Suburban Furnace In Lockout Mode I Troubleshooting Tips

[@patrickstiltner1207]

Thanks Darren! Great video as always!

[@patrickstiltner1207]

Oh! And by the way, Louavule is spelled and pronounced about eight different ways. Born and raised there and even my siblings say it different ways.....house divided. Your pronouncing it correctly in my opinion.

[@jeffsteele1295]

you are one of the best I have ever seen . Thanks for you video

[@montanaboy3777]

Hey Darren!! Another nicely done video there big guy! I have heard of this "Lock out mode", I has assume this was some sort of a electronic board IC chip problem....never knew it was what I was dealing with. For a couple years since I have had this RV Sub 35f I believe...it will run fine for awhile then once in a while I will wake up cold as it is blowing only cold air - so I also have to reset the thermostat off - then on again and sometimes 4 times to get it running again. We just got done with -21 F here in Missoula and it ran fine, last night it finally died & nothing will make it fire up again (Blower does run) but no heat. I will check this out to see if this is what is wrong....My thinking on the electrical paths were way off of what you showed! Your information makes sense and would indicate that the sail switch has failed or is impeded. Thank you for all your generous hard work you do to get this out too us - no telling how many problems you have solved for the general public. Thanks again.......(Get that young camera guy back on the job too) LOL

[@dkbrinlee]

Mine (Atwood/Dometic) seems to go into lock out mode but I’ve recently changed the sail switch. I’ve cleaned the whole thing recently as well. It was doing it before. I’ve swapped the motor too, because it went out and squeaking.

[@alicelindars1613]

Another helpful video

[@davidgahafer3115]

Hello from Louisville. Great information and yes your pronouncing it correctly.😂

[@cruze1953]

Hi Darren. If a sail switch works properly on start-up but intermittantly opens from varying airflow does the furnace immediately fail or is there a time-out delay (such as one or two seconds) before the air/limit fault trips? An example of airflow deviation would be from reduced CFM from a voltage drop from a high current device elsewhere.

[@timf6916]

Good information

[@gabrielkopp2036]

I have an issue with mine..it always worked fine then I turned on the ac for a while now all it does is click. It is a suburban similar the to the one in your video..any suggestions?

[@patrickmelson4745]

Hello! I had water dripping on my furnace and bowing, the 15 amp fuse. Would it be the board shorted out, maybe? Has slightly rusty water marks on it.

[@richardcetz7994]

Hi Darren I have a sf-35 suburban furnace and I first changed the the high limit switch and it worked for a week and then I had to change the Sal switch and it worked for a day. Now it turns on but it just keeps ticking and doesn't want to light. Can you help me with some guidance please 🙏

[@moderndaydrifter4672]

I also got a sf35f and it started out with it lighting and blowing hot air for about 3 min. Then the flame would go out so I would turn it of and start it again in 5 minutes. Now when I turn it on the fan blows but I don't hear it trying to light it just sits there and blows. I don't have any idea what it could be, I did pull it out and cleaned everything and it wasnt even very dirty so I at a loss as to what I should do.

[@RubiksMind]

Hey Darren, you happen to have a spare Suburban SF30 control board? Following your videos I have replaced my sail switch and ignition electrode. I have a 97’ Itasca Spirit RV. Honestly, it probably has the best layout I’ve seen for my furnace. Easy access to everything. I’ve removed and reinstalled probably about 10times now and still can’t get it to ignite. 1. My blower fan doesn’t shut off. 2. The furnace attempts to ignite 3 times, and then just blows. Any suggestions?

[@AdrianJensen-k3p]

Got a question Darren.....I have a suburban furnace that is stuck on heat and got to 91 degrees in camper and wouldn't turn off. Was set to 73 degrees, but it went way over and got very hot inside. Would this be a thermostat issue or limit switch? Thermostat is an RVComfort ZC.......its in a 2020 Flagstaff Superlite.

[@stephanegalipeau3740]

Hello from Canada eh. Love all your videos. I’ve been watching your AC video’s because I removed my AC safety thanks to you. Now I want to use my furnace and I know I don’t have a AC anymore everything is gone because I do t need it. My furnace don’t work and I don’t know how to rewire it so I can run the furnace any pointers you can give or any videos I haven’t seen yet on how to hook the furnace up with out the AC and control box? Thank you in advance 🇨🇦

[@MyRVWorks]

Sure, we do this kind of work all the time. If you look at the furnace wiring, there's going to be two blue wires that leave that furnace. Those two wires will work their way up to where your AC used to be (as soon as they leave the furnace, the manufacturer is going to change the color of the wires. But the important takeaway is it is the two blue wires actually leaving the furnace before they get spliced into the OEM wiring) Below I will include a link for a new standalone thermostat. So, you'll take your two blue wires leaving the furnace, cut them off of the wires that go up to the air conditioner and attach two new wires that will then go to your new thermostat location instead. One wire will be connected to the R terminal and one wire will be connected to the W terminal on that new thermostat. amzn.to/3YTlrFQ

[@stephanegalipeau3740]

@@MyRVWorks thank you sooooooo much. Sounds simple enough thank you again

[@victorsanchez314]

I have a sf25. I’m have a problem with it in the start up. Fan will run and than after 10-20 seconds it shuts off. The sale switch came out good and getting 12v. And it doesn’t go through the cycle were it runs for 30 as a safety thing before shutting off. Can you help on this?

[@justinjanz6554]

I live in a very cold climate in a Grand Design Momentum toy hauler and I was wondering if I can up grade the furnace from an SF-35Q to a SF-42Q as they're interchangeable???

[@MyRVWorks]

There may be some information in Darren's seminar notes that might help: myrvworks.com/darrens-seminar-outline-for-winter-rv-living-in-comfort/

[@toddallen113]

I have a sfv 35 q furnace. When you turn it on you can hear it click but it doesn't come on?

[@rscott16384]

How does the sf-35 sense flame. My furnace sparks a lights for a second then shuts off after run out.

[@christinaedwards8431]

I have a 2003 sf20 and it was working fine then i woke up to a sound of like a jet outside but it was my heater i turned it off fast and turned off all gas and elc to my hole rv. And it took a little to turn off . But after it did i checked to see if it was plugged or blocked or anything and found nothing. So later that day i turned gas and elc back on and tried it and it clicked but no fan or heat . Help me if u can please .

[@lewisledger8359]

my plug in to my sf35 does not have a blue wire. just red, brown, and yellow. the two blue wire go to the on and off switch. the one you are working on has a blue wire going into the control board plug? help lewis

[@taber1969]

I have a 17' Grand design that ran out of LP-i purged the air and burners light but now NO clicking or furnace start up AT ALL.... Am i missing a safety switch/reset?? Did turn furnace on/off few times but not a peep!!! Ideas? Thnx Darren! PS- Total noob here ....

[@boopme100]

We are in Nevada traveling. Our suburban furnace in our 1996 chevy roadtrek 210 was working great this morning. We traveled for several hours then camped that night. Our furnace would not come on at all. No attempt at lighting , nothing. We were trying to use it off of our house battery. Any suggestions would help.

[@MyRVWorks]

You first need to determine if you have 12 volts power feeding your furnace, it could be something as easy as a fuse. But if you have a call for heat from the thermostat, listen for a slight audible click coming from the furnace. That wouldn't indicate that the small relay on the furnace board is trying to make the fan start. If you do not hear a little click coming from the furnace, it could be a stuck sail switch inside the furnace blower housing. In that instance you can try to tap on the furnace to see if the sail switch will unstick itself. Or you might need to pull the furnace out to access a sail switch, there may be lint, dirt or dander caught inside the arm of the sail switch. Good luck and stay warm!

[@pattyporte539]

😢 help I'm trying to help my elderly neighbor with her suburban p-40 furnace park model. Changed sail switch and igniter. What next please help. Live in Flagstaff Arizona.

[@scottsheffield2594]

When you put the furnace back in the camper do you need to put thread sealant or yellow Teflon on the gas fitting or is it ok since it’s a flare fitting?

[@stevegriffin2626]

On a Flare fitting the threads don’t make the seal. It’s the two mating surfaces of the fittings that make the seal

[@Alaskanoutdoorz]

So if the blue wire doesn’t get energized, and the thermostat is good, does that mean the circuit board is toast?

[@heathercain1321]

Mine clicks but won't start when I turn the thermostat off and turn the fan mode to on instead of auto I hear the fan when I have the thermostat on and the fan mode set to auto I get nothing just clicking.

[@heathercain1321]

My model is the SF-35SF on my 2013 keystone sprinter

[@pattyporte539]

This is Flagstaff again.the fan runs but it won't ignite no clicking at all.

[@MyRVWorks]

If the blower starts but you're not getting any clicking, that would be an indication that the board did not detect either the sail switch changing state from open to closed or the high temperature switch is stuck open . Those two devices are wired in series with each other. Identify which wire is coming back from the thermostat, follow that circuit (12v) through the sail switch and the high temperature switch and then into the control board. You should have 12 volts at the control board once the blower starts and the sail switch is made.

[@pattyporte539]

Ty I'll try that.

[@tomtreece3224]

Is that an sf-25f if so I’m having a hard time finding a circuit board any suggestions?

[@Hj61S827]

Did you find it? There is usually a screw that holds a shroud containing or holding the board.

[@kyleshackleford289]

You're a beast bro

[@Matthewc11v28]

Where do I get a data logger?

[@MyRVWorks]

The ones we use are on our Amazon Store here: amzn.to/3Y9wl9Q

[@russellrustin1028]

My thermostat controls ac and furnaces. I get a click on both but nether comes on.any suggestions

[@jerrym1070]

Did your blower come on ?

[@jerrym1070]

Sounds like blower comes on first ( purge ) , then sail switch closes . I would say exhaust/ inducer motor should come on after purge Cycle , then igniter energizes if no safties are tripped , then gas valve relay clicks . furnace fires off if there us gas and gas valve is ok . Then some type of flame sensor must prove the board that there is flame , if not gas valve drops gas supply . If fired off and flame sensor makes . Then blower kicks on . That's is basic sequence of operation of a gas furnace . Hope that helps . Must be repaired by qualified mechanic usually . Kinda tricky . Video explains a lot . Those sail switches desinigrates and fail over time would be my guess . In the residential world , the sail switch disappear before I started hvac in early 90's . Think I seen 2 or 3 in 30 years . But they still use them in rv heaters apparently

[@russellrustin1028]

The fan doesn't come on I click when I turn it on and when I turn it off both ac and furnaces

[@jerrym1070]

Good luck

[@jerrym1070]

@@russellrustin1028 research sail switch . Looks like a fly squatter with clear plastic on it . Usually the clear plastic fails , it catches the airflow to prove blower works .could be blower motor ( my gut at a guess )

[@chuckmccracken4100]

What if you RV does not have a thermostat in it but it has well I’m gonna call with the furnace but instead of coming out straight back out of the back of the unit it comes out the side in through here I do not know how to send you a picture of what it looks like on the 1976 Toyota Chinook

[@brianbiggs3484]

👍👍🇨🇦✌️🇨🇦✌️🇨🇦👍👍

[@hillbillyrv]

Data logger? Please get hold of me. You have my number.

[@steveanderson890]

I want to know as well!