Furnace not working.

[Xqr]

We have a '14 voltage 3895 that were FT'ing in. Just got back from thxgvng and our furnace wont work. The blower comes on but the burner doesnt light. Lucky we have some electric heaters.
I took the panel off outside and the indicator light showed "air flow/ limit fault"
Is this something easy to fix?

 

[Xqr]

I tried resetting the thermostat, the blower, and the whole rigs electrical. Got a tank and a half of propane.

 

[Franktafl]

Look for something in the throat of the furnace where the gas flows. If dirt dobbers, they will be deep inside. Spiders love that location also.

 

[persistent]

Post make and model number of furnace for better advice.

Generally there are two air flow paths through the furnace. The first is the burner air intake and exhaust. The second is the cabin cold are intake and exit.

My furnace has a "sail switch" in the cabin air flow path. The switch must be "OFF" to start the cycle.
The switch must move to "ON" before the gas valve will open to allow gas into the burner.

If either air flow path is obstructed, the "sail switch" will not move to "ON". Gas valve will not open.

Clean both air flow paths. Clean the "sail switch" (they tend to accumulate dust layers).

Good advice posted above. Wasps, mice, and all manor of small creatures like to move in.

 

[Xqr]

Its an atwood 8940 - iii dclp. I went ahead and ordred a new sail and limit switch. From what i saw on YouTube the limit switch is going to b a pain to change.

 

[chrisski]

If you hear the burner trying to light with several clicks, but does not, then I would open the furnace up, pull out the “sparking unit.”

Shut the gas off first. Shut the switch off once you have the door open. Once the “sparking unit” is removed, reset the switch and see how it sparks.

The electrodes some times are loose or get too close and don’t spark right. They can be bent in shape. I put them 1/4” apart and a1/4” above the screen. When they spark, they it should spark between the electrodes to light. Too close and the spark goes to the screen and it won’t light.

 

[persistent]

The following site lists many Attwood manuals. None exactly match the model you posted. Do any of them look like what you have?

Atwood / Hyroflame Furnace – PDX RV

 

[KECoats]

You can buy a coiled spring tool about 12 inches long with a handle that can be pushed into the gas burner tubes to clear out spider webs, dead wasps and mud dobber nests. As mentioned above, those tubes need to be clear for the propane to flow normally. Both the furnace and water heater need to be clean. The little brush on the end of my tool wore out so I threaded a pipe cleaner into the spring to clear junk out. I have also since added a finer mesh screen to the vents on the access doors for these appliances to keep the critters out . Good luck!

 

[Rob P2]

MIne did the same thing. I pulled it out and replaced the thermosat and did the striker at the same time. Works great now.