Atwood furnace - clunking noise after shutting off

[mermald]

I have an Atwood furnace in my unit which is a 2019 Keystone Cougar and the furnace will run and once the temperature is right, it shuts off the heat and then the fan runs for a period of time. After the fan shuts off, within 15 seconds I hear a relatively loud clunking noise. Is this normal?

I was searching online and all I have been able to find is information about normal household furnaces and when that happens it's due to a filter needing to be cleaned. From my understanding, which is limited, the furnaces in an RV don't have a filter, so I am not sure what is causing the noise.

Any information would be greatly appreciated.

[Old-Biscuit]

Sounds like a loose air or combustion wheel
Motor is dual shaft with room air wheel on one shaft and combustion air wheel on other side shaft

Both held on shaft via hex screw...if loose wheel could clunk as fan winds down

Nothing else is rotating in furnace

[mermald]

Originally Posted by Old-Biscuit

Sounds like a loose air or combustion wheel
Motor is dual shaft with room air wheel on one shaft and combustion air wheel on other side shaft

Both held on shaft via hex screw...if loose wheel could clunk as fan winds down

Nothing else is rotating in furnace

How difficult is that to fix?

[Old-Biscuit]

Remove exterior access panel
Remove cover over motor to expose air wheel
Long-handled Allen Wrenches (9/64" and 1/8" for the air wheel and the combustion wheel)


What is the Model Number?
AFM, 85/89 etc

[mermald]

Originally Posted by Old-Biscuit

Remove exterior access panel
Remove cover over motor to expose air wheel
Long-handled Allen Wrenches (9/64" and 1/8" for the air wheel and the combustion wheel)


What is the Model Number?
AFM, 85/89 etc

DFMD36131 is what is listed on the unit

[Old-Biscuit]

DFM35131......
Dometic Furnace
Medium size
35K btu rated
131....Denotes fuel/access/valve type
**Documentation uses AF (Atwood Furnace....Dometic acquired Atwood)

Here is an installation manual ....EXPLODED View on pg 9
http://techsupport.pdxrvwholesale.co...m-Furnaces.pdf

[mermald]

Originally Posted by Old-Biscuit

DFM35131......
Dometic Furnace
Medium size
35K btu rated
131....Denotes fuel/access/valve type
**Documentation uses AF (Atwood Furnace....Dometic acquired Atwood)

Here is an installation manual ....EXPLODED View on pg 9
http://techsupport.pdxrvwholesale.co...m-Furnaces.pdf

Looks like I may need to call a professional....