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Suburban Wall Heater - Nothing happening at all when switched on
One day she works fine, and the next, she's dead.   :(

When I slide the thermostat switch for the Suburban furnace from Off to any temperature (including all the way to the right), nothing is happening.  I checked the 10 amp fuse, and it looks fine.  What should I try next to help with diagnosis?  To be honest, I'm not very handy, but wish to learn and try...

Here's a pic of my Suburban heater, which is the original one put into my 2007 MB.

Thanks,
Eric
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #1 –
Hi Eric. The problem is most likely in the thermostat. Mine has the on/off switch at the bottom. The lever at the top is for adjusting the temperature. Even all the way to the left, that upper lever will still allow the heater to come on if it gets cold enough. Exercising that lower on/off switch, should clean the contacts a little, and operation will be more consistent.
     Your 2007 is eight years newer than mine, so you might have a more up to date thermostat. Someone might have updated it to a digital thermostat. Those have batteries that need to be changed. Double A perhaps, and the internal contacts may need cleaning, or new batteries, or both.     RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #2 –
Eric, I agree with Ron.  There is a simple way to clean the contacts on the thermostat.  (This is NOT for a thermostat with a battery!)
1. Remove the cover.
2. Move the lever all the way left and right while looking at the "works".  You should see a pair of electrical contacts that open and close a tiny amount.  On mine, those contacts are at the end of a coil spring.  If the space between those contacts collects any dust, dirt or other material, it can prevent contact from happening.  So, you need to clean those surfaces.
3. Once you find the contacts, slide the lever to the left, opening them.
4. Take a piece of paper, and tear a strip about 1/4" to 1/2" wide, and as long as you want.
5. Slide the paper into the gap between the contacts.
6. Slide the lever to the right, closing the contacts onto the paper.
7. Slide the paper up and down, so that it polishes the contact surfaces.
8 Slide the lever left to open the contacts, remove the paper, and slide the lever right to see if the furnace starts.

If that worked, you are done.  Put the cover back on. 

If it did not work, there is one more thing to try.  Looking at the thermostat, you can see two wires, usually one red and one white, that are connected to the thermostat.  Take something like a piece of wire, a paper clip, or some such and touch the two ends to the connection points where the wires attach to the thermostat.  Essentially, you are shorting out the wires.  This will not hurt the thermostat or you.  The voltage is low.  The thermostat is just a fancy switch, and shorting between the two wires is electrically the same as turning the thermostat on.  If the furnace starts when you short between the two wires but not after you cleaned and closed the points, your thermostat is bad and needs to be replaced. 

If the furnace does not start when you short between the wires, the problem is either with the power going to the furnace or with the furnace itself.  Remember, a fuse can look ok but still be bad.  Try putting a new fuse in place.  If that doesn't do it, you need a service person.

Ken F in WY
'08 MB
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #3 –
"4. Take a piece of paper, and tear a strip about 1/4" to 1/2" wide, and as long as you want."

The best abrasive for this type of maintenance is currency! Yes, money... take a dollar bill (or larger) to do the job, either whole or cut a strip of what might be a proper length.   ;D
Steve S.
Lazy Bones & Cedar
2004 30'IB (Island Bed)
Yesterday is History, Tomorrow is a Mystery
Live for the day!
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #4 –
A 2007 LD should the digital wall control that operates both the A/C and the furnance.
Does your?
If it has the digital combination control, does the A/C operate nornally?
If it has a furnace thermostat only, it may have been rewired if the A/C had died and was repllaced with a new A/C with controls on the A/C's ceiling outlet. If so, the wall-mounted digital control would not be present.

The furnace has two wires that run to the controller or wall thermostate., If the thermostat doesn't operate the furnace due to ithe digital controller not working, the heater wires can be removed and shorted to test for operation. Traditonally, these two wires ran through a mechanical wall thermostat, being turned on and off as the temperature changes.
In a thread a week or two ago, we discused the same issue with Jon's 06 T/K.

Larry

Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #5 –
Quote from: Larry W  - 
A 2007 LD should the digital wall control that operates both the A/C and the furnance.

Larry
Ours does not. I replaced the original furnace thermostat with a digital one.

Charles
Harvest Hosts + Boondockers Welcome #23975
Escapees SKP #138195
2007 23.5' Twin King
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #6 –
Thanks Ron, Ken, Steve, and Larry!  Your input is greatly appreciated.

I think my LD has a different thermostat than what you're thinking.  Here are pics...

Thoughts?
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #7 –
Quote from: Morgueman  - 
Thanks Ron, Ken, Steve, and Larry!  Your input is greatly appreciated.

I think my LD has a different thermostat than what you're thinking.  Here are pics...

That's an odd arrangement. One I have not seen
You can still test the furnace's operation by jumpering or shorting the two wires that come from the furnace to the thermosat.
If the furnace still does not come on, the problem is not in the thermostat.
The thermostat is nothing more than a adjusable heat sensitve switch.

Larry


Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #8 –
Quote from: Morgueman  - 
Thanks Ron, Ken, Steve, and Larry!  Your input is greatly appreciated.

I think my LD has a different thermostat than what you're thinking.  Here are pics...

Thoughts?
Eric, I recently spent an inordinate amount of time trying to figure out why my furnace would not ignite. Jumping the two wires on the thermostat started the blower, but no ignition. Finally, Ken Fears convinced me it probably was the thermostat. Since I had already bought a new one, I installed it and sure enough, that was the issue. Thermostats are cheap. If that doesn't do the trick, having a spare thermostat is probably a good thing.

Chris
Formerly: 2002 30' IB
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #9 –
"Jumping the two wires on the thermostat started the blower, but no ignition."

It's worth mentioning that there are several other situations where the furnace blower will run, but no ignition will occur.

1. Stuck "sail switch." The way these furnaces are designed, the startup sequence is as follows: first the blower starts up, because there has to be a forced draft in the combustion area (there's a blower there as well, powered by the same motor-driven shaft as the blower that gives you hot air). A paddle and microswitch in the path of the airflow is deflected. The controller cord senses this, knows there is adequate airflow, and only then starts the burner.

In other words, no sail switch deflection, no burner ignition. The sail switch can be blocked or clogged by wasp nests, cobwebs, or whatnot. This is pretty common, especially after the rig has been stored for a while.

2. Low batteries. If the house batteries are discharged far enough, the blower may turn, but at a slower than normal speed that may not be enough to deflect the sail switch. Same result as #1: no ignition.

3. No propane supply. This is pretty obvious: if there's no propane, the blower will come on and the controller board will try to light the burner, but fail.

4. Controller board failure. This is the least likely of the scenarios I mentioned, but it does happen sometimes.

I've listed these in order of likelihood.
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #10 –
Quote from: Andy Baird  - 
"Jumping the two wires on the thermostat started the blower, but no ignition."

It's worth mentioning that there are several other situations where the furnace blower will run, but no ignition will occur.

1. Stuck "sail switch." The way these furnaces are designed, the startup sequence is as follows: first the blower starts up, because there has to be a forced draft in the combustion area (there's a blower there as well, powered by the same motor-driven shaft as the blower that gives you hot air). A paddle and microswitch in the path of the airflow is deflected. The controller cord senses this, knows there is adequate airflow, and only then starts the burner.

In other words, no sail switch deflection, no burner ignition. The sail switch can be blocked or clogged by wasp nests, cobwebs, or whatnot. This is pretty common, especially after the rig has been stored for a while.

2. Low batteries. If the house batteries are discharged far enough, the blower may turn, but at a slower than normal speed that may not be enough to deflect the sail switch. Same result as #1: no ignition.

3. No propane supply. This is pretty obvious: if there's no propane, the blower will come on and the controller board will try to light the burner, but fail.

4. Controller board failure. This is the least likely of the scenarios I mentioned, but it does happen sometimes.

I've listed these in order of likelihood.
Yes, the sail switch is a common culprit. With the outside panel off, after you short the thermostat to make the fan come on, you can quickly step outside and check the sail switch to see if it is "fluttering", thus working - or not. They are cheap to replace. I paid a $100 for a mobile svc call and the tech found a bad sail switch, which even I could have replaced if I'd known what to look for.

Chris
Formerly: 2002 30' IB
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #11 –
So I followed the advice of shorting the two wires, and BAM!...the blower immediately kicked on and blew room temperature air.  I did this several times, and each time, after 90 seconds, it shut down without ever blowing HEATED air.  Despite the lack of HEATED air, I expect that a new thermostat will provide a complete resolution.

So I looked up replacement thermostats, and discovered that they're only $15 (+ tax).  I could choose a fancier digital model,  but we're only weekenders in Southern CA; so, it doesn't get much use, and frankly, I'd rather not deal with AA batteries and pay 2-3x more.  The only odd thing, to me, is that the specs of the new thermostat say that it's 24V, but all of the reviews were 5-star and someone specifically mentioned that the amperage with the 24V was 1.2 amps and it works with his 12V RV without problem.

All of you were a terrific help, and probably saved me $100+ in gas and diagnosis/repair had I drove the LD somewhere for resolution.  So, much appreciated!

Eric
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #12 –
Quote from: Morgueman  - 
So I followed the advice of shorting the two wires, and BAM!...the blower immediately kicked on and blew room temperature air.  I did this several times, and each time, after 90 seconds, it shut down without ever blowing HEATED air.  Despite the lack of HEATED air, I expect that a new thermostat will provide a complete resolution.

So I looked up replacement thermostats, and discovered that they're only $15 (+ tax).  I could choose a fancier digital model,  but we're only weekenders in Southern CA; so, it doesn't get much use, and frankly, I'd rather not deal with AA batteries and pay 2-3x more.  The only odd thing, to me, is that the specs of the new thermostat say that it's 24V, but all of the reviews were 5-star and someone specifically mentioned that the amperage with the 24V was 1.2 amps and it works with his 12V RV without problem.

All of you were a terrific help, and probably saved me $100+ in gas and diagnosis/repair had I drove the LD somewhere for resolution.  So, much appreciated!

Eric
Good show, Eric. That's what mine did when I shorted the wires. Hope it works for you.

Chris
Formerly: 2002 30' IB
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #13 –
Eric, your thermostat is the same as mine, except mine is black.  I know replacing the thermostat worked for Chris, but if the circuit is completed, either by jumper or by the thermostat, the blower runs, then after 90 seconds it shuts off, I think there is a problem with the furnace itself.  Still, $15 for a new thermostat is an easy trial solution.  I hope it works.

Ken F in WY
'08 MB
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #14 –
I just discovered that the 90-second blower was shutting down, because I wasn't keeping the shorting wire (ie. a paper clip) in place.  Duh!!!
 I just tried holding it in contact with both wires for much longer (210 seconds), and holy smokes  :o , the blower stayed on the entire time and somewhere around 100 seconds or so, I could smell the familiar scent of "burn" that often accompanies the early hot air that comes from my heater vents.  Woot woot!  Now, my wife thinks I'm  8) ...

So I'm now 99.9% certain that the new thermostat will do the trick.  Unfortunately, I have to wait about 10 days for it to arrive from the vendor.

Eric
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #15 –
Eric, that's great.  You know what is wrong, and the replacement is both inexpensive and easy to do.

Ken F in WY
'08 MB
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #16 –
Eric, it wasn't clear to me from the discussion whether you tried cleaning the thermostat's contacts. In my experience, nine times out of ten that will solve the problem.

There are two sets of contacts (circled in blue in this photo): the on/off contacts at upper left, and the actual thermostat contacts, located behind a translucent plastic shield at the bottom. Clean both sets thoroughly, then wipe lightly with a contact cleaner such as DeoxIT to minimize the chance of future corrosion.
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #17 –
Quote from: Andy Baird  - 
Eric, it wasn't clear to me from the discussion, whether you tried cleaning the thermostat's contacts. In my experience, nine times out of ten that will solve the problem. There are two sets of contacts (circled in blue in this photo) to clean: the on/off contacts at upper left, and the actual thermostat contacts, located behind a translucent plastic shield at the bottom. Clean both sets thoroughly, then wipe lightly with a contact cleaner such as DeoxIT to minimize the chance of future corrosion.
Thank you, Andy!  To be honest, I didn't try cleaning the contacts even though that was recommended early on, because I didn't know what area(s) needed cleaning on my specific unit, and a replacement was pretty cheap.  Your circling of the precise areas, as well as how to clean them, is something that I will definitely try (even if only for academic reasons given that I have a new thermostat en route).  I'm actually very curious to see if that was all I needed...

All of you are very generous with your time and knowledge, and I sincerely appreciate it.

Eric
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #18 –
My suggestion: clean the contacts of this one. If that solves the problem, great! Then you can save this one as a spare after you install the new one. That's a good strategy with a lot of things such as engine belts: if they're still working but getting old, put on new ones but save the old ones as emergency spares.
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #19 –
One thing is bothering me about this whole deal, is it cool enough inside the motor home to allow the thermostat to call for heat?
Just a thought.

Jon
1994 MB
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #20 –
Good question, Jon! You can test for that by taking the translucent cover off the thermostat contacts and manually pressing them together.
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #21 –
Quote from: JonS  - 
One thing is bothering me about this whole deal, is it cool enough inside the motor home to allow the thermostat to call for heat?
Just a thought.

Jon
Yes, good question.  We discovered this issue when we were at Sequoia National Park a couple weeks ago, and the inside temperature had gotten to the high 50s in the morning, and I tried multiple times to get the furnace to turn on, including moving the temperature set slide switch all the way to the right and leaving it there for up to 15 minutes.  I eventually gave up...
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #22 –
Quote from: Andy Baird  - 
Good question, Jon! You can test for that by taking the translucent cover off the thermostat contacts and manually pressing them together.
As I moved the slider to the right, I eventually saw the contacts "snap" together (like two magnets slowly moved closer to eachother), however, it never enabled the heater to come on.  I still have yet to try cleaning the contacts.  As you suggested, if that works, I'll keep the old unit as a spare.  Thanks for that suggestion!
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #23 –
My new thermostat arrived early.  To be honest, I only made a half-hearted attempt to clean the contacts of my malfunctioning unit, because I didn't have the recommended product(s) for cleaning, and I was anxious to try the new unit.  Unfortunately, I never got the old unit to work, but the new one works perfectly.  So, I'm happy despite not knowing if the old unit is salvageable.

Thanks, again, to everyone for their generosity with information sharing.

Sincerely,
Eric
 
Re: Suburban Wall Heater - Nothing happening at all when switched on
Reply #24 –
Thanks from the future!! I had this same problem and thanks to you all, I found that the tstat was bad. And thanks to my overpurchasing problem, I had a spare in the rig!! This 35 degree night just got a lot more comfortable!
Livin the dream, one nightmare at a time.....

2003 26.50MB, Blue