Furnace shuts off after a minute

[drysz1]

When I turn on the thermostat setting to 70, the blower starts up and the furnace kicks on for just a minute before it cuts out (the blower remains on but obviously blows out cold air). The propane tank is full. Any ideas on why this is happening? We just bought the Motor Home a few months ago so this is our first time with temperatures down low enough to turn on the heater.

[Creativepart]

Sounds like it's not getting gas. Do the stove burners light? Will the fridge run on propane?

[asquared]

I agree, you may need to bleed the propane lines a bit. Turn off the propane valves, double check your connections. Turn back on the valves, then try to light the stove. After you are able to get good gas flow from the stove, turn it off and then try the heater again. It may take a couple of tries to get it going. Also, are you sure the cabin is colder than 70? You might try cranking the heat up a bit to say 75 or 80 until you get it running. Once you are sure it is running, you can drop it back to 70. Other explanation could be a pinched propane line, propane leak (I had a hole in a pinched propane line on a 1 month old fiver), or even a propane shut off valve flipped somewhere not obvious.

[drysz1]

Thank you for response. Getting good gas flow to the stove. Tried cranking up the heater to 85 and still behaved the same way. Appears the gas flow to the heater is the problem. The heater ignites then after 30 secs or so, extinguishes... then ignites again only to extinguish again. Then shuts down completely and only blows cold air.

I'll check the connections. Again, appreciate your response.

[Bama Rambler]

While it could be gas flow it could also be a failing flame detection circuit.

[clr]

If all of the gas connections and you have good gas flow to the furnace it could be the thermocouple has either been knocked out of alignment or gone bad. The thermocouple is the small tube looking device that is in the flame path at the front of the burner. The themocouple produces a small current when it is heated by the flame. The themocouple is connected to the main gas valve and is used to sense that the flame has lit. If out of alignment or bad the furnace will go through the start sequence and then shut off because it thinks the flame did not light.

[hotheadbilly]

This has happened to me on both my trailers my 2014 Dutch thenot on my 2016 Grey wolf 26DBH. What they found was ok both of them the flame sensor Rod is out of adjustment. It should be 1/8 of a inch away from the flame.

[dickhix1]

I had the same problem on a fiver. Stove worked fine, or so i thought, but heater would only run for a short time and then quit. After awhile it would relight and then shut down again. Problem was a defective regulator. Let enough flow for the stove burners but insufficient flow/pressure for the furnace. I did notice while checking for the problem, that the first stove burner i lit would go down slightly when i turned another on and down slightly more when i lit another. That's what led me to the regulator.

[TimVWulp]

Originally Posted by drysz1

When I turn on the thermostat setting to 70, the blower starts up and the furnace kicks on for just a minute before it cuts out (the blower remains on but obviously blows out cold air). The propane tank is full. Any ideas on why this is happening? We just bought the Motor Home a few months ago so this is our first time with temperatures down low enough to turn on the heater.

Hi I believe that the problem is a proof of ignition or flame. The electronic ignition system looks for a small mil volts that is passed through the flame to prove that the LP gas has ignited thermocouples are not used any more with the electronic systems. You may have a bad electronic ignition control board or the flame or gas is not in full contact with the ignition/flame rod causing a week signal through the flame sensor. The control board will make 3 attempts to light the burner and then lock out the furnace controls. This can be reset by tuning the furnace off and then back on. Spiders love to build nest around LP burners for some reason and can cause the electronics to short out through the webs.

Hope this helps Tim

[Grampa Jim]

Drysz1....There is a small rod at the flame that is called the flame sensor. There is a wire connected to it that goes back to the board. Take it off, clean it with a piece of steel wool and put it back together. That sensor can be coated with a small amount of soot that you can't even see and it'll interfere with the sensing message to the board. That is usually the problem that causes your described problem. I've been in the heating business for 40 years. I've seen it too many times. You'll correct the problem, more than likely, and say,,,,"Is that all it took???"

[poorbuthappy]

my acted the same way, bad house batteries. didn't make a difference when I was plugged into shore power or not. replaced the batteries, problem solved, heater worked fine.

[jeff64]

Originally Posted by Bama Rambler

While it could be gas flow it could also be a failing flame detection circuit.

X2 on the flame detection circuit.

Had an Atwood in a Jayco with similar symptoms. Changed board, no difference. Would light and go out. Changed igniter (and board) solved issue. Igniter sends feedback signal to board. But, what a royal PIA to fix. Had to remove kitchen sink and plumbing to get furnace out.

[Grampa Jim]

Jeff64,,,,In my 40 years of repairing furnaces,,,,I've never seen an ignitor such as the ones on RV's go bad. They just get coated with residue that interferes with the flame. Cleaning them with steel wool has always worked for me and my customers.