Coachmen: Furnace won’t stay running Coachmen FE 195 rbs

[Tubbs805]

Great trailer, pre COVID build by 4 months, whew. No issues till now.
On our current trip we needed heater, just a little thankfully. But It won’t stay running.

Set thermostat to heat setting and temp high enough to come on. The fan starts but we never hear ignition from furness and then after 30 sec it just shuts off.

I’m thinking gas/pressure to furness only. Some sort of sensor fail? (stove and fridge both work fine on gas.)

Or most likely shutoff/reset feature ? If it has reset switch or feature where would you think to look.

Of course when back home will breakout manuals and do more research, as it’s the last morning of vacation camp.

Thanks in advance for all help and direction

[Skip426]

Furnace fan requires GOOD battery voltage to get to speed .

The fan triggers a sail switch , that's mounted in it's air flow ; low fan speed the sail switch won't activate and the control board shuts down .

If you're boondocking check your battery voltage , if you're on shore power , converter operation.

[Jon_C]

Originally Posted by Tubbs805

Great trailer, pre COVID build by 4 months, whew. No issues till now.
On our current trip we needed heater, just a little thankfully. But It won’t stay running.

Set thermostat to heat setting and temp high enough to come on. The fan starts but we never hear ignition from furness and then after 30 sec it just shuts off.

I’m thinking gas/pressure to furness only. Some sort of sensor fail? (stove and fridge both work fine on gas.)

Or most likely shutoff/reset feature ? If it has reset switch or feature where would you think to look.

Of course when back home will breakout manuals and do more research, as it’s the last morning of vacation camp.

Thanks in advance for all help and direction

If your stove works your gas is probably good. Fan runs so it’s getting power. First thing i do is wiggle all wiring connections most of the time this will work especially on a new unit. The other thing that could be causing issue is the sail switch. This switch has a “sail” attached to it that air pressure from the fan causes the switch to make, if this isn’t working it won’t turn on the gas for the burner. Possible obstruction keeping it from moving (wasp nest etc) or the wire connection to it not good.

[puttin]

The RV Geeks just posted this yesterday. You might not be able to perform some of these but at least you'll get an idea of what's wrong:


https://www.thervgeeks.com/rv-furnac...erm=2021-10-25

[Ljwt330]

Before you do anything, run a simple check.

Turn on the furnace and listen closely for a "tick, tick, tick..." of the igniter. Yes, the fan motor will be running but you need to get close enough to the burner to hear it.

You have gas service because your other gas devices work. You have 12v because the motor works. What you don't have is ignition.

A stuck sail switch will prevent 12v going to the gas valve and the spark igniter.

A bad control board will prevent the gas valve from opening and/or the igniter from sparking.

A bad gas valve solenoid will prevent gas from flowing.

A bad igniter will prevent gas from igniting.

All the above can explain your symptoms so the job is to eliminate suspects from the list. If you can determine if the igniter is sparking by listening for the "tick," that will either eliminate it from the list or move it to the top.


Of all the suspects listed, the igniter is the most likely, but don't jump to conclusions. Check and find out. Even if it proves to not spark, you will have to investigate the "why," but that's a bit down the road.

My suggestion is to determine if the igniter is working, report back, and move on from there. It will take you longer to read this post than to check for a sparking igniter.

[retnasaguy]

Bad sail switch

[Tubbs805]

Thanks for great advise.
This weekend we pull some access panels and explore the furness and figure it out. I dig learning this stuff and knowledge for next go around.

[retnasaguy]

Originally Posted by Tubbs805

Thanks for great advise.

This weekend we pull some access panels and explore the furness and figure it out. I dig learning this stuff and knowledge for next go around.

Any troubleshooting results?

[Tubbs805]

Fixed
Finally got time to pull furness out from under cabinet and oven. Took 30-45 min conservatively. Didn’t need to cut and splice electrical. long lead wire harness, so unit came out far enough to service.
Blew it out but not much was in there at 1 1/2 yrs old. Took out Sail switch and BINGO :thumb THE ACTUATOR or Sail was not even really sticking into air flow, flat against switch even in normally open position. Bent the actuator to have some air flow resistance and there ya go.
Returned air ducts remounted and it fired right up and started heating.

The bad! What was Coachman thinking not putting a access door for service or sliding shelf that pulls out with little prep.

The Good! I can now with confidence pull and reinstall my furness in 30-45 min.

Thanks for everyone who helped, may your karma points be strengthened.