Suburban Furnace Issues

JEagan · 04-27-2021, 05:40 PM

I have a 2006 Itasca Sundancer 430V and just started having an issue with our furnace not working. The furnace is a Suburban Model # SF-30 2321J Serial # 054908950 and was working fine up until two days ago. My biggest question is:

On this model of RV, can I get access to the furnace to start trouble shooting from in the cabin area OR is access only from the outside where the intake/exhaust ports are?

It looks to me like access is only from the outside hinged panel just to the front of the propane access panel but I just want to make sure before I get underneath to free up the rusted screws

All other gas appliances are working fine, luckily we have a The Coleman ac with heat pump so we are getting by but some nights get down into the upper 20's and the heat pump will not work at that temp.

The thermostat will start the furnace blower and I hear three attempts from the ignitor but the unit does not start heating and ultimately the blower shuts off several minutes after the last attempt

Any troubleshooting advice would be greatly appreciated related to this model. I am aware of the online videos but most are not model specific but I am confident in being able to track down the problem

Phil G. · 04-28-2021, 01:43 PM

Quote:

Originally Posted by JEagan

I have a 2006 Itasca Sundancer 430V and just started having an issue with our furnace not working. The furnace is a Suburban Model # SF-30 2321J Serial # 054908950 and was working fine up until two days ago. My biggest question is:

On this model of RV, can I get access to the furnace to start trouble shooting from in the cabin area OR is access only from the outside where the intake/exhaust ports are?

It looks to me like access is only from the outside hinged panel just to the front of the propane access panel but I just want to make sure before I get underneath to free up the rusted screws

All other gas appliances are working fine, luckily we have a The Coleman ac with heat pump so we are getting by but some nights get down into the upper 20's and the heat pump will not work at that temp.

The thermostat will start the furnace blower and I hear three attempts from the ignitor but the unit does not start heating and ultimately the blower shuts off several minutes after the last attempt

Any troubleshooting advice would be greatly appreciated related to this model. I am aware of the online videos but most are not model specific but I am confident in being able to track down the problem

You say you have an AC with heat pump, but that some nights are too cold for it to operate in heat mode. This means that you are talking about camping on hookups or drycamping with the generator running. Under these conditions with a furnace that's not working ... why can't you just use one or two portable electric heaters inside the coach? We always carrying one of these along, just in case.

JEagan · 04-29-2021, 08:22 AM

Thanks for the advice Phil, I did pick one up and am using it in the interim until I get the furnace fixed

Morich · 04-29-2021, 08:55 AM

When looking at a new issue, I like to go direct as possible to really reliable info, so look online for the closest thing to info from the builders.
We often get into things being just a slight bit difference from year to year, model to model and it can really get us confused if things are just that tiny bit different.

So looking for info to assist, I came across this manual that seems what you might need as it covers one of your first questions!!!
Page six is "furnace removal" and 30/31 are troubleshooting!

https://manuals.heartlandowners.org/...11-05-2015.pdf

See if that is a good place to start?

Morich · 04-29-2021, 09:06 AM

IF you are able to access the controls and IF this is the correct manual, it sounds like you might be near this point on the flow chart? I love flow charts as they keep me from having to think so hard looking at wiring, etc for how it works!

Click this drawing snip to get a better view?

JEagan · 04-29-2021, 09:46 AM

Richard, thank you so much for sending that to me, it will be invaluable moving forward. That is a very comprehensive manual

I am also a huge fan of flow charts, they make life much easier

I haven't looked yet but does that particular site have other service/repair manuals?

imnprsd · 04-29-2021, 09:49 AM

OP: If you post some Suburban symptoms then others may be able to point you in the right direction.

* Are you trying to say nothing works when you turn the heater on?

Here's a few things I keep in my Suburban repair folder that may help you and others:

https://www.doityourselfrv.com/rv-furnace-repair/

https://www.youtube.com/watch?v=lJXT...DJyKF&index=15

What this forum and others lacks is a lot of information on Surburban repairs, but I came across the video above and the picture below suggest one such quick fix was an an "open" circuit caused by a bad connector or bad installation.

If you are not getting any calls from the Thermostat, and you know you have power to the suburban, but nothing happens, then you may have an open caused by a connector or maybe your circuit board is bad. IDK.

Does anyone know a work around to buy pass the circuit board? ...Or is there a circuit board "cold solder" joint that can be repaired?

Morich · 04-29-2021, 01:21 PM

Quote:

Originally Posted by JEagan

Richard, thank you so much for sending that to me, it will be invaluable moving forward. That is a very comprehensive manual

I am also a huge fan of flow charts, they make life much easier

I haven't looked yet but does that particular site have other service/repair manuals?

When looking for manuals, I just go with the name and model number looking for manuals. It often brings up lots of trash sites that refer you to forums and places where they want to sell manuals and I skip over those as too unreliable to really spend a lot of time on if I can look further down the list to find somebody like Suburban, etc. which is closer to the source for good info.

The tricky part is finding the model that matches what I have as so many different makes and models of furnace, stove or frig may have those slight different features that lead us off into the bushes.

If I can find the exploded drawing to ID the parts, a wiring diagram and then a troubleshooting guide or flowchart, I find it cuts out a lot of the waste time.
After we have repaired a few cases, we tend to think of things like a furnace as all the same but that leaves us prone to missing some small point like a single wire that is loose and we can wind up replacing a very expensive part and thinking we did good because the whole thing works when we get done but if we had done the real down and dirty looking we might have found it just a loose wire!

The difference in being a parts changer versus a tech!!

JEagan · 04-29-2021, 01:37 PM

Thank you for the information and advice, here is a listing of current furnace conditions:

When I manually turn the thermostat to gas heat, the thermostat will start the furnace blower and I hear three attempts from the ignitor but the unit does not start heating and ultimately the blower shuts off about 3 minutes minutes after the last attempt like it is supposed to

After turning the unit on, if I go outside and smell for gas, I can hear the ignitor and smell gas during each of the three attempts

The system logic is designed such that if I am using the electric heat setting on the Coleman, and it gets below 36 degrees the unit cannot provide heat and the Suburban should automatically come on to provide supplemental heat - It is not doing this either I suspect because the gas never gets ignited

I do have a few comments and questions for you 1) I have seen the video you sent - great example of good trouble shooting process 2) Are the parts that you listed specific to the Suburban Model # SF-30 2321J that I have?
3) Do you know where I can get the parts break down for the unit?

Thanks again for your help :-)

Morich · 04-29-2021, 03:21 PM

If you can hear the "snap" of the igniter and smell gas, things get down to the small points as those are the two main things it takes to light!
So the next step is to make sure the snap is actually the igniter, not some stray short sparking in some other location but that would be odd. But assuming the spark you are hearing is at the same point hte gas is entering, ignition is expected, so you will need to check that the igniter has not slipped or bent out of the correct spot to meet the gas.
Maybe a loose adjustment or bent or simply the end is burned off too much. Something that you may be able to see if you can get into have a look.

This is something that may seem backward if used to dealing with the home furnace where the fire is lit and then the blower comes on but in the RV, they don't want to risk filling it with gas, so they start the blower, make sure the is good airflow and THEN as a final step, they light the fire.

But it sounds like you are getting most of the complex part done but the igniter is not at the same point as the gas! Careful here! There is some hazard if you are too close and very much gas is setting there and suddenly lights off, it can burn off the eyebrows! Just try to stand back from any sudden lighting while watching for the igniter sparking. You may look in and find the danged thing has come loose and is laying down in some obvious wrong spot???? We should be so lucky!

JEagan · 04-29-2021, 07:28 PM

Richard, you bring up some great thoughts on the igniter - it wouldn't surprise me with a 15 year old furnace if the igniter was burned back and out of spec, I have also read about carbon tracking that redirects the spark from the appropriate ground for a good spark

There are several other concerns I have - could be a bad thermal limiter switch that would not be letting the spark go correctly but I would think a bad switch would kill the spark altogether and I shouldn't hear any "snapping"

Another concern is incorrect air to fuel ratio in which case the spark could be happening but cannot ignite the gas - I am not sure what the potential causes of this may be but it seems like a possibility

Finally it could be just a bad logic board on the unit - not sure right now how to determine that either

I appreciate all your input thanx!!!!

imnprsd · 04-30-2021, 12:10 AM

I have never fixed my Suburban. That said, shouldn't you first confirm your sail switch is good or bad? (See comments from other owners below.)

Question: Is this think N.O. or N.C.?

WHAT DOES THAT FLOW CHART SUGGEST IS THE PROBLEM?

===

Here's some more reference material"

https://www.youtube.com/watch?v=-g3_Y7MqChE

https://www.rvupgradestore.com/Sail-...-p/41-1318.htm
The sail switch works by sensing the airflow. If there is an insufficient amount, the switch will prevent the furnace from igniting and the fan will be running but you will get no heat. It typically operates through the use of a paddle which gets displaced due to the force of fluid moving past it.

https://www.amazon.com/Suburban-2322.../dp/B003G9FZ1G
My SF-30 Suburban heater would run for 15 seconds then shut off. I did some research and saw that the sail switch is a problem in many older units. This part got here quickly. Went in and ran like a champ. Problem solved.

JEagan · 05-02-2021, 03:21 PM

My apologies to the group for going dark for a few days, we were traveling back home from Taos, New Mexico and traveled back to Burdett, Kansas to pick up some wood for my son in Overland Park Kansas and we had no internet access.

Thank you for the videos and links they are great!

But I have news to report - while in Burdett the furnace decided to work !!!
I have no reason why, I had done no troubleshooting on the unit (was saving that for our return to home in Olathe, KS.

The only reason I can think of it not working and then suddenly working is the altitude in Taos, New Mexico - it is at 7000 feet. I am wondering if that was enough to throw off the air/fuel mixture and not allow it to lite.

At any rate I think I will still pull the furnace to clean and inspect

Any thoughts from the group?

I want to sincerely thank all who posted replies the information and advice was super helpful :-)

imnprsd · 05-02-2021, 03:58 PM

Good news. However, I don't know if you really should go to all the trouble of "pulling" the furnace. You know what they say, if it ain't broke don't fix it.

On the other hand, now that you have working furnace, you might start moving some electrical plugs around to see if you can disable the furnace. Then you will find your bad connection that probably just needs to be cleaned with some contact cleaner.

Note: The other day my awning would not go out, but I could hear the motor working when I pushed the "in" button. So I pulled the electrical connections about (located in my forward compartment) and the awning started to work in both directions.

Also, weak grounds cause lots of problems, and there is no harm done to add a good ground vs. trying to find the weak or dirty ground connection.

Morich · 05-02-2021, 04:39 PM

Good to hear it works but then bad to not know why!!
But that is also a point where you can go to the flow chart and look to see how close to working it was----assuming that you were hearing the igniter and smelling gas.
If you get gas and are flicking a lighter in the same are, you do get fire in almost all cases!

So what can happen that changes the result from no fire to getting fire?

The idea of air to gas ratio seems way too far to go for me as there is likely to be some small point, even near the edges of the gas cloud where that mix is correct enough to light as it is not a really critical mix. If it is off, you get smokey orange flames which are not real nice but still light. Most of the time we get too much air as it's so easy compared to limiting the air supply.
A check for that would be to look at the air mix gizmo and see if it is loose. But then it would not be out of reason to think driving a few bumps might shift any of the small parts like the igniter, around so they might wind up in the correct spot. A 1/2 inch out of place is easy to see if it is about to far off!

Also a gas valve that is a bit sticky might be easy to imagine, also, so if it is moving a little any you try it 5-10 times it may break loose and fully open on try number 11.
So there is a chance it has fully fixed itself!

But if one wants to avoid a cold night in the future, looking over the manual and going to page 37 for how to check and adjust the igniter through page 39 where they tell how to clean, might be a really good thing to do.

It mentions cleaning yearly but I'm betting there not many that get that great care.

One easy thing if the right gear is on hand is to either use a shop vac to suck or leaf blower to blow through the vents to see what might come out! Getting a few years collection of gunk out of the heater is almost always a good idea! I'm betting like 80/20 that it has never been done on your favorite furnace!

Always good to wiggle any wiring you get near just to rub off any corrosion potential.

JEagan · 05-07-2021, 01:23 PM

Just wanted to provide an update on the Furnace issues. I spoke with the Suburban Service department and they said that at the elevations we were at the furnace could have used a larger orifice - one for the SF-35

Assuming I would replace the orifice I pulled the furnace and took it apart finding numerous issues. The first being that the existing gas orifice was partially blocked and the manifold tube was full of debris. The two pictures I have included show that pretty well. It is amazing that it worked at all with the orifice blockage

I also found that the burner body in the burn chamber was only held down with one screw - thus the rattling noise I heard every time the furnace came on. I ordered a furnace tune up kit (new sail switch, limiter switch, burner assembly, igniter electrode & manifold gasket), new manifold assembly and new orifice from PDX RV Parts. All told it cost $142, much less costly than a new furnace or a furnace core. We will see how it does when I get it all back together and installed.

Once again just want to thank you all for the input and support

Morich · 05-07-2021, 02:43 PM

Okay, that certainly looks like a good reason for the poor thing to not be able to work just right. That orifice is supposed to be a tiny little hole but you had a hole with a big rusty flake in the middle! That is logical to say the flame would not be real good and might tend to go out!
Not too bad for a furnace that is 14-15 years old to take a $150 or so to put back in shape.
I take a whole lot more to keep me in shape!
We used to live/work in Shawnee-Mission but that was way back when you had to drive out through the country to get to Olathe!

One small item if you still have it torn down and want to head off future trouble would be to add a screen over the two vents to keep spiders and mud daubers from building in them and cutting the airflow over the sail switch!

I drilled out the rivets and added screen and then screws to put it back.