Furnace blowing warm then cold air

[Cbwilki]

I have a 98' Jayco tent trailer, our first trip out this spring the heater blew warm air for about five mins or so then cold air the rest of the night. That same weekend we blew the gfci and lost all electricity. We replaced the gfci but we still don't have heat.
We fond the circuit breaker and everything looks good.
Its like its not getting enough heat, you can hear the propane click on at first it lasts anywhere from 3-10 mins, then it blows cold air. If you leave it alone it will continually blow cold air. If you move the thermostat back down to cold then up to heat again. The whole process starts over or it just blows cold air. I should also note, the hot water works well as does the propane stove.
This year the heater has never gotten the whole trailer up to the setting on the thermostat.
Do we need a new furnace? Is that something we can do ourselves? Right now we're using two ceramic heaters which work really well when were hooked up, but we were dry camping last weekend and it was really cold!
Thanks in advance!

[Herk7769]

I assume the furnace is as old as the trailer.

There could be many reasons for your symptoms.

The attached troubleshooting guide will help you eliminate the "easy fixes" and will confirm a "hard fix" so you can call a service center.

Changing one out is not "impossible" but it might be beyond the average RV backyard mechanic.

[Md Jeff]

I had a 2003 Jayco that would do the same exact thing, heat for a bit and then blow cold, I would shut it off and sometimes it would heat again and sometimes it wouldn't; ended up replacing the control board on the furnace, about $80 and a hrs worth of time. Hope it helps.

[vortecmax 8311ss]

sounds like the pilot light is not lighting if theres no pilot light to light the burner in the funace theres not going to be heat try cleaning area around pilot with some compressed air and a light scrub with an old toothbrush and see if that works

[Oakman]

You might try asking this on the Jayco Owners Forum. There might be more people who are familiar with that year of tent trailer.