Furnace Issue

[Dragonfly72]

I have a 2000 Crossroads Prep series.
The furnace is not working properly. It turns on, ignites and blows heat for about 30 seconds and then blows cold air until it cools off and shuts down.
We replaced the thermostat and that didn’t help.
Any help is appreciated.
We have a book for everything except the furnace

 

[Lloyd S]

So what is a (prep) series? I can't say I've ever heard of that one.

Here are a couple links that might help you.
https://www.crossroadsowners.com/forums/f54/2022-volante-34re-furnance-wont-turn-on-17202.html
https://www.crossroadsowners.com/forums/f25/2015-crossroad-reserve-heating-problem-17263.html

 

[mark5w]

Found this Lloyd.

https://www.rv.com/archive/rv-model-news-crossroads-rvs-prep-series/

 

[Wingerdinger]

If you are interested in troubleshooting the furnace yourself, there are two manufacturers of furnaces for RVs, Atwood, which is now Dometic, and Suburban. Open the vent access panel and find the model of the furnace.
Then go to the manufactures website, and find the service manual, not the owners manual.
They have good troubleshooting in the manual.
There are also a bunch of YouTube videos on the subject.

 

[Dan Erikson]

Sounds like the thermocouple aka flame sensor. Heats up opens up and makes the control board think the flame blew out and shuts down the gas. Or it never sends a flame signal to the board and it drops out do to no flame. Either way you'll have to do exactly what has previously been suggested. Make, model, service manual, Trouble shooting guide and parts list. If it's what I think it is, it should be a reasonably easy fix. Maybe a sail switch as well thinking the blow didn't turn on.
Check this link out.

https://homearoam.com/how-to/rv-furnace-troubleshooting