Do your lights get brighter when you plug in the converter? Quote Link to comment Share on other sites More sharing options...
bubba Posted January 21, 2010 Author Share Posted January 21, 2010 Good question, the converter makes better then battery voltage but that does not explain what it won't do any thing on just the battery. If the fan runs too slow it won't light and that would explain why some time plugging in the camper will make it work but not in your case because it just does not run at all. I think it would be time to look at your converter panel wiring and see if they have not done some thing strange like hook the heater to the converter and not the fuse panel do it your self wiring by a not so good do it your selfer can produce strange results. I would look into grounds too. Do your lights get brighter when you plug in the converter? Well i do believe that i have found the problem. I cleaned all the electrical connections and got the furnace to work. Next problem with it....lol I think i need a new thermostat, it doesn't turn on till i have it above 80 degrees, and then when it's on 90 it will stay on for about 30 seconds and turn off. then turns back on in a little while, but never even comes close to getting the camper even to 60 degrees. Won't turn on at all if i have it set to 80 degrees. Will any 12v Thermostat work with it??? Quote Link to comment Share on other sites More sharing options...
Maineah Posted January 21, 2010 Share Posted January 21, 2010 Well i do believe that i have found the problem. I cleaned all the electrical connections and got the furnace to work. Next problem with it....lol I think i need a new thermostat, it doesn't turn on till i have it above 80 degrees, and then when it's on 90 it will stay on for about 30 seconds and turn off. then turns back on in a little while, but never even comes close to getting the camper even to 60 degrees. Won't turn on at all if i have it set to 80 degrees. Will any 12v Thermostat work with it??? Sure any thermostat that you would use for your home furnace will work fine I put one of the programable ones in mine so it warms up the camper in the morning and sets back at night. Quote Link to comment Share on other sites More sharing options...
bubba Posted January 25, 2010 Author Share Posted January 25, 2010 one quick question about a thermostat. will any of them work as long as they are 12v? Quote Link to comment Share on other sites More sharing options...
Maineah Posted January 26, 2010 Share Posted January 26, 2010 one quick question about a thermostat. will any of them work as long as they are 12v? Yes they are nothing more then a switch just on and off voltage is not an issue so one for a house furnace will work fine. A lot of them will have a differential setting so look at the directions and set the differential as high as you can that way your furnace will not cycle as often most home are set around 2 degrees try your camper at 4 (I think that's the max). Quote Link to comment Share on other sites More sharing options...
bubba Posted January 27, 2010 Author Share Posted January 27, 2010 thanks good to know..... Quote Link to comment Share on other sites More sharing options...
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