Furnace not working

[BScoot]

Hello all. We are new to the RV world. Just bought a 2020 Jayco 264BHW. First trip out, three nights in we climbed just above 5,000 feet. The following morning it was a bit chilly. Tried to turn on the furnace from the thermostat. No fan, no clicking, no heat. Opened up manuals and went through the limited troubleshooting. No joy! Basically we decided there was a reset switch, ( not accessible in this model). We were in a poor cell area but finally got through to tech support. Walked us through everything we already did and arrived at the same conclusion. We will need to uncover the switch, ( remove sofa and box over furnace).
At home, I cut a hole in top of box and flipped the switch. This cut power to thermostat. So, still now furnace.
Any ideas would be great!
Thanks!

[JimD]

For the furnace to work 4 things are required - +12 volts, ground, +12 volt turn on signal, propane. The normal sequence for a furnace is for the +12 volt turn on signal to cause the blower motor to energize via the control board. Since you stated that nothing happens when you turn your thermostat on, you can eliminate the propane requirement at this time.

Before continuing make sure the blower wheel is free to rotate. For the furnace to light it has to sense air movement. If something is preventing the blower from turning, that would prevent operation.

You should use a multimeter to measure the voltage at the furnace. Verify you have a solid 12 volts going in. Measure from the +12 volt wire to the ground wire and not the frame. If there is no voltage you may have a blown fuse in the fuse panel. There may also be a fuse inside the furnace but that is just a guess. You may have the 12 volts going in but if it has an internal fuse that is blown, you need to fix that.

Once you verify that you have good supply voltage you should check the wire going into the furnace that supplies the +12 volt turn on signal from the thermostat. There should be a solid 12 volts on that line when the thermostat calls for heat. No 12 volts could mean a thermostat problem.

If all voltages are present and the unit does not turn on and there is no blown internal fuse, odds are the problem is internal to the furnace.

[Rustic Eagle]

BScoot,

Welcome to JOF

Originally Posted by BScoot

snip.....At home, I cut a hole in top of box and flipped the switch. This cut power to thermostat. So, still now furnace.....snip

When you preform the furnace 'reset' try this: first turn the wall thermostat 'off', then flip the reset switch to the 'reset' position waiting 15-20 seconds before flipping back to the 'on' position...., then turn 'on' the wall thermostat.

Depending on the type of furnace fault being incurred, the furnace will make 3 attempts at starting, then a 'reset' is required.

My problem was a bad 'sail switch'..., furnace would start the initial fan cycle, but would shut down after 15 seconds without intimating taking place. I could get the furnace to run by tapping on the furnace near the sail switch during initial startup..., but that technique didn't last long, I replaced the sail switch.

I agree about the difficult access of the reset switch, I had the same condition and incorporated a similar access point through the wood enclosure as well. Jackknife sofa removed in photo...:



Bob

[BScoot]

Originally Posted by JimD

For the furnace to work 4 things are required - +12 volts, ground, +12 volt turn on signal, propane. The normal sequence for a furnace is for the +12 volt turn on signal to cause the blower motor to energize via the control board. Since you stated that nothing happens when you turn your thermostat on, you can eliminate the propane requirement at this time.

Before continuing make sure the blower wheel is free to rotate. For the furnace to light it has to sense air movement. If something is preventing the blower from turning, that would prevent operation.

You should use a multimeter to measure the voltage at the furnace. Verify you have a solid 12 volts going in. Measure from the +12 volt wire to the ground wire and not the frame. If there is no voltage you may have a blown fuse in the fuse panel. There may also be a fuse inside the furnace but that is just a guess. You may have the 12 volts going in but if it has an internal fuse that is blown, you need to fix that.

Once you verify that you have good supply voltage you should check the wire going into the furnace that supplies the +12 volt turn on signal from the thermostat. There should be a solid 12 volts on that line when the thermostat calls for heat. No 12 volts could mean a thermostat problem.

If all voltages are present and the unit does not turn on and there is no blown internal fuse, odds are the problem is internal to the furnace.

Thanks for the info. All that will require time ( which I have little of) to remove the sofa and the box built in over the furnace. Question though, if the switch cuts power to the thermostat, that at least means the circuit to the thermostat is complete, right? I did check fuses and the breaker. I'll have to find time to run through your suggestions!

[BScoot]

Originally Posted by Rustic Eagle

BScoot,

Welcome to JOF



When you preform the furnace 'reset' try this: first turn the wall thermostat 'off', then flip the reset switch to the 'reset' position waiting 15-20 seconds before flipping back to the 'on' position...., then turn 'on' the wall thermostat.

Depending on the type of furnace fault being incurred, the furnace will make 3 attempts at starting, then a 'reset' is required.

My problem was a bad 'sail switch'..., furnace would start the initial fan cycle, but would shut down after 15 seconds without intimating taking place. I could get the furnace to run by tapping on the furnace near the sail switch during initial startup..., but that technique didn't last long, I replaced the sail switch.

I agree about the difficult access of the reset switch, I had the same condition and incorporated a similar access point through the wood enclosure as well. Jackknife sofa removed in photo...:



Bob

Thanks for the reply. By the time I went back out, it was too hot and the furnace would not work even IF it was working!
I'll try the reset again when it is cooler.
Like the door and vent!