View Full Version : Suburban DYNA-TRAIL Furnace Problem

11-01-2010, 06:12 AM
Well, my wife and I have spent 2 nights in our new home--a 1987 Fleetwood Southwind, and I have figured out how to: operate the water heater (on the second day I finally found a water valve that fills the water heater!) light the pilot on the refrigerator, and connect the sewer line, freshwater line, AC power, and cable. However, I cannot seem to make the Suburban DYNA-TRAIL furnace work.

1. To light the furnace, turn the manual valve to the OFF position and wait five (5) minutes with the blower running. (Set thermostat above actual temperature to operate blower.)
2. After five (5) minutes, set the thermostat to the OFF position.
3. Open the manual valve. (Correct operating characteristics depend on this valve being positioned fully open. Never attempt to operate with valve partially closed.)
4. Set thermostat on desired temperature.
5. Allow 15 seconds for the main burner to light.
6. If the burner does not light, set thermostat on OFF and repeat steps 1 through 5.
7. After three (3) attempts with no ignition, go to shutdown and determine cause.
NOTE: Do not continue to cycle furnace through thermostat in an attempt to
get ignition.

The blower motor is not coming on, the pilot is not lit, the electric pilot is not clicking...NOTHING happens. I found the 12 volt fuse in the electric panel and it is fine. I have futilely searched all over the motor home looking for hidden electrical switch to operate the furnace. Additionally, I have scoured Google for answers without result. I suppose I could contact the previous owner, but I hate to keep bugging him. Does anybody know anything about this? Is there a hidden switch somewhere?
:wall: :hammer: :bag:

11-01-2010, 08:51 AM
Time to head SOUTH Chris, we're not using the furnace. :waggle:

JIM :fire:

Andy N1ORK
11-01-2010, 09:16 AM
6. If the burner does not light, set thermostat on OFF and repeat steps 1 through 5.

Did you move the lever to off all the way? If I remember, the lever needs to go into a 'notch' before it is OFF.

11-01-2010, 05:56 PM
Did you check for 12 vdc on the furnace control board and the T-stat? You may have to interupt the 12 volt once the furnace has hit the lockout point to reset it. Are you currently near the Hill Country of the Republic of Texas?

//John Canyon Lake Tx.

11-01-2010, 07:58 PM
On my Suburban furnace (that's 20 years newer than that one) there is a rocker switch on one side of the unit. You have to squeeze your hand in between the cabinet work and the unit to find it, there is a bundle of wires that plug into the unit very near the switch.

If my furnace acts up resetting that switch will usually straighten things right out.

But I suspect this in no way applies to your unit.

I would call the previous owner. If I had sold you the MH, you would not have left the yard with out a thorough walk through of all systems. And I would have pointed out all the things that require "attention" like doors that have to be bungee'd shut, lights that won't work, stuff like that.

But that's just the way I do my business.

11-01-2010, 10:09 PM
After testing the t-stat and the power converter panel with a volt meter, I found that there was no DC voltage from three fuse blocks. After a phone call to a local RV service technician I learned that the half of my power converter that provides DC to the heater, the water pump and charges the house batteries is toasted. Most likely because the house batteries needed to be replaced for a long time and the coach had been on AC power resulting in the charger being overworked.

Long story short...as a temporary fix I disconnected the house batteries and ran a jumper from the good side of the 12 volt supply and now I have heat. Soon the converter and house batteries will need to be replaced for about $500.

11-01-2010, 11:18 PM
Great! Now you can get a modern charger that will not overcharge your batteries.

Could have been worse...

The nice thing about RV's is they are so modular and share so much in common from brand to brand. And as you repair issues as the come up, you know it's being done right and now will be just as up to date as any new rig.

Keep us posted.

11-02-2010, 05:29 AM
Radio, that is an extremely positive way of looking at things!

11-02-2010, 03:06 PM
If you've got to replace the converter, you might want to look at something like a Prosine 2 inverter. The Prosine puts out 2000 watts of true sine wave AC and up to 4500 watts for surges (ie: motor starting). It also puts out up to 100 amps at 12 volts for recharging the batteries and has a 30 amp power transfer switch built in. (You need two Prosines if you have 50 amp house wiring.)

They sell for about $1,600 new, but can sometimes be found on Craigslist for around $700-800.

I'm in the process of installing a Prosine 2 and three 120 AH AGM batteries into the space under one of the dinette benches in my Travel Trailer. Part of the project is also putting a Honda 2000 (2kw) inverter generator into a box on the back of the TT.

The generator won't start the compressor in the AC, but will run it. (Adding a soft-start cap is yet another project on the to-do list...) The idea is that the Prosine will automatically switch in to start the compressor and then switch back to the generator to run the AC.


11-02-2010, 03:48 PM
BTW, welcome K4AC to ORR.net forums. :hi:

11-03-2010, 02:36 PM
To keep your batteries charged and a power converter, look at the IOTA line.


11-05-2010, 08:10 PM
The heater quit again and I have fixed it again. This time was the same symptoms as last time...no fan, no burner, no electric pilot, but this time there was 12 volts at the t-stat and at the electrical connection at the furnace. I found a wealth of information on the internet to help me troubleshoot the problem. Turned out that the time delay relay went out. I found the part at Stater's Acres locally in Amarillo and they didn't even charge me for the $20 part! After researching, troubleshooting, removing and reinstalling the furnace I have had a real crash course in RV repair! I love it when a plan comes together.

Now to fix the water heater that also quit today...:wall:


11-05-2010, 10:09 PM
Did that rig sit unused for any length of time? These sound like "lack of use" issues.

11-07-2010, 06:45 PM
It's a 1987 model with 29k miles...it has sat a lot.

11-12-2010, 12:08 PM
More frustration--now the heater is working well...when it works! Most of the time the heater is functioning properly, but occasionally, the burner does not light and the blower continues to blow cold air and does not stop until we wake up freezing. Once the heater is shut off for a few minutes, it will light correctly. I replaced the sail switch, and the limit switch, and I removed the burner and cleaned all of the debris with a vacuum. But none of this has fixed the problem. It still occasionally does not light and the fan continues to run. There is not much left to replace. My next step is to replace the ignitor, and if that does not fix it, I guess I will replace the circuit board.

11-13-2010, 09:40 AM
If you are getting no action, THen you need to chase power.

You have two choices, Start at the blower motor or at the battery and measure at each connection/relay, fuse or switch, till the meter changes from either no voltage to voltage or the other way around.

Normally for this kind of trouble shooting I use a test lamp..
I took a blade type license plate lamp socket (HELP counter at any auto parts store, HELP is a brand name) and extended one lead, put in a dash lamp size bulb (it fit) put clips on the ends of the leads.. Hook one to a known good ground then touch the other to the test point.. LIGHT=Power, no light = no power

When the light either comes on, or fails to,, the problem is between the last two points.. If the light comes on on the blower motor itself, then the problem is either

1: Motor ground connection or 2:Motor itself.

If the light fails to come on when touched to the battery the problem is either 1: Battery ground (MOve ground clip to negative terminal of battery to test) or 2: Battery is dead.

NOTE: There is often a 2nd fuse on devices like this.. Not only is the power feed to the furnace fused.. but there may be a fuse at or near the furnace. (Belt and suspenders anyone) usually one is larger so it should never blow.. but fuses wear out believe it or not.

11-20-2010, 08:07 AM
After wrestling the Suburban in and out of the compartment it is installed in to replace parts for the various problems the heater is experiencing, and after discovering through research the inefficiency of the Suburban heater, I have decided to scrap the whole thing and install a catalytic heater. At the advice of a local ham, N5RNY, (also an RVer and truck driver) I learned that the Suburban heater is only about 50-60% efficient (half of the heat energy is lost through the exhaust) where a catalytic heater is about 98% efficient and requires no electricity to operate, although a small electric fan is probably a good idea. Also, the catalytic heater is much safer. I am not quite ready to install the new catalytic heater yet since the money fairy has not visited lately, and I would like to do some more research before I start cutting into my propane lines, but I do think that catalytic heat is the way to go. The link below is a decent article about catalytic heater installation:

Quick and easy catalytic heater installation (http://www.rvboondockingnews.com/2009/11/quick-and-easy-catalytic-heater.html)

I think I would like to do more of a permanent installation than the one described in the article above. The compartment where the Suburban furnace is now would possibly be an ideal location.

Here are some more great articles:

Alternative Heat Sources for an RV
Catalytic, Ceramic, and other buzzwords (http://www.damouth.org/RVStuff/PortHeat.shtml)

RV Catalytic Heater for Little Money! (http://vagabonders-supreme.net/olympian.htm)

Bill Baxter
11-22-2010, 04:17 PM
When you replace the converter make sure you get a three stage charger, The older style, and cheap, units are ferroresonant design. As the voltage rises to fu;ll charge that unload the circuit and the voltage stays high. And that cooks the batteries. Not much diifference in price but your electrical equipment and batteries will thank you for a good charger.

11-22-2010, 04:50 PM
Thanks for the advice Bill. I will keep that in mind. I plan to be on shore power for a while, so repairing the charger/converter is going to have to take a back burner to replacing the furnace with a catalytic heater. Please pardon the terrible pun!

11-23-2010, 09:46 AM
Keep in mind that your control circuits on all remaining RV systems work on 12VDC, the charger/converter is very important consideration. Keep an frequent check on battery water levels, I had one explode last year before changing out my original charger in 2K Winny MH. // John :2cents:

11-25-2010, 07:00 PM
Keep in mind that your control circuits on all remaining RV systems work on 12VDC, the charger/converter is a very important consideration. John :2cents:

Brilliant! I boosted my house batteries with my toad, and the water heater started working instantly. While taking a hot shower after 3 weeks of cold showers :jitter:--I thought about it a little more, and it is quite likely that the sporadic furnace problem (blows but no heat) is a symptom of the same issue. I intend to replace the house batteries and the charger converter next payday. The charger I have now is a Charge Sentinel 15 amp supply which is no longer in production. I plan to replace it with an Iota DLS-15 15 AMP POWER SUPPLY/CHARGER (http://www.google.com/products/catalog?q=DLS-15+15+AMP+POWER+SUPPLY/CHARGER&hl=en&rlz=1T4TSHB_enUS348US351&prmd=ivs&resnum=4&biw=1259&bih=599&wrapid=tlif12907366147991&um=1&ie=UTF-8&cid=10123809191679355003&ei=EBTvTIm4FMmr8AbF7M2aDA&sa=X&oi=product_catalog_result&ct=result&resnum=1&ved=0CEAQ8wIwAA#). Does anyone have any thoughts on this? Should I use a higher amperage supply?

Thanks for all of your helpful advice. I will post the results when the 12 volt systems are repaired.

11-25-2010, 08:08 PM
One thing to keep in mind is that electricity is probably cheaper than propane for heating (especially if you're not getting charged for electrical usage in the park you're at...). I've got a 1500 watt electric heater stowed in the TT for those occasional times we need heat. (I probably need to add a second one as my XYL prefers it to be warmer.)

I set the furnace to about 60 and let the space heater take it from there. That way if it gets really cold outside, the TT temp never gets lower than 60. Down to around freezing, the furnace only comes on very occasionally at night.