RV News RVBusiness 2021 Top 10 RVs of the Year, plus 56 additional debuts and must-see units → ×
 

Go Back   Keystone RV Forums > Keystone Fleet | Keystone RV Models > Travel Trailers
Click Here to Login

Reply
 
Thread Tools Display Modes
 
Old 03-23-2020, 06:52 PM   #1
jregalia11
Junior Member
 
Join Date: Feb 2020
Location: bryans road
Posts: 3
Suburban SF-30

No heat. Now I have watched you tube videos.. repaired the furnace once before and this time I am stumped.
I have a furnace that will bring the blower on,purge,then NO spark and then open the gas valve.
I have a new board and new spark igniter installed to eliminate a failed old part. Not a parts replacer but there can only be 3 things really wrong.
Maybe someone can help me.
I have made sure spacing is correct on the spark ignitor. 1/8 inch and also shined the light into the burner to line it up. Checked 13vdc. Now I am not getting any bolts of of the board where the spark ignitor is.
My last guess is the sail switch but... before I order one as a guess... correct me if Iím wrong and that the gas valve would not even open if the sail switch or high temp limit was OPEN. I do know the sail switches are the most common failure tho.
Btw have gas.. and gas pressure is proper.
At least it appears that way with other appliances.
No tick tick tick before the gas valve opens.

Searched for this issue before so sorry if itís a repost but no one seems to ultimately ask the question... will the gas valve open even with a failed sail switch ? I donít think so from what I have read but I could be an idiot. Ha.

Thanks in advanced.
__________________

jregalia11 is offline   Reply With Quote
Old 03-23-2020, 07:26 PM   #2
Roscommon48
Senior Member
 
Join Date: Dec 2018
Location: grand rapids
Posts: 581
Like I suggested to someone else, it could be a number of things. You need a professional to get into it. Or, just start changing things out.
might be the lp regulator or low pressure in tanks as well as the other things.
__________________

Roscommon48 is offline   Reply With Quote
Old 03-23-2020, 07:40 PM   #3
k94x4
Junior Member
 
Join Date: Jan 2018
Location: Rathdrum
Posts: 28
I have the same symptoms. I removed the heater and "bench" tested the unit and it worked. So my conclusion is it is the regulator. I have not had a chance to replace it yet to confirm, but that it's my next step.
__________________
Kent
2004 Ford Excursion 6.0
2017 Outback 328RL
North Idaho
k94x4 is offline   Reply With Quote
Old 03-24-2020, 04:33 AM   #4
jregalia11
Junior Member
 
Join Date: Feb 2020
Location: bryans road
Posts: 3
A regulator would prevent the spark ignitor from sparking? That’s the part of this furnace that I am trying to figure out.
What is my sequence of operation in the board/system that just “close” or “make” for power to be allowed to the spark ignitor.
In my opinion.and experience . and I am an HVAC tech in the residential industry a gas problem does not cause the spark ignitor to not perform properly.
jregalia11 is offline   Reply With Quote
Old 03-24-2020, 05:32 AM   #5
k94x4
Junior Member
 
Join Date: Jan 2018
Location: Rathdrum
Posts: 28
I have read that there is not enough gas pressure to get it to process.
__________________
Kent
2004 Ford Excursion 6.0
2017 Outback 328RL
North Idaho
k94x4 is offline   Reply With Quote
Old 03-24-2020, 05:40 AM   #6
Steveo57
Senior Member
 
Join Date: Dec 2017
Location: Lisbon
Posts: 509
The sail switch is a very common problem. If you don't make up the sail switch it will not try to ignite. There's a LED on the control board that will flash fault codes.
Attached Thumbnails
Click image for larger version

Name:	Furnace Operation Sequence.jpg
Views:	70
Size:	342.3 KB
ID:	25742   Click image for larger version

Name:	Atwood Furnace Fault Codes.jpg
Views:	66
Size:	239.8 KB
ID:	25743  
__________________
2018 Keystone Cougar 22RBS
2020 Ford F-350 XLT SC SRW 6.7l Powerstroke.
Steveo57 is offline   Reply With Quote
Old 03-24-2020, 05:58 AM   #7
JRTJH
Site Team
 
JRTJH's Avatar
 
Join Date: Mar 2011
Location: Gaylord
Posts: 19,607
Here's the "sequence of operation" from the Suburban Furnace Service Manual:

Start
Thermostat Calls for Heat
The wall thermostat controls the operation of the furnace by reacting to room temperature, this allows current to flow through the On/Off switch to the module board. The module board constantly checks for a minimum 9.5 volts. If there is not 9.5 volts, the module board will go into a stand by mode until adequate power is supplied. It will then resume normal operation. Upon a call from the thermostat, the module board thermostat circuit will go active. The sail switch circuit is verified as being open. The blower output is energized.

Blower motor starts.
15 Seconds Purge Cycle
The module board will then verify that the sail switch circuit is closed and motor is up to speed. If this circuit remains open for 30 seconds after the blower motor starts, the module board will go into lock out and shut down the blower motor. The module board checks that the gas valve relay contacts (which are located on the module board) are open before the ignition sequence starts. The board has a pre-purge timing circuit of (approximately 15 seconds). This allows the chamber to purge.

7 Seconds Ignition Cycle and Flame Sense
The module board will energize the gas valve and enable the high voltage spark output to the electrode for 7 seconds of ignition time. The module board will then check for flame sense to verify successful lighting of the main burner flame. Sparking will then be terminated and the gas valve and blower outputs will remain energized. If ignition is successful the module board will monitor the flame sense, sail switch and limit switch circuits, and the thermostat inputs during the heating period. The flame is sensed through the spark wire and electrode. Therefore, it is essential that the electrode is properly positioned in the burner flame.

2 and 3 Ignition and Flame Sense Cycles if Required
3 Try Ignition Board If the flame is not sensed after seven (7) seconds, a second 15 second purge cycle will begin followed by a second Trial-For-Ignition sequence. After three (3) Trial-For-Ignition attempts with no ignition of the main burner, the module board will de-energize the gas valve immediately and blower will run for 3 minutes and then shutdown in lockout. Heating Cycle If during the heating cycle, the limit switch circuit opens and remains open for 5 minutes, the module board will go into lock out and shut down the blower motor. If this occurs, the thermostat will need to be reset for the furnace to operate.

90 Second Shut Down
When the thermostat has reached its set point and the demand for heat ends, the gas valve will be de-energized and the flame will go out. The post purge period of 90 seconds begins. When it times out, the blower motor output is removed, and the blower stops.

The above "sequence" calls for several "safety interlocks" to function properly or the sequence will not move forward.

First, the voltage monitor circuit must sense 9.3VDC. If not above that level, the system goes into "lockout".

Next, the sail switch must be OPEN at the start, before the sequence can begin. Then, during the sequence, when the fan switch closes, the sail switch must also close. If that "two step sequence fails" the system goes into "lockout".

Third, the gas valve control circuit opens the gas valve and starts the ignition sequence for 7 seconds. If a flame is sensed, the system advances. If not, then the next step allows for two additional "ignition attempts". At the end of the third attempt, the system goes into "lockout".

Any of those "lockout sequences" will shut down the furnace and prevent operation.

You should be able to download the Suburban Furnace Service Manual here: http://bryantrv.com/docs2/docs/subntnew.pdf the sequence of operation is on page 24. The pages that follow are extremely important in troubleshooting that sequence. Any lockout will cause ignition failure, so it could be something as simple as a "sticking sail switch" or as "elusive" as an intermittent capacitor on the control board or even a crack in the printed circuit on the board.
__________________
John



2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS
JRTJH is offline   Reply With Quote
Old 03-24-2020, 06:42 AM   #8
chuckster57
Site Team
 
chuckster57's Avatar
 
Join Date: Jul 2014
Location: Modesto
Posts: 12,420
Only thing I think you missed is the limit switch, that is verified before the sail switch.
__________________

2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.

Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.
chuckster57 is offline   Reply With Quote
Old 03-24-2020, 06:53 AM   #9
JRTJH
Site Team
 
JRTJH's Avatar
 
Join Date: Mar 2011
Location: Gaylord
Posts: 19,607
Quote:
Originally Posted by chuckster57 View Post
Only thing I think you missed is the limit switch, that is verified before the sail switch.
Chuck,

If I remember the "yes/no logic tree" correctly, the limit switch is verified closed during the ">9.5VDC check". If the limit switch is open, there will be no "minimum voltage and the system shuts down in step #1. So, even though it's not "stated as being in the start-up sequence" the limit switch is verified closed and functional in "step #1"....
__________________
John



2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS
JRTJH is offline   Reply With Quote
Old 03-24-2020, 07:00 AM   #10
Steveo57
Senior Member
 
Join Date: Dec 2017
Location: Lisbon
Posts: 509
Quote:
Originally Posted by chuckster57 View Post
Only thing I think you missed is the limit switch, that is verified before the sail switch.
True I didn't mention the high temperature safety switch that's in series with the sail switch. I don't think they fail that often though. Have you seen many problems with them Chuck?
__________________
2018 Keystone Cougar 22RBS
2020 Ford F-350 XLT SC SRW 6.7l Powerstroke.
Steveo57 is offline   Reply With Quote
Old 03-24-2020, 08:16 AM   #11
jregalia11
Junior Member
 
Join Date: Feb 2020
Location: bryans road
Posts: 3
Thank you for responses. I did actually speak with tech support and he verified that if the gas valve is opening the. That proves the sail switch and limit switch are both doing as they should.
In my case the gas valve is opening and no spark. In my case he mentioned that if you take the orange wire off of the connector on the board and hold it 1/8 inch from the connector you should see spark. If not then it’s a failed board. Everything else is proving in my case and maybe just a DOA board. Will update it after I replace the board.
jregalia11 is offline   Reply With Quote
Old 03-24-2020, 08:42 AM   #12
JRTJH
Site Team
 
JRTJH's Avatar
 
Join Date: Mar 2011
Location: Gaylord
Posts: 19,607
Quote:
Originally Posted by jregalia11 View Post
Thank you for responses. I did actually speak with tech support and he verified that if the gas valve is opening the. That proves the sail switch and limit switch are both doing as they should.
In my case the gas valve is opening and no spark. In my case he mentioned that if you take the orange wire off of the connector on the board and hold it 1/8 inch from the connector you should see spark. If not then itís a failed board. Everything else is proving in my case and maybe just a DOA board. Will update it after I replace the board.
DON'T DO THAT HOLDING THE CONNECTOR IN YOUR BARE FINGERS while wearing damp socks...Ö
__________________
John



2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS
JRTJH is offline   Reply With Quote
Old 03-24-2020, 09:10 AM   #13
chuckster57
Site Team
 
chuckster57's Avatar
 
Join Date: Jul 2014
Location: Modesto
Posts: 12,420
In my years, the control board has failed more often that both the switches put together.
__________________

2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.

Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.
chuckster57 is offline   Reply With Quote
Old 03-24-2020, 03:19 PM   #14
flybouy
Site Team
 
Join Date: Oct 2011
Location: Joppa, MD
Posts: 5,410
Quote:
Originally Posted by JRTJH View Post
DON'T DO THAT HOLDING THE CONNECTOR IN YOUR BARE FINGERS while wearing damp socks...Ö
That would be a "hair raising" experience!
__________________
Marshall
2012 Laredo 303 TG
2010 F250 LT Super Cab, long bed, 4X4, 6.4 Turbo Diesel
flybouy is offline   Reply With Quote
Old 03-24-2020, 05:54 PM   #15
Ken / Claudia
Senior Member
 
Join Date: Nov 2012
Location: Fruitland
Posts: 2,880
Years ago, a RV furnace went out. I double and triple checked everything I could and finally took the furnace out and to a shop. It was the board. Hours after install and testing still nothing. The new board was also dead.
That time the shop put the next board in it and tested. It worked for years after that. Sure is frustrating buying/installing a new part and having it bad from the start.
__________________
2013 24RKSWE (27ft TT) Cougar 1/2 ton series
2013 Ford F350 4x4 CC 6.7 engine, 8 ft bed 3.55 rear end lariat package
Retired from Oregon State Police in 2011 than worked another 9.5 years as a small town traffic cop:
As of 05-2020, I am all done with 39 years total police work. No more uniforms for me.
Ken / Claudia is offline   Reply With Quote
Old 03-24-2020, 08:43 PM   #16
flybouy
Site Team
 
Join Date: Oct 2011
Location: Joppa, MD
Posts: 5,410
Quote:
Originally Posted by JRTJH View Post
DON'T DO THAT HOLDING THE CONNECTOR IN YOUR BARE FINGERS while wearing damp socks...…
John, reading this again brought up an old memory that made me laugh.
40 years ago when DW and got married we moved into our first abode. Our neighbor was retired from a nearby military base after 20 years of pumping gas. His lack of basic knowledge was astounding. He cut grass in the neighborhood for money. Now this guy was constantly bugging me to help him fix everything from his lawnmower and trimmer to his cars. Wanting to help and be a good neighbor I obliged. So a year of this goes by and I ask him if he could cut the grass 1 time while we went on vacation and thought gee, all the times I did a favor no problem right?

So we return and I go over and thank him and out of politeness asked how much did I owe him. He said his "normal" price so I paid him and walked away without comment. Two days later he knocks on the door asking for help as he can't get his mower to start. I told him I'd be happy to help.

I walked outside, pulled the spark plug wire off the plug and told him wrap his hand around it. Then I told him to place his other hand on the metal cage on top of the motor. And you guessed it, I pulled that string with all my might. When he finally stopped screaming and jumping I said "looks like you got good spark, must be a problem with gas".

He never asked me to fix another thing for the 10 years we lived there.
__________________
Marshall
2012 Laredo 303 TG
2010 F250 LT Super Cab, long bed, 4X4, 6.4 Turbo Diesel
flybouy is offline   Reply With Quote
Old 03-24-2020, 10:30 PM   #17
sourdough
Site Team
 
Join Date: Feb 2014
Location: W. Texas
Posts: 10,532
Quote:
Originally Posted by flybouy View Post
John, reading this again brought up an old memory that made me laugh.
40 years ago when DW and got married we moved into our first abode. Our neighbor was retired from a nearby military base after 20 years of pumping gas. His lack of basic knowledge was astounding. He cut grass in the neighborhood for money. Now this guy was constantly bugging me to help him fix everything from his lawnmower and trimmer to his cars. Wanting to help and be a good neighbor I obliged. So a year of this goes by and I ask him if he could cut the grass 1 time while we went on vacation and thought gee, all the times I did a favor no problem right?

So we return and I go over and thank him and out of politeness asked how much did I owe him. He said his "normal" price so I paid him and walked away without comment. Two days later he knocks on the door asking for help as he can't get his mower to start. I told him I'd be happy to help.

I walked outside, pulled the spark plug wire off the plug and told him wrap his hand around it. Then I told him to place his other hand on the metal cage on top of the motor. And you guessed it, I pulled that string with all my might. When he finally stopped screaming and jumping I said "looks like you got good spark, must be a problem with gas".

He never asked me to fix another thing for the 10 years we lived there.


And there I was, thinking I was "that" guy!
__________________
Danny & Susan wife of 53 years
2019 Ram 3500 Laramie CC SB 6.4 4x4 4.10
2020 Montana High Country 331RL
sourdough is offline   Reply With Quote
Old 03-25-2020, 01:10 AM   #18
flybouy
Site Team
 
Join Date: Oct 2011
Location: Joppa, MD
Posts: 5,410
Quote:
Originally Posted by sourdough View Post
And there I was, thinking I was "that" guy!
I'm betting there's several more of "us" hanging around in here!
__________________
Marshall
2012 Laredo 303 TG
2010 F250 LT Super Cab, long bed, 4X4, 6.4 Turbo Diesel
flybouy is offline   Reply With Quote
Old 03-25-2020, 05:02 AM   #19
German Shepherd Guy
Senior Member
 
Join Date: Nov 2018
Location: Norwood
Posts: 298
"No good deed goes unpunished"
__________________

German Shepherd Guy

2018 Keystone 26RBPR
2014 Suburban 2500, 6L with 3.73 rear

German Shepherd Guy is offline   Reply With Quote
Old 03-25-2020, 06:53 AM   #20
JRTJH
Site Team
 
JRTJH's Avatar
 
Join Date: Mar 2011
Location: Gaylord
Posts: 19,607
I can't count the number of times I've bit my tongue and wanted to do just that.... It's reassuring to know that, at least with that one neighbor, you "made a difference".... Good on ya !!!
__________________

__________________
John



2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS
JRTJH is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Powered by vBadvanced CMPS v3.2.3
Disclaimer:

This website is not affiliated with or endorsed by the Keystone RV Company or any of its affiliates in any way. Keystone RVģ is a registered trademark of the Keystone RV Company.


All times are GMT -8. The time now is 06:34 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
×