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Old 09-19-2021, 02:52 PM   #1
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THOR #21941
Furnace not working

This morning I turned on the heater and the fan came on, then the propane started. After about 15 seconds, the propane stops. Propane starts back up in about 0 seconds only to turn off again. Heater set to 80. (Inside is 60). Fan on auto.

This happens two or three times and the fan turns off. If I turn off the heater, the fan makes a weird noise and a slight amount of air comes out of the vents.

Did my thermostat take a dump?

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Old 09-19-2021, 06:13 PM   #2
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Are you connected to a full propane tank with the valve fully open?

If your cook top works OK then you have sequence issues or board issues

Don't really sound like a thermostat

Long time since I have had propane furnace so not much help
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Old 09-19-2021, 06:23 PM   #3
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THOR #16471
The blower fan needs to push a certain amount of air to operate the 'sail switch' which in turn allows the gas to flow for a flame. If the fan motor or blower is being inhibited in any way (weird noise) then the sail switch may not be operating like it should and you will freeze....

Open the hatch outside and watch/listen to the unit operating. While there, get the make/model info.
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Old 09-19-2021, 06:31 PM   #4
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Quote:
Originally Posted by waynetaylor55 View Post
This morning I turned on the heater and the fan came on, then the propane started. After about 15 seconds, the propane stops. Propane starts back up in about 0 seconds only to turn off again. Heater set to 80. (Inside is 60). Fan on auto.

This happens two or three times and the fan turns off. If I turn off the heater, the fan makes a weird noise and a slight amount of air comes out of the vents.

Did my thermostat take a dump?
Did you hear the ignitor sparking?
Did you see if your circuit board is wet?
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Old 09-19-2021, 10:02 PM   #5
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I took off the outside cover and there was a little water in the exhaust tube. This was about 5 hours after the first incident. I started it again and it seemed to work ok until the fan turned off. The fan kept going at a low rpm like was getting a little juice.
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Old 09-21-2021, 12:54 PM   #6
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Originally Posted by waynetaylor55 View Post
I took off the outside cover and there was a little water in the exhaust tube. This was about 5 hours after the first incident. I started it again and it seemed to work ok until the fan turned off. The fan kept going at a low rpm like was getting a little juice.
Bugs, mud daubers, spiders get in the heater exhaust, work their way back inside nice and dark and build nests that disrupt airflow as referenced to the sail switch The 3 cycle and shutdown is by design. After the burner shuts off the fan will continue for a bit to cool the assembly down, that's normal. It may sound slower because the burner "jet engine" isn't going. I'd suggest a bug screen over the exhaust to keep critters out. Make sure you have propane in the tank by checking another appliance like the stove.
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Old 09-21-2021, 03:16 PM   #7
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Originally Posted by waynetaylor55 View Post
I took off the outside cover and there was a little water in the exhaust tube. This was about 5 hours after the first incident. I started it again and it seemed to work ok until the fan turned off. The fan kept going at a low rpm like was getting a little juice.
If your mh is more than a couple of years old the NUMBER 1 suspect is the circuit board

You can remove and try cleaning with contact cleaner, available at Walmart and all autosupply stores.
If that doesn't work the board is available here.
https://www.dinosaurelectronics.com/
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Old 09-21-2021, 03:34 PM   #8
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Isopropyl alcohol or rubbing alcohol is excellent, dries out any moisture, leaves no residue and is readily available. Does not hurt the electronics at all.


EDIT: I am referring to cleaning the circuit boards... Iso is very flammable, so use caution when cleaning items.
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Old 09-22-2021, 09:20 PM   #9
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Update

The next morning we tried the heater again and now it is working appropriately. We had run through a pretty intense storm in the north west the day before we started having problems. I figure that something got wet and now it is dried out.

Gotta love this stuff!
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Old 10-03-2021, 01:49 AM   #10
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Been there, done that.

Quote:
Originally Posted by waynetaylor55 View Post
This morning I turned on the heater and the fan came on, then the propane started. After about 15 seconds, the propane stops. Propane starts back up in about 0 seconds only to turn off again. Heater set to 80. (Inside is 60). Fan on auto.

This happens two or three times and the fan turns off. If I turn off the heater, the fan makes a weird noise and a slight amount of air comes out of the vents.

Did my thermostat take a dump?

My ACE 30.3 has the air intake at floor level under the fridge, it's just slats in the wood and I have a dog whose fur seems to find it's way in there.

First time I replaced the "fly switch" it worked, but after the second time I figured that the intake vent needed some sort of filter.

I took the wood slat vent cover off and stapled screening on the inside and have had no problem in over 2 years.

BTW, just take the "sail" switch out and blow it clean.
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Old 10-03-2021, 11:42 PM   #11
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Furnace

Iíve had to replace both the sail switch ( blowing it out with air didnít help but if you had take everything apart to get to it just replace it, and the board with a dinosaur unit, somehow the board didnít show any codes or lights of any kind new board showed air flow-sail switch.
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Old 10-03-2021, 11:57 PM   #12
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All of the above advice is great - clean the circuit board, get rid of critters in exhaust, double check propane flow....
Then you get to the point where the furnace "works"; but an expired (or poorly located) CO detector keeps you up all night opening windows/doors and fanning out your newly warmed air.

Seriously - don't take your propane/CO detector for granted. It could save your life. But they expire too - and gave us no end of grief the one and only time (so far) we truly needed our furnace.
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