Furnace won't start

[bjrogers]

Greetings. 2020 390RK. Went to turn on furnace due to cooler temps. Thermostat "clicks" in Heat mode, but furnace motor does not turn on. Absolutely nothing happens even after multiple attemps. Checked fuses, battery disconnect, have plenty of propane. Wondering what I'm missing. Thanks for any assistance/help. BJ Rogers

[howson]

Greetings. 2020 390RK. Went to turn on furnace due to cooler temps. Thermostat "clicks" in Heat mode, but furnace motor does not turn on. Absolutely nothing happens even after multiple attemps. Checked fuses, battery disconnect, have plenty of propane. Wondering what I'm missing. Thanks for any assistance/help. BJ Rogers

One possibility when there's no response is the control board may be "seeing" the sail switch stuck closed. It must see the switch open to start the fan and then continue with the rest of the start up sequence.

See https://gdrvowners.com/forum/operati...on-the-furnace and https://gdrvowners.com/forum/operati...ce-sail-switch

Howard

[bjrogers]

One possibility when there's no response is the control board may be "seeing" the sail switch stuck closed. It must see the switch open to start the fan and the continue with the rest of the start up sequence.

See https://gdrvowners.com/forum/operati...on-the-furnace and https://gdrvowners.com/forum/operati...ce-sail-switch

Howard

Thank you! I'll check this and see.

[bjrogers]

Thanks for the help so far. Opened up furnace and easily found sail switch. Did as instructed on suggested forum posts, but still nothing. Should I replace the sail switch or is there another possible problem I need to check. Switch is "open" but furnace does not turn on. Thank you!

[TucsonJim]

If the motor is not turning on, it won't be able to activate the sail switch to complete the sequence leading to ignition.

1. So, if there is no motor, I'd suspect you have a problem with the 12V electrical supply or the control board. If you have good battery voltage, then it's likely the control board. Dinosaur brand supposedly makes excellent replacement control boards.
2. If the motor is turning on, but there is no clicking from the igniter, then I'd suspect the sail switch is sticking and possibly needs replacing.
3. If you're getting motor activation and hear the igniter clicking, it could be a propane delivery problem. Try turning on all the burners on the cooktop and make sure they have a high bright flame. If the flames are low or go out, then trouble-shooting will be needed on the propane side of things.

Jim

[bjrogers]

If the motor is not turning on, it won't be able to activate the sail switch to complete the sequence leading to ignition.

1. So, if there is no motor, I'd suspect you have a problem with the 12V electrical supply or the control board. If you have good battery voltage, then it's likely the control board. Dinosaur brand supposedly makes excellent replacement control boards.
2. If the motor is turning on, but there is no clicking from the igniter, then I'd suspect the sail switch is sticking and possibly needs replacing.
3. If you're getting motor activation and hear the igniter clicking, it could be a propane delivery problem. Try turning on all the burners on the cooktop and make sure they have a high bright flame. If the flames are low or go out, then trouble-shooting will be needed on the propane side of things.

Jim

Thank you, Jim. I'll keep troubleshooting!

[howson]

bjrogers

Below is the sequence of operation.

So the first step, as Jim suggests since the motor doesn't start and it's not the sail switch, is to check for proper voltage. The troubleshooting chart is further below.

Go to https://myrvworks.com/manuals/ and you'll likely find the service manual for your furnace (that has the information below).

Howard

[Scott'n'Wendy]

I think you have a thermostat problem. Your furnace is doing nothing....probably not being told to do anything by the thermostat. Or has no 12vdc. I don't know what kind of thermostat you have, but you need to jumper the wires that call for heat. Then if nothing happens, you know you have a furnace problem.
Do you know how to use a meter?

[sportsdad60]

Our 2021 310GK-R experienced the same thing in Texas this past winter. There was a mobile RV guy in the park and he was kind enough to come over free of charge and trouble shoot it.
Turned out it was a bad board. He charged us $40 to replace it as the furnace was still under warranty.

[Jlawles2]

Tot he OP, one thing that has caused issues in the recent past has been wiring at the thermostat. Several people have found the wires in the thermostat connector dislodged. You will hear the stat "CLICK" but since the wiring had become dislodged (disconnected) the signal has no where to go.

Verifying signal voltage and input voltage to the furnace will help determine if it's truly a wiring issue or something more involved such as a board. As the furnace should be 12V, caution is advised when checking voltages to avoid the possibility of shorting the wiring, and possibly the inspector getting shocked. Please be cautious if you do this yourself.

As always Howard has supplied a good trouble shooting guide for the furnace.

[colan]

When reading Howard’s first response, sail switch, my initial reaction was no. Then a couple of milli-seconds later it was certainly a possibility.

The first thing the control board does when the thermostat says give us heat is check the sail switch. If the sail switch is closed at this point there is a problem, it should be open as the fan isn’t running.

If the furnace blower doesn’t run at all a bunch of possibilities:

1. 12v power and connections
2. sail switch closed
3. control board
4. dead motor
5. thermostat

items are not listed in order of likelihood.

Typically there are four wires to furnace. Positive, negative, and two thermostat wires usually blue. If you tie the two blue wires together goung to the furnace it should run. If the furnace runs with the blue wires connected the issue is upstream from the furnace.

[bjrogers]

Thank you all! Still working the problem....