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montreal · 09-06-2012, 12:06 PM

It's been a while since I've been here but elvis has been keeping us dry for about a month. He's been really well behaved to be honest.
I went away for 2 weeks and now the furnace will not switch on. It was working really well with no issues since we've had it.
I did have a water leak under the kitchen sink from outside so I think this may be the cause. I just checked some connectors that were on the floor and cleaned and dried them out.
The blower will not turn on and there is no sound from the furnace.
I have checked all the fuses at the convertor and have no problems. There is power at the thermostat (its the original simple one) and it's switching when the temp slider is moved on and off. There is also power at the wire connector on the side of the furnace.
Any ideas please as we froze last night.

D

Lumatic · 09-06-2012, 12:13 PM

You might need a new circuit board if your furnace has one, and if the existing circuit board is original. They are known to fail. A Dinosaur circuit board is a recommended reliable replacement

Aage · 09-06-2012, 12:24 PM

I wonder if the water might have caused a fuse to blow? IIRC, my old furnace had inline 12V fuse(s).

perryg114 · 09-06-2012, 01:11 PM

The fan should run when the thermostat is on. If it does not then you need to look at the fan relay. You can short the thermostat contact wires to make sure it is not there. If the relay is bad the fan won't run. If the fan won't stop the relay is welded together or the thermal switch is bad. I seem to remember a service manual floating around here.

Perry

Steve Bryant · 09-06-2012, 02:37 PM

montreal,
Perry has a good idea on the service manual. Take a look at this web page Service Documents. Scroll down to the furnace manuals and see if your model of Suburban is covered. Then download the appropriate manual for review.

These furnaces connect to the RV with four wires. Positive and negative for power and the thermostat wires that Perry is talking about. When the thermostat wires are shorted together (as if the thermostat switch is closed) the fan should at least run if the furnace has power and ground as previously mentioned.

Mike Leary · 09-06-2012, 02:39 PM

We have the same coach, I've had problems with the Suburbans, but never one like yours. I second the idea of shorting the thermostat wires together, first. Almost sounds like a fuse, in our 12-volt wiring panel, a RED wire runs the Stove fan, upper kitchen roof fan, light in bath and the Surburban. Check those. Let us know what you find. There is no way to service the Surburban without removal.

Aage · 09-06-2012, 03:44 PM

Quote:

Originally Posted by Aage

I wonder if the water might have caused a fuse to blow? IIRC, my old furnace had inline 12V fuse(s).

Quote:

Originally Posted by Mike Leary

Almost sounds like a fuse, in our 12-volt wiring panel, a RED wire runs the Stove fan, upper kitchen roof fan, light in bath and the Surburban.

Look for fuses. Look for fuses. First thing to check is always fuses when NOTHING happens.

Oh! Did you find the fuses? They are in-line, near the furnace, the typical white or black plastic spring-loaded type.

There's one for sure, and maybe two.

Unless of course, your furnace is completely different than mine...

ScrapIrony-2 · 09-07-2012, 09:43 AM

Our PO had removed the Suburban from under the kitchen sink, but left the vent holes filled with what I think used to be carpet. We adapted to the previous propane line under the sink, and attached an Olympia heater on a reinforced rubber hose(gas line), and it has served us well...the rear Suburban quit playing with me last winter, but we have a hand-portable Duraflame catalytic that works well, also. If it wasn't so much work to remove the rear Suburban, we would have more storage space, but the closet would have to be dismantled...I'd rather just carry the weight and camp somewhere...the catalytic heaters are excellent alternatives, cheaper to run than the Suburbans, won't drain a battery, and a slightly opened vent will assure you of...well...ventillation...we have onboard smoke/CO2/LP sensors just 'cause I'm kinda anal about that stuff, but they have kept us toasty in freezing weather...the heaters, not the...oh, never mind...there are other good heaters out there, but if you go to altitudes like we do(9,300+ ft), some of those heaters won't work in rarified air, so check the specs...a cover is a good idea, as catalytic panels are sensitive to dust, and unless you are duly diligent, a trash bag WILL melt on the heater, if not allowed to cool down. Nope, Haven't done that one...yet...but was well-advised by a friend who did...messy and expensive when you have to buy a new heater...BTW, don't forget to use the YELLOW thread tape for propane connections...m

Mike Leary · 09-08-2012, 09:31 AM

Quote:

Originally Posted by ScrapIrony-2

a cover is a good idea, as catalytic panels are sensitive to dust, and unless you are duly diligent, a trash bag WILL melt on the heater, if not allowed to cool down. Nope, Haven't done that one...yet...but was well-advised by a friend who did...messy and expensive when you have to buy a new heater...

I had one last year where a gal with a 40' bus conversion came over and said the coach was smelling of burning. I pulled the power and shut-off the propane. Smelled around the coach, could not find the source (I have a good nose for burning wire). I told her to get someone down to disconnect the batteries and call the Fire Dept. if that failed. As I was leaving the coach, I noticed a garbage bag that was melting; yup, hubbie had left the catalytic on and had covered it! Close call.

montreal · 09-11-2012, 05:53 PM

Thanks to all that suggested solutions. I checked the 4 wires going into the furnace. The two blue ones (from the thermostat) had voltage as did the red and yellow furnace power wires. I did not have any in-line fuses but traced the red wire up in to the fan above the 4 burner hob. I removed the filter and saw that the fan would not run as it was being blocked by old wasps nests!. It works fine now. Anyway...... I called a mobile RV tech that deals with American stuff. He pulled the internal parts of the furnace out and left the metal casing in place and tested on a bench in the van. The coiled wire in side the fan relay had come adrift. He re-soldered it and all is well. We also took the time to shake out more old nests (made of mud and dead cocoons) out of the exhaust and intakes. It works well and is a bit quieter now. very simple fix. If the fan wont run check the relay 1st. It is actually located where the vents are on the right hand side of the cabinet. We are going to cut a square in the side of the cabinet to expose the board, relay and switches for ease of maintenance next time. We will probabaly place a mesh cover over the hole stuck on with silicone or screwed down to protect it but and keep it ventilated.

perryg114 · 09-11-2012, 06:17 PM

Make sure the heat exchanger is not cracked or you could wakeup dead.

Perry

NorthernWind · 09-11-2012, 06:53 PM

First check the connectors, if water leaked into them they will corrode quickly and cause problems, they also can break or become brittle at the point of the connector or even just inside the casings at the connector.
This after all fuse have been checked but I just figured that horse was already Beeton. If you are sure the thermostat was working properly and the best way to check is just bypass it then it could be circuit board or even just a spider that moved into the burner nozzle! You would not believe what I find living and growing in furnace and hot water burners and also low voltage from old frayed lines.
Steve

Steve Bryant · 09-12-2012, 05:44 PM

Montreal,
It sounds like you had about the same problem that I (and others) have had in the past (see http://www.airforums.com/forums/f427...ace-86137.html). I'm glad you got things going again!

Regards,
Steve