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BigMerc · 10-21-2010, 03:55 PM

My wife and I recently purchased our first Airstream, a 77 31' Sovereign from her grandparents out of Moonstone, Ontario, Canada and hauled it back across the country to our home in the Okanagan Valley, BC. Our first night in the trailer the furnace fired and worked great ( for about 5 mins ) until I realized that we were running of the trucks battery power and should probably check to see if the "old" Rv batteries were holding a charge after 8 hours on the road. Alas they were not and so we shut everything down and spent a chilly night outside of Sudbury. The next day we picked up 2 new batteries and installed them with no issues and everything worked great...except the furnace. I cannot get the blower to come on at all. Have checked the 12v panel and fuses and pulled the thermostat which seems to be working fine...any ideas as to why it would fire up the first night and not at all after replacing the batteries?

Thanks for the help!

Mike Leary · 10-21-2010, 04:16 PM

Is the furnace a Suburban?

BigMerc · 10-21-2010, 05:06 PM

Yes it is a suburban NT30

wasagachris · 10-21-2010, 05:12 PM

Check for power at the furnace. Is your trailer rear or center bath. it makes a difference which circuit the furnace is powered from.

Splitrock · 10-21-2010, 05:16 PM

What elements related to the furnace have you eliminated so far? Does it have gas? 12 volt electric to the furnace? Did you jump the thermostat? Why do I think it's something with the 12 volt?

Gary

Mike Leary · 10-21-2010, 05:29 PM

We've had two, our original and a fresh one a few years ago. I've had huge problems with the new one (tech blames it on us full-timing, what a crock). BUT, I never have had a problem with the fan motor not activating. If you've crossed the wires at the thermostat and nothing happens, that's a possibility of the problem. The only other one I can think of is a broken wire from the 12-volt connection. If the motor shorted, it should have blown the fuse. Do you know which fuse feeds the Suburban, or are all the fuses o.k.? All the rest of
the furnace is heat-related and should not affect the fan. Mine has a disconect block where the thermostat power and 12 volt + & - connect. Check that connection. Good luck.

Lumatic · 10-21-2010, 05:30 PM

One of my 1st suspicions would be the batteries are not charging and the 1st night with the new batteries drained them to the point the furnace won't fire. Other systems in the trailer don't need as much juice as the furnace. Put a voltmeter on the battery, or better yet the power line at the furnace and you should have at least 12.5 v. which is also getting low. 13.5 to 14 is fully charged. If your battery discharge on new batteries is low I would suspect your charger. If you have an original Univolt I would consider getting rid of it anyway as they are notorious for boiling batteries. If your charging system checks out OK , the furnace is original, and the furnace needs anything more than a very minor repair, junk it and get new. Problems with old furnaces can drive you nuts at the least and are unsafe at worst. You can get a new NT 30 for $350 from Palomino

BigMerc · 10-21-2010, 05:32 PM

Trailer is a centre bath...I have 12v to the furnace and gas. Not sure I know what you mean by jumping the thermostat? My first thought was that it had something to do with the 12v because it was after replacing the batteries that everything went awry. I have checked the panel thoroughly however and nothing looks amiss.

Josh

Lumatic · 10-21-2010, 05:37 PM

Quote:

Originally Posted by BigMerc

and everything worked great...except the furnace.

I missed that part first go round. Kind of pokes a hole in my charger/ converter hypothesis, doesn't it?

Also check there is not a 2nd in line fuse somewhere, and the furnace is grounded.

To jump the thermostat just cross the wires.

Mike Leary · 10-21-2010, 05:39 PM

It should have fired with fresh batteries. How do you know the thermostat is working? I've pulled the wires from the housing and connected them to prove the wiring is o.k. Those thermostats are pretty durable, but yours could have gone south.

BigMerc · 10-21-2010, 05:43 PM

Thanks so much for the quick reponses...

Quote:

Do you know which fuse feeds the Suburban, or are all the fuses o.k.?

I have checked the fuses and they are all good to go. I will try crossing the wires at the thermostat to see if I can get the blower to go at all. I have already pulled the cover off and all of the connections/contact looked clean (thermostat). Thanks again for the advise.

Quote:

One of my 1st suspicions would be the batteries are not charging and the 1st night with the new batteries drained them to the point the furnace won't fire.

I don't think that this is the problem. We never had the furnace running at all on the new batteries and so there was never a significant drain put on them prior to our first attempt at firing the furnace post replacement. We had fired the furnace the night before while still running on the old batteries. I will check the power line coming into the furnace with the volt meter however just to be sure.

Josh

wasagachris · 10-21-2010, 05:43 PM

Circuit #4 Brown wire powers furnace. If you have power at furnace check for power at thermostat. If you have power at thermostat connect both wires together and furnace blower should run.

BigMerc · 10-21-2010, 05:46 PM

You guys are quick...poking holes in your own theories and answering my questions before I have even had the time to formulate them...excellent!

BigMerc · 10-21-2010, 05:47 PM

Quote:

Originally Posted by wasagachris

Circuit #4 Brown wire powers furnace. If you have power at furnace check for power at thermostat. If you have power at thermostat connect both wires together and furnace blower should run.

Thanks...I will try this tonight and let y'all know how it turns out!

Josh

ps saw the turnoff to Wasaga Beach while we were in Ontario picking up the trailer!! Must be from around those parts eh!!!