Bad House Battery Problems
I recently had a problem with my furnace firing on our first outing earlier this year. I put it off as we have not needed it, but finally got around to figuring things out.
One morning early this season I had a low D.C. voltage code on the refrigerator, but shrugged that too because it never happened again and according to my battery indicator all showed good so forgot about it.
When I started troubleshooting my furnace it was throwing a limit/sailswitch code, so started there. Ended up replacing my sail switch as it didn't seem to be making contact in the closed position, and the furnace fired when I bypassed the switch. After installing the new switch, I still had the same problem.
Instead of going to the next safety, the limit switch and harder to get at, I started thinking simple and remembering that low voltage code early on in the season. I decided to check voltage on the house battery. Showing 100% while plugged in and no noticable issues throughout the coach, I was only showing 12.3v on my meter at the battery.
This less than ideal voltage was causing my furnace blower to turn at a slightly lower CFM, (even though it sounded normal) thus not closing the air switch which allows the burner to fire. New battery installed and everything is back to normal.
I'm on year #4 for my house battery, so not too bad considering we boondock a lot! Check your voltage at the battery, and don't rely on the indicator in the panel! A good battery should read around 14v. Hope this helps somebody out in the future!
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