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broadrun · 10-31-2015, 04:06 AM

We are camping in Hershey this weekend and the furnace was working all night. Good heat. I got up a while ago to turn the thermostat up a few degrees (from 61 to 63 degrees) and now it won't ignite - the fans runs but it won't even try to ignite?

The hot water heater ignites so I know I have flow of propane but not sure how much as the guage is not working on the test panel (reads full but I know it must be around 1/2 full). If the tank is low will that prevent the furnace from even cycling/trying to start? The reason I ask is because I had to replace a bad solenoid last summer and it fixed my problem but even with the bad solenoid it would click like it was trying to ignite.

No clicking or attempt to ignite now.

Thanks in advance.

-Rob

Dodgey · 10-31-2015, 04:16 AM

Something on the control side has gone. It's meter time, go through each stage of the wiring checking the various safetys, hopefully one of them has gone bad or it could be control board failure, though checking that is clean and dry also is a good idea, depending on model.
Our last RV did similar, turned out the over temp switch in the back of the unit had failed, luckiky we were at a show our RV tech was exibiting at and he happened to have one. Half hour groveling about under the refrigerator, furnance location, and heat was restored

NHRA225 · 10-31-2015, 05:35 AM

Which Furnace do you have and do you need a trouble shooting manual ?

shiggs68 · 10-31-2015, 06:30 AM

Low battery voltage will not allow the blower to come up to speed. Under that condition, it will not try to ignite but rather shutdown the blower.

The real question is does the blower shutoff or continue to run requiring you to work the thermostat to get it to try again. If it continues to run, then you have an ignition problem.

The Service Manuals are all online.

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broadrun · 10-31-2015, 06:32 AM

Update: I just tried it again and it lit up fine. Not sure why it would work intermittently like this? It seems like it comes on and stays on until it reaches desired temp and then the furnace will stop but the fan will continue to run to dissipate heat (which I believe is normal). Then the fan shuts off after a short time. Then, when the thermostat detects a drop in temp, the furnace kicks in again but this time the fan just runs and runs with no ignition attempt.

So maybe it has something to do with the thermostat?

broadrun · 10-31-2015, 06:34 AM

Quote:

Originally Posted by NHRA225

Which Furnace do you have and do you need a trouble shooting manual ?

Not sure about unit manufacturer but will check and update this thread. I downloaded a great troubleshooting manual already and thanks for asking.

captw3 · 11-01-2015, 07:46 AM

I had the same thing happen. I read the led blinking code and found low air output had caused a overheating condition. Took the rug off the living room heat register and let the unit cool down. Restarted fine and no more problem. (Or rug)
Rick

marcham · 11-01-2015, 07:49 AM

Sounds like a failure of the sail switch when it's warm. If you wait 1 hr will it come on then?

shiggs68 · 11-01-2015, 05:39 PM

The fan continuing to run is an indication that it tried to ignite the burner but it didn't succeed. This is called lockout. The thermostat needs moved to a colder setting and back to reset the lockout and cause it to try again.

With that said, it is not the sail switch. It is probably mis-adjustment oh the igniter or the igniter needs cleaning as it is not detecting the flame. Your manual should explain the process.

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broadrun · 11-01-2015, 08:28 PM

Actually, the symptoms are more like marcham mentioned. Once it is off for an hour or so it will start back up and light without any problem. Also, when the problem occurs it doesn't ever cycle the igniter. No clicking. It must be the sail switch.

shiggs68 · 11-02-2015, 05:06 AM

Quote:

Originally Posted by broadrun

Actually, the symptoms are more like marcham mentioned. Once it is off for an hour or so it will start back up and light without any problem. Also, when the problem occurs it doesn't ever cycle the igniter. No clicking. It must be the sail switch.

Since your furnace goes into lockout, the sail switch is working. If the sail switch was not working, the fan would shutdown within about 30 seconds.

Depending on the model, the high-temp limit switch will cause the same problem. If tripped, it will not attempt to ignite. When the furnace is in this non-ignite condition, you can test the high-temp limit with a meter at the wires connecting to the circuit board. Your manual will define which wires.

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broadrun · 11-02-2015, 06:15 AM

Quote:

Originally Posted by shiggs68

Since your furnace goes into lockout, the sail switch is working. If the sail switch was not working, the fan would shutdown within about 30 seconds.

Depending on the model, the high-temp limit switch will cause the same problem. If tripped, it will not attempt to ignite. When the furnace is in this non-ignite condition, you can test the high-temp limit with a meter at the wires connecting to the circuit board. Your manual will define which wires.

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That sounds like it might be the ticket. I'll be ready to roll the next time this happens

Thanks to all.