Sububan Furnace Issue

gregice1958 · 11-25-2023, 11:32 AM

I'm new to this. I'm trying to ID my suburban furnace in a 2012 Keystone Outback 298RE. Can anyone help?

wiredgeorge · 11-25-2023, 05:21 PM

Quote:

Originally Posted by gregice1958

I'm new to this. I'm trying to ID my suburban furnace in a 2012 Keystone Outback 298RE. Can anyone help?

Welcome. Looking at a the same camper on RVTrader, your heater is under the refrigerator on your unit. You can take off the return (metal grating) and see if you can spot some sort of tag. Some of the folks are more knowledgeable than I and can likely tell you the brand if not the model.

ChuckS · 11-25-2023, 05:28 PM

https://www.trekwood.com/parts-searc...23+%2F+Keyword

If Trekwood info is correct as shown in the link above your Suburban furance is SF30Q

gregice1958 · 11-26-2023, 08:57 AM

Thanks for those who helped ID my furnace, It is a SF-30FQ. The symptom I'm having is all of a sudden it quit working. Everything else at the thermostat functions properly. In heat mode, it clicks down at the furnace when I slide the lever and it hits the room temp spot. I thumped the unit a couple of times and it worked again for a day. All known external circuit breakers and fuses have been checked. It looks like a bear to remove the unit but there is some sort of relay that is clicking in there. Any help is appreciated. Thank you. Greg

wiredgeorge · 11-26-2023, 10:17 AM

Folks with more skills will come along but until then youtube is a source:
https://www.youtube.com/results?sear...e+not+igniting

For future questions to help with context, put a signature and profile together with year,. make and model of your camper and tow vehicle. UserCP; top left of each page and be sure to save.

ChuckS · 11-26-2023, 10:28 AM

The "Click sound" is the blower motor timing relay. Either it is not completing the circuit to send 12 vdc over to the blower motor OR the blower motor brushes, bearings are binding slightly not allowing the blower motor to spin up..

RV Furnaces that don't have the outside access panel are a pain.. The only way you can resolve this issue is to remove the furnace from against the wall so you have access to the furnace control board.

Once you have access you can have a helper turn Tstat to furnace mode while you measure for 12 vdc at the furnace control board Blower Motor board connection terminals..

** If you see 12 vdc each and every time the Tstat is set to furn mode, hear the timing relay CLICK then most likely either you have a bad motor wire connection to the furnace control board or a bad motor.

** If you Dont see 12 vdc at the blower motor connection terminals on the furnace board AND have 12 vdc to the board itself then your furnace control board needs replacing.

Yes - you could solder in a new timing relay.. But considering the "Age" of the furnace I would replace the entire control board if you TS it down to the board itself

NOTE - you can also take two jumper wires and jump from the furnace in coming 12 vdc to the board to the two motor wires ( remove from board connection ) to test the blower motor for spin up

ChuckS · 11-26-2023, 10:46 AM

Image from a PDF I wrote on furnace TS.. Suburban furnace control board for SF series

Red arrow is your incoming "Source" 12 vdc power to the control board. Yellow arrow pointing to BLO connection is the Pwr (12vdc ) connection to the blower motor.

If you have a multimeter and can use it then set to VDC scale and put red lead to BLO connection on the board and black meter lead to chassis ground on the furnace...

Should see 12 vdc when helper turns on the furnace at Tstat.. If you hear the "Click" sound ( relay timer ) but dont see 12 vdc on the meter when connected as above then control board is bad ( could be cold solder joint, failing timer relay, etc ) considering age of the furnace

GlasNav · 11-26-2023, 12:36 PM

This on an 11 year old unit, has the obvious been taken out of the equation? Have rodent type critters or mud dauber wasps fouled or damaged the wiring or mechanisms?

gregice1958 · 11-26-2023, 04:55 PM

Thank you much. It looks like a pain to get it out but it's worth it. Thanks for being specific. Greg

gregice1958 · 11-26-2023, 08:01 PM

Thanks again for your help. Question, do the red and yellow wires that go to the back of the furnace, connect to the red and yellow terminals in the picture diagram you sent? I ask because I have access to those wires from the back panel of the refer and could pin probe them in lieu of at the terminals. I pulled the furnace forward but the wires aren't long enough, so I'll have to cut them to get the unit out and crimp longer pieces to the board to do your tests. Pin probing the 2 wires as is, would be a godsend if I can. Thanks again. Greg

ChuckS · 11-27-2023, 06:40 AM

Quote:

Originally Posted by gregice1958

Thanks again for your help. Question, do the red and yellow wires that go to the back of the furnace, connect to the red and yellow terminals in the picture diagram you sent? I ask because I have access to those wires from the back panel of the refer and could pin probe them in lieu of at the terminals. I pulled the furnace forward but the wires aren't long enough, so I'll have to cut them to get the unit out and crimp longer pieces to the board to do your tests. Pin probing the 2 wires as is, would be a godsend if I can. Thanks again. Greg

I hesitate to answer this due to age of unit and NO Idea of what previous work to that furnace unit may have occurred over the years... if any...

You have four wires going to the furnace... two are 12vdc (+) and 12 vdc (-) that provides power to the control board ... They are always TOO SHORT to have enough room to work on the unit and end up being disconnected via twist caps (usually)

The other two wires that go to the furnace are the Tstat "Signal wires" that complete a 12 vdc circuit telling the furnace board to either turn On or Off to run the furnace.. These two wires will either go to Tstat on older units OR up to Roof AC Zone 1 control board

ChuckS · 11-27-2023, 06:46 AM

Image from older 2013 Keystone Alpine.. furnace is SF42Q but wiring is red/yellow for 12 vdc and ground and two blue wires are signal wires from Tstat to turn furnace board on and off

This furnace is buried under the floor and accessed their basement storage area.

Image may help to clarify your question

Mountain guy · 12-04-2023, 07:52 AM

There is a non visible reset button, on right side of our suburban furnace. It's close to impossible to see but seemed to solve the same problem. We used a marker pen to point to arrow and explanation once it was found.

gregice1958 · 12-04-2023, 08:30 AM

Thanks again. I dove in, tested the wires you mentioned, tested the sail switch, and jumped the blower motor off the battery. I took the board to Caveman RV, it tested bad and they had 1 in stock. What an overall adventure, but I have my furnace back. Thanks again for all your help and concern. Greg

ChuckS · 12-05-2023, 09:18 AM

Nice work with your TS steps.. You nailed the problem down without doing a lot of unnecessary parts swap outs that so many folks do..

The unit should give you good service for a long time now.

** I recommend running the furnace once a month even in the summertime to exercise the blower, sail switch, LP valve, etc on the unit.. It also blows out any critters that may want to make it their home..

Just a couple of minutes once a month is what I do.. even when stored here at the house from Oct to early May each year.

ChuckS · 12-05-2023, 09:20 AM

Quote:

Originally Posted by Mountain guy

There is a non visible reset button, on right side of our suburban furnace. It's close to impossible to see but seemed to solve the same problem. We used a marker pen to point to arrow and explanation once it was found.

Ive note seen a RESET switch on the Suburban SF series units.. the Dometic Atwoods have it ( 15 amp ) resettable service switch located on the outer case of the furnace unit.

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