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Furnace issue

Hello everyone, I’ve done a bunch of digging for my issue and I’m looking for some experience in the matter. My furnace blower wouldn’t start and after some YouTube I decided to replace the delay relay. After doing so the furnace worked for 2 days and then after coming back to camper after a day away I realized my single deep cycle battery got down to 20% and my furnace wasn’t on. I tried turning thermostat off and on and nothing. I have 12v to the furnace. Question is..could the battery running low somehow affect the delay relay. Battery is at 50% now and I still can’t get it to turn on and it’s 50 degrees in here lol. Thanks for any help.


The battery, as mentioned may be the problem. However; the cage blower can sometimes get a mouse building a nest in it. Did you check the cage blower? If it does not rotate the heater shuts down.

Mark & Jan "Old age & treachery win over youth & enthusiasm"
2003 Fleetwood Jamboree 29

Explorer II
Explorer II
If you are looking for some experience in this matter. You already had it and now just need to make sure you learn from this event. First you should realize that the furnace blower uses a lot of juice, typically about 7 amps. That pull can run down a battery bank quickly. Many appliances such as a refrigerator or furnace will shut down when the battery voltage drops less than about 12 amps.

Another learning lession you may encounter is battery life. Even a deep cycle battery will not last long if you run it down all the way. I typically replace my car or RV batteries anytime I have an incident and run them flat.

Odds are your furnace will start to work again after you charge the battery more. If not I would pull the fuse and then reinsert. That will likely reset. Personally I would not even try that until the battery charge was about 12.5v or so. Again, I would also consider replacing the battery. If you plan on running the furnace a lot, you will need shore power or frequent charging from a generator or solar system.