1996 36' U295 #4879 WTIB
You need to know I'm not technically minded or mechanically inclined.
The rear furnace comes on, but I remember it used to come on and you could hear it and feel it, but then what I assume is the blower would kick in and really heat the area up.
Comparing the front furnace to the back the force of output is markedly different.
Can anyone suggest what I should check/do? Is it okay to use it in this "limp" mode?
Not sure about your coach, but the front furnace in our coach is rated 15,000 BTUs and the rear furnace is rated 10,000 BTUs.
Look for a duct hose that has split or come off. In my 94 the furnace is under the floor of the rear most closet mirrored door.
Check the trouble shooting charts in manual.
http://techsupport.pdxrvwholesale.com/wp-content/uploads/2018/10/Atwood-Furnace-Master-Service-Manual-2007.pdf
Or even if someone has accidentally piled something on the ducting and collapsed it.
Our ducting is well covered with wood or other solid materials, so that I don't think I could put anything on any of the ducts by accident. My guess is that either the furnace isn't heating properly OR one or more ducts have failed. Replacing the furnace might be easier than finding and replacing the split duct. Neither will be cheap. Suggest you keep the work crew well supplied with donuts and coffee.
The front furnace is bigger then the rear as stated. I am not really sure you have a problem.
When the furnace starts the blower comes on blowing cold air. The burner then kicks on (you can hear it) and the air starts getting warm. Not as warm as the front unit. Then when it is done calling for heat the burner will shut down and the blower will keep on going. After the air temp has come down the blower will shut down. The air force (pressure) is less then the front
Agree. The furnaces are different sizes. I have the same coach. Does it blow hot ?
The furnace has only one blower motor. Heat exchanger fan and indoor circulation fan are on the same double shaft motor. Step outside while the unit is running and ensure the exhaust is blowing hot air at the access cover to the unit. If it's blowing hot outside and warm air inside then the unit should be working correctly unless it is "short cycling" due to not enough air movement. Your "sail switch" should prevent this but it could be stuck open. A failing motor bearing/bushing could be causing low fan speed but still enough air flow to satisfy the air flow safety switch.
It's very Difficult to trouble shoot remotely. 😎
Good luck, hope you are able to figure this out.
Check out this thread, I had similar issues. It has some good troubleshooting techniques and help. Mine ended up being a loose connection. Also when someone turns it on p, stand outside and listen. What do you hear? Also in that thread is a manual for the furnace that is very helpful with diagnosing. Report back.
Random Questions on Heating (https://www.foreforums.com/index.php?topic=43382.msg436459#msg436459)
Don't know if this would help, but here goes.
Our 1989 furnaces have reset buttons, accessible only on the outside. Open the furnace door and the reset button is up near top center.
Our furnaces were turning on but would cycle a bit then shut down. I hit the reset and the furnace ran like it should.
I think we are good. Thanks all! Sorry for delay. I guess I was expecting it sound like the main furnace. Y'all are wonderful though! It blows but not like the main furnace, but the sizing explains that! Appreciate you all! Happy Thanksgiving!