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bhsl8 · 10-10-2005, 01:20 PM

Hi all, been a while. No camping for over a year due to circumstances in someone else's control. Just fired up the heater three days ago as I intend to live a good portion of the autumn and perhaps some of the Wisconsin winter in the AS.

All systems were go until about 4 AM today. I know I am low on gas but my stove still works and the pilot light stays lit on the furnace. The problem is that when the thermostat calls for heat the fan runs but no combustion to make me warm.

I realize this my be a repeat question from some time back and would settle for a reference to look up. Thanks in advance.

john hd · 10-10-2005, 01:31 PM

brouck

long time since you were on last, good to see you posting again.

how is the condition of your batteries? if the 12 volt source is low the fan in the furnace cannot build enough speed to trip the sail switch, that is what switches the gas valve.

good luck!

john

bhsl8 · 10-10-2005, 02:05 PM

Thanks John, it is good to be back. Life has changed dramaticly, for the good I feel but I am still finding my sea legs. Moving on...

The problem is present with shore power. I have not tried it with just the battery. Is it possible that a certain fuel pressure is required and the problem would resolve with topping off the fuel?

john hd · 10-10-2005, 02:11 PM

filling the tanks and going from there would be a good place to start.

john

Kinder · 10-10-2005, 02:19 PM

This is the same problem I am encountering. The fan + thermostat work but the furnace does not stay lit. It worked for about 10 days, but recently has quit. I have been calling around but nobody will look at my furnace because it is too old or because they don't work on RV furnaces. I don't have a TV so I can't bring my Airstream to any dealer. I have to get it fixed, or else go through winter with just electric heat.

I'll check to see how much gas remains in my tanks, though I should have plenty. My next step was to follow the service manual and take out and thoroughly clean the furnace. Any reason it would konk out simply due to too much dust and junk inside? I'm fairly handy but have shied away from messing around with anything that had a gas line in the past... but looks like I have to tackle this one.

bhsl8 · 10-10-2005, 02:19 PM

So, that is not an illogical plan then eh? Thanks

bhsl8 · 10-10-2005, 02:27 PM

So Herr Kinder, please keep me posted with your investigations and I will do the same. I am short of time till weeks end and it is already in the 20s at night. Life is good!

Pick · 10-10-2005, 04:29 PM

If the pilot stays lit, and the fan comes on, it could be several things, either the sail switch is broken,(or the sail itself broke off the switch) or the gas valve is not working. The inside of the plenum could have rusted, if the trailer sat for a year, rust could have piled up and covered the burner. If the furnace is the original, you may have to spring for a new unit. I do not think the gas valves are available for older Suburban furnaces any more, and if the plenum is rusted, you risk a leak and carbon monoxide poisioning.

bhsl8 · 10-10-2005, 05:09 PM

Thanks for the input. If indeed it is, as you postulate and I fear, that the unit be replaced, what kind of options are out there lurking that range from the sublime to the ridiculous?

Thanks again.

bhsl8 · 10-11-2005, 10:30 AM

Update.

I more closely examined the Suburban furnace and it is not really rusty. In fact, it looks to be in very good condition. While I was investigating, the lights in the trailer began to dim. This obviously should not happen if I'm on shore power.

I decided to look at the power source and the recepticle does not allow the adapter from the power line to fully seat and hence, no shore power. I took it apart and rigged it up temporarily and bingo, shore power and enough juice to trip the sail valve. Thank you John!

Now all I have to do is replace the antiquated recepticle with a modern GFI and I'll be in business. It is leased property so I guess I should ask the owner but it seems he would be pleased.

I know my AS is equipped with 30 amp service. The circuit is 15 amp. Is that sufficient to run the fan and sail valve? I don't anticipate doing much but sleeping in the trailer.

Thanks again for everyones help and suggestions.

Kinder · 10-11-2005, 01:42 PM

Well, I feel a bit sheepish, but the furnace problem was quite easily fixed. I started over, beginning with the LP cylinders and gas lines, and found a leak had developed from my second tank which I switched over to shortly before my problems started. To be exact, the short pigtail line from the cylinder to the regulator was not tightly attached to the regulator.

Got down to 36 last night, so I was able to get some real-life testing done, and the furnace works great once again. Next step is to get a 120 gal tank from Amerigas so I don't have to fill up my tanks every few weeks. LP runs $2.23/gal in Reno... ouch! Last year I was paying $1.4x in Minnesota, course that was a 500 gal tank...

Good luck solving your problem, bhsl8--may your solution be as simple and cheap as mine.

john hd · 10-11-2005, 05:43 PM

Quote:

I know my AS is equipped with 30 amp service. The circuit is 15 amp. Is that sufficient to run the fan and sail valve? I don't anticipate doing much but sleeping in the trailer.

yes brouck that will do just fine.

glad you found the problem, does your trailer have some kind of indicator light so you know it is plugged in properly?

mine has a bright red l.e.d. above the stove.

john

niss1679 · 10-11-2005, 07:09 PM

Hey all,
I havent been posting lately. Ive had my 68 Safari 23' Twins for a little over a month. Ive been spending every minute after work and on weekends restoring her. Ive completely gutted her and now have her almost in usable condition. I am taking her (and my wife) to Delaware National Seashore the last weekend of this month. Ive read all the recent posts on furnace problems but still have a question. I can light the pilot and it stays lit. When I turn up the thermostat I hear something click. I do not hear a fan running and Im hooked up to shore power now. I saw talk of a recepticle, I didnt see one in mine, Ill have to look closer. Do I have to take the unit out, or just the front cover off? The furnace is an original Suburban and is in very good condition. Can anyone give me a direction or something to look for? I know that I owe alot of pictures of the restoration, I'll get them taken and posted soon.

Thanks, Scott
68 Safari

bhsl8 · 10-12-2005, 01:37 PM

First, this response is for John. There is a white indicator light street side near the rear of the coach that is supposed to tell me if I am on shore power... I think. It has never worked that I know of in the three years + that I have owned the trailer. That side of the trailer now faces the woods on the lot where it is parked so I would probably never have noticed anyway.

Now for Scott... the receptacle to which I referred is on a garage and the source of the shore power which I was not accessing. There was nothing amiss on the trailer. If I can piggyback on John's earlier suggestion, maybe the sail valve is not opening and hence not supplying gas to the burner.
Please John, jump right in here before I am over my head.

Chuck · 10-12-2005, 02:07 PM

Quote:

Originally Posted by bhsl8

There is a white indicator light street side near the rear of the coach that is supposed to tell me if I am on shore power... I think. It has never worked that I know of in the three years + that I have owned the trailer.

That is most likely a polarity indicator light, which should only light if there is a polarity problem. (mis-wired receptacle). So the fact that you've never seen it lit is a good thing....

If I recall correctly, the "shore power indicator" light is in the control panel in my '73, and the bulb was blown out and never replaced.

bhsl8 · 10-12-2005, 02:25 PM

Thanks Chuck. I should get out my manual again and review. Remeber when you first got your manual and the AS was new to you? We just couldn't get enough info. As time went on I got cocky and dove in without looking. God, I was young and foolish. Now I'm old and foolish!

john hd · 10-12-2005, 06:00 PM

Quote:

If I can piggyback on John's earlier suggestion, maybe the sail valve is not opening and hence not supplying gas to the burner.
Please John, jump right in here before I am over my head.

no you are doing just fine.

john

niss1679 · 10-12-2005, 06:38 PM

Now for Scott... the receptacle to which I referred is on a garage and the source of the shore power which I was not accessing. There was nothing amiss on the trailer. If I can piggyback on John's earlier suggestion, maybe the sail valve is not opening and hence not supplying gas to the burner.
Please John, jump right in here before I am over my head.[/quote]

Thanks Brouck,

Would I be able to keep my pilot light lit if the sail valve is defective? If I take the front cover off the unit will I be able to seeit or will I have to pull the unit out?

Thanks, Scott
68 Safari

bhsl8 · 10-13-2005, 08:25 AM

Yes, the pilot light may stay lighted in spite of a sail valve failure, if my experience is an indicator. One difference between your situation and mine was that the fan did run when the thermostat called for heat. There was enough juice in the battery to run the fan but not to trip the sail valve.

It sounds to me as if you are getting no power to the furnace and the burning of the pilot light is not an electrical issue. Maybe it makes more sense to run down that problem before opening up the furnace.

Darol Ingalls · 10-13-2005, 09:54 AM

If you have to resort to removing the furnace "works" to fix the problem, it's a good idea to check the main gas orifice to the heat chamber. Unfortunately, you have to disassemble more of the unit to get to it. There is a square plate on the rear of the heat chamber attatched with four screws and the gas line (steel) is welded in the center. Remove the plate and gas line being very careful of the gasket. The brass orifice is screwed on the end of the gas line. The culprit is usually spiders. They enter through the exhaust port and seek out the oder of the gas. Even the smallest particle of dust or spider web can block enough of the gas flow to prevent furnace operation. This is time-consuming and frustrating work since most of the screws are usually rusted, but compared to buying a new circuit board, gas valve, etc. it's a cheap fix if it results in heat! Darol