Furnace - Air Flow Limit Fault

[Murr38]

Hi all.  I have a Atwood Hydro flame 7916-11 furnace in my Fleetwood Yuma (2005).

This past weekend camping up in the Rocky Mountains, it was getting pretty cool overnight!
The furnace worked like a charm on the first night - but had some problems on the second...(day and night)

The furnace was kicking on, and then doesn't fire up the burner, and then shuts itself off.
I was able to take off the cover, and see the fault light flashing the "Air Flow Limit Fault"
I am not sure where to start on this one.  I lit the stove top - to ensure the LP was working and there was no air in the lines...and it worked fine.

I am not sure how, (or if it just cooled off, and started working again) but I got it working again Saturday night.  I basically "rebooted" my trailer (like my computer guy says to do!) by pulling all the power, and starting it up again.

Does anyone know what this error indicates?  
Or where the Air Intake is for this furnace?  I wanted to check the Air intake to make sure it was clear - but I am not sure where it is.

I am running it again now out on the driveway to try to see if it happens again, but was hoping I might get some help!!

Thanks everyone, and happy camping!

[austinado16]

Go outside the camper and you'll find a stainless steel exhaust/intake port directly in line with where your furnace is locate.  Most of these furnaces preheat their intake air to make them more efficient, so they suck in fresh air from around the exhaust port.  

Examine the port closely with a flashlight, and you may elect to even shut the furnace off and blow through both ports with compressed air.  Bugs like to build nests inside the ports and this can really jack with your air flow.  RV places sell screens or covers to protect the ports during storage.

Or...you could have something mechanical going on with the furnace.

[mike4947]

You can find a service manual here: http://bryantrv.com/docs.html which should help.
What normally happens when the fan starts but the burner will not ignite is one of two things. Either air in the line which needs to be purged before the burner gts enough propane to ignite; it is normal for the propane in the lines to escape over time as the regultor is designed to do this when the cylinder valve is closed for long periods. Running a stove burner helps purge the lines.
Or the 12 volt voltage is low enough that the blower can't push enough air to activate the fan sail control. This makes sure the furnace has enough air flow to operate properly.

[PattieAM]

Your furnace requires 10.5-13.5 volts DC (battery) to operate the fan which will open the 'sail switch' allowing the propane to ignite.  You can read through the Atwood owners manual - //www.atwoodmobile.com for more information.

[Murr38]

Hi again.

Thank you for all the advice!
You are right, it was probably the battery getting low on juice.
I forgot to mention we were not plugged into power - this site had no power so we were running on battery alone!
It had plenty for the little lights but probably not enough for the furnace fan.

I am off to the store to get a multi-meter just to confirm...

Thanks again everyone!

Murr