Discovery: Rear Furnace

[widge]

On my 2004 Fleetwood Discovery, the rear furnace is not lighting.The motor starts the solenoid clicks I smell a little propane,it will do it 3 times and time out,I can't figure out to access the furnace.There is an access panel where the motor and control board is and the red LED is flashing 3 times on the board.Anybody experience this or have solutions?

[foundwaldo]

What model furnace do you have? Mine does the same thing. After several attempts it worked this weekend. I am suspecting it is the electrode on mine. Usually does it after rain to me.

[OneOrbit]

I'm currently having the same issue, however, I am able to get it to work with some effort. This took a lot of experimentation.

To get it to work.
1. Turn zone 1 & 2 heaters off and then turn off heater.
2. Turn off anything else that uses propane.
3. Shut off all power to coach (Salesman Switch)
4. Disconnect Propane from the source.
5. Wait at least 5 min
6. Connect Propane to the source
7. Turn on the power (Salesman Switch)
8. Turn Heater to On
9. Select Zone 2 and only turn that zone on and set to higher than the current temperature.
10. If that works turn on anything else that currently needs propane.

The propane needs to work it's way back to zone 2 area. if the heater tries a few times and doesn't work. then switch the heater off for a couple of minutes and then switch it back on.
If 3 tries doesn't work then...

1. Turn off zone 2
2. Turn on Zone 1 and set to a higher than the current temperature.
3. Let zone one run for at least 15min
4. Turn on Zone 2 and set to a higher than the current temperature.
5. If that works turn on anything else that currently needs propane.

I'm thinking that my regulator is bad since my heater works, but seems to not be getting enough propane at times., and will be getting a new one asap.

Once the above actions get zone 2 going again, it runs well for as long as I have propane. Once I run out or need to refill I am having to go through this procedure again.

I hope this helps

[foundwaldo]

Mine is definitely not the propane everything else works, as well as I smell the propane, and I hear it light but then it shuts itself off like it does since the heat.

[discovery39s]

Here is the possible issue that I have experienced. Pull the board and inspect to see if there is a white haze on the back of the control board. This haze was moisture that dried to create enough impedance across the components. Using a tooth brush, vigorously scrub the back of the board, non-component side until clean.

39S models have had bedroom sinks that would condensate feed lines or leaks from the drain or feed lines. This drips down the feed lines, through the floor and drips on top of the control board of the rear furnace.

Hope this helps!

[completelymo]

Originally Posted by discovery39s

Here is the possible issue that I have experienced. Pull the board and inspect to see if there is a white haze on the back of the control board. This haze was moisture that dried to create enough impedance across the components. Using a tooth brush, vigorously scrub the back of the board, non-component side until clean.

39S models have had bedroom sinks that would condensate feed lines or leaks from the drain or feed lines. This drips down the feed lines, through the floor and drips on top of the control board of the rear furnace.

Hope this helps!

This is most likely your issue. I had the same thing happen twice than I finally eliminated the moisture issue and all is good.

[OneOrbit]

Originally Posted by completelymo

This is most likely your issue. I had the same thing happen twice than I finally eliminated the moisture issue and all is good.

Thank You!
Do you know where the board is? How I might find it?

Thanks
John

[Al n Cindy]

Moisture and electronics don't play nice; it is not uncommon for boards to go bad. I agree with 39S that is probably the problem; it is the most common and the easiest to check. Other issues could be insect nests and sail switches.

If cleaning/drying out the circuit board doesn't work, try switching the circuit boards between front & rear furnaces. This is the easiest way to tell whether your circuit board is the problem. If it is, replace it with a Dinosaur board--superior to the OEM--they run about $100:


Location of the board is one of the problems. On many rigs, they put it on the floor of the furnace compartment where it can collect water! Mine are both mounted on the side:


The board snaps off/onto the plastic frame:


When we lost one board I used the good one to heat the bedroom during the night and moved it to the front during the day till I received the new board from Amazon (or perhaps it was PPL in Houston).

[mike toon]

My furnace would start but shut down with the same blinking as yours.
I removed the electrode and cleaned it with scotch brite.That fixed the issue.Start with the easy stuff.

[discovery39s]

I neglected to mention. I applied clear silicone to the back side of the board after cleaning. Provides a layer of protection so moisture cannot accumulate directly on the solder tracks. The better U.S. built boards have a clear coat on them that does the same thing.
Safe Travels

[widge]

Do you have to take off the gas valve to remove the electrode?

[widge]

I tried all the above with no success,I'll try the electrode next.
Thanks for all the information to all who contributed.

[mike toon]

I got the electrode out without removing the gas valve.I used 1/4 extension and a universal.When going back in, I taped the screw to the socket to hold it into place.
Cleaned the first furnace electrode the same way.

[widge]

Thanks that should make it a little easier,hopefully it works.