Furnace

[Flintlock]

Hello, our furnace has been operating intermittently. Sometimes, (usually 2-4 times in a 24 hour period) the fan and furnace will not come on when the tempature drops below the setting. If you turn the thermostat off and back on the fan will usually come on and and the furnace will fire, but sometimes all you hear is a click at the box near the rear ac unit. If you then go outside and turn the reset switch off and back on at the furnace the fan will start and furnace will fire.
I have reset the thermostat, and even installed a Dinosaur circuit board. There is 13.11 volts at the furnace.
Domestic thermostat and Atwood furnace.
Any help would be greatly appreciated.

Thank you,
Bill

[dieselguy]

Mentioning that most times turning the thermostat off and then back on may be pointing to your problem. (thermostat) There also is a time delay relay that 12 VDC flows thru off your thermostat. It causes the several second delay before anything at all happens once you turn on your furnace. It may be flakey. You may have a bad 12 VDC ground. You may have a loose wire somewhere.

[Art-n-Marge]

The only thing I can offer is that 13.11 volts sounds okay because a "12v" battery typically reads 12.5-12.8 volts, and 13+ volts when it's being charged. I'm guessing you measured the voltage without disconnecting the battery and your rig is plugged into shore power and the onboard converter is charging the battery which can cause a 13.1 reading.

For example, disconnect the battery cables and the reading should drop to about 12.5 to 12.8 volts.

So the voltage looks good and your problem is at the furnace which is a 12v device on or off shore power.