Atwood AFMD35131 furnace - LED on board flashes w/o pause

[Jay Merritt]

2016 Montana 3611 Legacy

Atwood AFMD35131 furnace does not make any sounds.

The LED error light on the control board flashes without pausing.

The flash codes do not cover this flash pattern.


Where do I start?

[Foldbak]

Originally Posted by Jay Merritt

2016 Montana 3611 Legacy

Atwood AFMD35131 furnace does not make any sounds.

The LED error light on the control board flashes without pausing.

The flash codes do not cover this flash pattern.


Where do I start?

AI Overview
A continuous flashing light on an Atwood AFMD35131 furnace typically indicates a flame sensing issue, meaning the furnace is not detecting a proper flame during ignition, causing it to repeatedly try to ignite and then shut off due to safety concerns. Potential causes for this flashing light:

• Dirty flame sensor: The most common culprit, a dirty or contaminated flame sensor can't accurately detect the flame, causing the furnace to cycle on and off.

Damaged flame sensor: A physically damaged flame sensor might not be able to function properly.
Improper flame sensor alignment: If the flame sensor is not positioned correctly, it might not be able to pick up the flame signal.
Low battery voltage: A low battery can sometimes affect the furnace's ability to properly ignite and sense the flame.
Clogged burner nozzle: A clogged burner can cause an inconsistent flame, leading to flame sensing problems.
Airflow issues: Insufficient airflow through the furnace can impact flame detection.

• What to do:Clean the flame sensor: This is usually the first step. Access the flame sensor, carefully clean it with a fine sandpaper or a soft cloth, and then re-install it.

Check for damage: Inspect the flame sensor for any visible signs of damage and replace it if necessary.
Check sensor alignment: Ensure the flame sensor is properly positioned in the burner area.
Check battery voltage: If applicable, check the battery voltage and replace if necessary.
Clean burner nozzle: If the burner nozzle is visibly dirty, clean it to ensure proper fuel flow.
Check for airflow obstructions: Make sure the air vents are not blocked and the furnace is not located in a restricted space.

• If cleaning and checking the flame sensor doesn't resolve the issue, it's recommended to contact a qualified RV technician to diagnose and repair the problem.

[Jay Merritt]

Thanks, but AI is wrong

1 flash= low voltage
2 flashes=ignition failure. <------ xxx
3 flashes=open high limit
4 flashes=stuck APS
5 flashes=module fault


In my case the fan motor must start first, then the sail switch must be triggered, before ignition is attempted.

There are no sounds or movement of the fan motor

[Daryles]

There is a furnace manual in the files section.
If the blower is not coming on, looks like you are at step 1 in the flow chart.
Check your voltage at the control board.
I would start by changing out the black 15A self resetting fuse with a regular blue 15A fuse. Simple test. The black self resetting fuse has been notoriously problematic.

[Jay Merritt]

Thanks,
There's a regular fuse in the fuse box
There is power to the board because the error LED lights blink. On shore power with 1200 AH of lithium batteries fully charged.
I am going to test the specific power points on the board when it warms up a bit.
I will also apply 12v to the motor to see if it turns.

I was hoping someone would recognize the LED flash pattern

[Jay Merritt]

Update: the standard 15a fuse in the fuse box was blown, even though the LED in the fuse box was not lit. I replaced it with another, and it blew, but this time the fan motor ran for a second or two.

[Jay Merritt]

Final update: I put 12v directly to the motor.* It sputtered a bit like there was crud up there.* I let it run until the RPMs leveled off.
I replaced the fuse with an automatic breaker (slow*blow)*
I plugged the control board back in and it fired up without blowing the fuse.

[Foldbak]

Well AI isn't all that..........yet