Furnace blows but no heat

Travisfaherty · 11-20-2016, 06:16 PM

I have a Cougar 314BHS and cannot figure out the furnace for the life of me. I go over to thermostat and select furnace. Auto. And lo fan. Temp is set up in the 80's. I can hear the fan turn on and the furnace click 3 times like it wants to start. I know I have propane as I have turned on stove and water heater. I even tried another regulator to see if that's the issue.

I'm a complete newbie on trailers but do know how to tear stuff apart and check things. So what and where do I check?

Tbos · 11-20-2016, 06:20 PM

It sounds like you have a spark but may not be getting gas to the heater. After a few tries it normally stops trying. Maybe someone with more experience will chime in with some advice. Good luck.

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Travisfaherty · 11-20-2016, 06:31 PM

Quote:

Originally Posted by Tbos

It sounds like you have a spark but may not be getting gas to the heater. After a few tries it normally stops trying. Maybe someone with more experience will chime in with some advice. Good luck.

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That's what I was thinking thus why I changed regulator. Thought of going straight from tank with no regulator but didn't know if heater would have issues.

**chuckster57** · 11-20-2016, 06:38 PM

DO NOT operate the furnace without a regulator in place.

**chuckster57** · 11-20-2016, 06:39 PM

It does sound like a gas issue. Could be a kinked line, blockage or sticky gas valve. Hard to diagnose via WWW.

B-O-B'03 · 11-21-2016, 11:39 AM

Quote:

Originally Posted by Travisfaherty

I have a Cougar 314BHS and cannot figure out the furnace for the life of me. I go over to thermostat and select furnace. Auto. And lo fan. Temp is set up in the 80's. I can hear the fan turn on and the furnace click 3 times like it wants to start. I know I have propane as I have turned on stove and water heater. I even tried another regulator to see if that's the issue.

I'm a complete newbie on trailers but do know how to tear stuff apart and check things. So what and where do I check?

There is not a lot of information here (furnace type, age, etc), but my furnace (Atwood) would come on, click, light and after a few seconds the burner would go off, after 3 cycles of this it would give up.

The issue turned out to be the electronic control board, it had gotten wet from a leaky drain pipe. I replaced the module and that fixed the problem.

-Brian

malabarbob · 11-21-2016, 12:15 PM

Could be a few things. You probably need professional help to check control board and/or blocked like. Insects have a habit of clogging these lines. Once cleared (if the issue) install an insect screens.

Travisfaherty · 11-21-2016, 06:40 PM

Quote:

Originally Posted by B-O-B'03

There is not a lot of information here (furnace type, age, etc), but my furnace (Atwood) would come on, click, light and after a few seconds the burner would go off, after 3 cycles of this it would give up.

The issue turned out to be the electronic control board, it had gotten wet from a leaky drain pipe. I replaced the module and that fixed the problem.

-Brian

Looked at unit and it's a Suburban SF 30. It's in a 2007 Cougar 314BHS. I bought unit a couple weeks back and it fired up and worked then.

**JRTJH** · 11-21-2016, 06:48 PM

Quote:

Originally Posted by Travisfaherty

Looked at unit and it's a Suburban SF 30. It's in a 2007 Cougar 314BHS. I bought unit a couple weeks back and it fired up and worked then.

The ignitor circuit will not function properly if the battery voltage is low. Additionally, the fan "may" not turn fast enough to close the sail switch, open the gas valve and activate the flame sensor circuit. If you aren't already, try plugging the trailer into shore power and see if the furnace will operate properly (with adequate 12 volt power). If it won't, or if you are plugged into shore power already and know the battery is fully charged, then you've got another problem. It's probably either the control board, ignitor circuit, sail switch or gas valve. Trying the old "replace stuff" approach can get to be expensive, so I'd suggest if you're sure the battery power is adequate and/or you're plugged into shore power and it won't work, it probably would be cheaper to call someone to check it out rather than start buying parts. Good luck

Travisfaherty · 11-21-2016, 07:29 PM

I'm hooked to shore power. Tried it with battery switch on and off and no luck. Guess I'm off the rv shop this weekend.

B-O-B'03 · 11-21-2016, 08:45 PM

Quote:

Originally Posted by Travisfaherty

Looked at unit and it's a Suburban SF 30. It's in a 2007 Cougar 314BHS. I bought unit a couple weeks back and it fired up and worked then.

I googled "Suburban SF 30" and got lots of hits, many youtube videos, give it a shot.

-Brian

jsmith948 · 11-22-2016, 06:39 AM

Please post the resolution of your issue.

Travisfaherty · 11-26-2016, 08:27 AM

So I called my local RV dealer and asked what it would cost to look at this. Well they charge $125 an hour. I'm not an RV tech but am an electrician by trade and in previous career did small engines. Thus I can take stuff apart. So between my knowledge and YouTube I think I found the issue.

I close the sail switch and no spark from igniter. Open and close couple more dozen times and finally a spark. I'm thinking the sail switch failed

**JRTJH** · 11-26-2016, 08:39 AM

If you're not getting the "clicking" of the ignitor, then it's probably the sail switch or the ignition control circuit on the control board. (assuming the battery is supplying 12VDC)

Try the troubleshooting steps found in this link, they may help you isolate the problem further. You're right, it's not a complicated piece of equipment and with the right information/experience, certainly not worth $125 an hour if you're reasonably competent at "things mechanical".....

http://www.bdub.net/manuals/Suburban_Service_Manual.pdf

Travisfaherty · 11-26-2016, 09:07 AM

Quote:

Originally Posted by JRTJH

If you're not getting the "clicking" of the ignitor, then it's probably the sail switch or the ignition control circuit on the control board. (assuming the battery is supplying 12VDC)

Try the troubleshooting steps found in this link, they may help you isolate the problem further. You're right, it's not a complicated piece of equipment and with the right information/experience, certainly not worth $125 an hour if you're reasonably competent at "things mechanical".....

http://www.bdub.net/manuals/Suburban_Service_Manual.pdf

That link is really helpful. Thank you.

dlr40901 · 11-28-2016, 01:36 PM

Had similar issue. Suburban SF30-F. Turn up t-stat, blower would run for about 30 seconds then shut down. Pulled unit (a BIG pain), took home to my bench. Checked sail switch, limit switch, fuel orifice and ignitor. All seemed ok. I also cleaned everything I could. Don't have propane hookup at home, so took to local dealer. They hooked up to propane and the furnace fired up like it should. Service guy said could have been dust, insect or other debris causing issue. By me cleaning and opening it up may have dislodged obstruction. They said it could be low propane pressure to furnace, due to faulty regulator. I ordered new regulator to be on safe side. Best part was dealership bench tested at NO CHARGE!!

rgnmgr · 12-11-2016, 06:52 PM

This seems to be a common issue on the internet for Atwood furnaces. Many of us have or are experiencing this problem. Hopefully you can access your furnace.

Travisfaherty · 12-11-2016, 07:38 PM

Well I called my local dealer and they wanted $125 an hour to work on it. Well the unit is held in by 1 screw, 1fitting and 4 wires. After disconnecting all that I find the toe kick on cabinet won't let it out. A couple more screws and some force as 2 screws were buried I had unit out and on bench.

Looked it over and board doesn't have light so found sail switch and pulled it out so I could trigger it. Opened the igniter door. Hook to battery charger and engage sail switch and igniter doesn't spark. Repeat a dozen times and it's hit or miss and at most it spark a couple seconds. Specs is 7 seconds.

Head to dealer and get new sail switch. First closing it sparks 7 seconds. Needed anew gasket for spark chamber which was on Amazon. Put back in and getting the propane coupling tight is a fun time. Hook it up and turn on propane then spray connection with soapy water. Major bubbles so turn off propane and tighten a bit more. Repeat process. No bubbles. So good to go. Hook up wires. All done.

Flip on thermostat and it fires up and gets really hot. In all I have about an hour in pulling, testing and reinstall. Have another hour in research. And $12 in parts.

**chuckster57** · 12-11-2016, 07:57 PM

Glad you found the problem and got it fixed cheap. Mud dawbers/paper wasps seem to be the leading cause of problems followed by control boards. Sail switch failure is rare.

Travisfaherty · 12-12-2016, 04:34 AM

When I ordered my parts from Amazon I got two round screens for the exterior vents to help prevent flying insects. They install in seconds with a sprig clip. Cheap insurance.

And while at the dealer I talked to the parts guy and they have a board tester. It does pay to go to a local place if you have one.

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