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JohnJM's avatar
JohnJM
Explorer
Jan 12, 2014

Atwood 7920 Furnace

I have an atwood 7920 furnace in my lance slide in. It decided to not run at all on new years eve when it was 20 degrees outside. Even if I remove the thermostat and the wires are touched it will not come on. Reading the manual it says an internal circuit board failure is indicated by a steady LED indicator. IM not 100% sure what means, I cant find where the LED indicator is located. I do however have a steady red light on in the unit. I cant really see where it is exactly as I didn't take the heater apart.

Is that red light I see the indicator? If not what does it mean? Any ideas how to fix this?

I already replaced the wall thermostat. It was all corroded anyway and being finicky about turning the unit on.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Jan 13, 2014
    Just make sure the connector pins are straight and make good contact with the board.
  • JohnJM's avatar
    JohnJM
    Explorer
    Jan 13, 2014
    got the board ordered.....doesn't look to hard to put in.

    anything I should be careful of when I put it in?
  • JohnJM's avatar
    JohnJM
    Explorer
    Jan 12, 2014
    thanks guys. I figured the red light meant that.

    Power isn't an issue, I have it plugged in right now. The night it wouldn't run, we were boondocking but had a full charged batter. Whe I say wont run, I mean, no fan, no flame no nothing.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Jan 12, 2014
    RoyB wrote:
    Be sure your battery is up good if camping off the power grid. With just one battery we were good for one night running our trailer furnace heater. The blower draws a bunch of DC power from the battery.

    The other critical thing to check is the AIR VANE... This may be sticking on you.. Shuts furnace system off if the air vane is not held open with the blower running.

    Roy Ken


    AIR VANE.....that would be 'sail switch'
    Sail Switch problem is 1 flash every 3 seconds of LED on circuit board.

    OP's furnace doesn't run....no blower, no nothing
    OP has a steady ON RED LED........board internal fault. New board.
  • RoyB's avatar
    RoyB
    Explorer II
    Jan 12, 2014
    Be sure your battery is up good if camping off the power grid. With just one battery we were good for one night running our trailer furnace heater. The blower draws a bunch of DC power from the battery.

    The other critical thing to check is the AIR VANE... This may be sticking on you.. Shuts furnace system off if the air vane is not held open with the blower running.

    Roy Ken
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Jan 12, 2014
    The LED indicating light is on the circuit board of the furnace.

    These are the error codes:
    Internal Circuit Board Failure...........Steady on, no flashing
    Limit switch/Airflow problems............1 flash with 3-second pause
    Flame Sense Fault........................2 flashes with 3-second pause
    Ignition Lockout Fault...................3 flashes with 3-second pause


    Steady ON Red LED.......your circuit board is bad.

    Get a new from Dinosaur Electronics. Direct replacement/high quality boards........LINK

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