Furnace runs for the first night....then won't start up in the morning?
So I'm stuck with an issue and am about to troubleshoot yet again to fix this problem, but I wanted to see if anyone else could throw in some nuggets of information gold for me....
I went camping on May long and ran the furnace with no issues on my 2006 Forest River Yearling Tent Trailer. It ran all the way through the night, and in the morning I turned it down low to 16C so as not to run my propane and power dry. The next evening, the furnace doesn't work. When the thermostat is turned over to engage the furnace, the blower runs its 20 second cycle to clear the combustion chamber and then turns off. The DSI does not "click" and ignite the burner. I boosted the battery with my truck and that was able to turn over the furnace on the first try and ignite the burners and when I took it off the truck it ran through the night again, but the next day it would not start up again after the burner went out. Long story short, the battery I was using had two broken cells so it would make sense that it had a low voltage issue and was not able to turn the blower to its 75% rpm, not activating the sail switch, etc. Oh and plus the charge (from my multimeter) was showing 11.5 amps during this period.
HOWEVER, after the weekend I replaced the battery with a high quality marine battery and an intelligent charger. Fully charged and ready to go, I took it out again this weekend. First night, no problem. Blower turns over its cycle, burners ignite and we're off to the races. Heat all through the night, and again in the morning I set the thermo to low (not off). Next evening comes around, and NOTHING. Same crap. Blower goes through its cycle and nothing else happens. Multimeter shows a charge of 12.7 amps on the battery. I cycle through numerous times and same cycle happens with no burner ignition. The fix came when I charged the battery to full strength again and, oddly enough, it worked on the second cycle.
I am going to be taking the relay board in to see if its faulty, but I am wondering now if it is a faulty sail switch that isn't getting closed. I just don't understand why it works great for the first night and then craps the bed the next. It makes it really hard to fix things when they work when you test them at home and then they don't work in the field. The wife is not happy.....