suburban nt-30sp furnace - not firing

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caliwebman

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Jan 27, 2019
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Hi all, jut bought a 1987 Southwind Eagle by Fleetwood and she came with a suburban NT-30S furnace. It seems that no matter what I do, whether by start up processes and sequences, replacing of igniter, etc that I cannot get this furnace to spark. Finally I tore it out and found that it looks a bit rusty, does make a little squeaking when the blower is running, and now after reading a bit around the internet on this version furnace I have a strong inclination that it may very well be the control board. Or perhaps the blower is not blowing the correct amount of air and a lubrication might assist?

I have a multi meter, just not sure where to begin. Any thoughts, tips or tricks anyone can offer would certainly be much appreciated.

Scott
 

Ernie n Tara

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May 16, 2009
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Ft Myers, FL
Monitor the Voltage at the sail switch with and without the fan. If the switch operates, and the wire to the control board is good that narrows the suspect list significantly. Remaining are the ignitor and connector TV icons. I'd then check the gas switch for operating and both that and the igniter for good connections to the control board.

Ernie
 

Gizmo100

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Sep 28, 2018
Posts
3,029
Welcome to the forum Scott

The first thing I would do is clean each connection to the circuit board. Remove and reinstall everything that plugs into the board. If the board fits into a slot remove and reinstall it as well.

Then as Ernie stated check the sail switch to see if it working.

While your in there clean up the burner. A soft wire brush and a vacuum will do wonders
 

Lou Schneider

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Mar 14, 2005
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11,791
Hi Scott, welcome to The RVForum!

The sail switch is the key to whether the furnace ignites.  A blower that doesn't move enough air to trip the switch, either due to mechanical binding or low voltage, or an obstruction in the intake or outlet air that reduces the airflow through the furnace can keep the switch from activating.

Note that the sail switch is on the inside air half of the blower, not on the combustion side that exhausts outside the rig.

A blockage in the combustion intake or exhaust can prevent the flame from igniting, but if you're not hearing the spark the sail switch on the interior air is the first place to look.

Make sure all of your heat registers are open and unobstructed, and there aren't any kinks in the hoses feeding them.  Also make sure you have a clear and unobstructed path for the furnace to draw intake air from the interior of the RV.  Back when yours was made some RV manufacturers didn't allow enough space for the furnace intake.
 

caliwebman

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Joined
Jan 27, 2019
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2
Location
Left of West
Wow! Thanks a lot you guys for all the responses and the awesome speed at which you all have helped. It looks like I have my work cut out for me with having so many variables involved, will try and spent some good time going through it and report back here with results...... fingers crossed.

In Apreciation,

Scott
 

kdbgoat

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Joined
Apr 16, 2014
Posts
6,329
Here's a link to a straight forward troubleshooting guide written by Gary the Wizard, a member here:

http://www.rvforum.net/joomla/index.php/16-rv-how-tos/333-furnace-troubleshooting

Just so you know, there's a ton of great information in the site's library. Just click on the library tab above.
 

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