Furnace Won't Ignite

[degadoodle]

Hello,
We bought this 1999 Gulf stream Sun Voyager last year and are learning the ropes slowly. We tried to use the furnace as its still in the 40's at night up here in Mn. The fan blows, but no heat comes out of the vents. No vents are blocked and the batteries are charged up. We have propane and the other appliances are operating fine.We are on shore power. Any suggestions?
I have looked back on some of the old threads but am not really finding any answers.
Thank you, Cinder and Oly Olson

[Waiter21]

Welcome to the Forum.

make sure the stove lights, This will ensure you have propane pressure and the propane lines are purged of air.

Listen very carefully when you turn on the thermostat. This is the normal sequence:

1) The fan comes on and goes through a purge cycle.

2) About 15-20 seconds later, you should hear a click as the propane valve opens.

3) The igniter turns on and the propane should light.

Common problems

The controller must sense the blower is running. It usually does this with whats called a "sail switch". If the air velocity isn't high enough, the sail switch won't activate and the controller thinks the blower isn't running.

Look up inside the exhaust on the outside, sometimes critters like to set up housekeeping and this blocks airflow.

Thefan comes

[degadoodle]

Thanks, I'll check that out. I'm not sure where or how to investigate the sail switch though.
Cinder

[Persistent]

Originally Posted by degadoodle

Thanks, I'll check that out. I'm not sure where or how to investigate the sail switch though.
Cinder

The sail switch (wind switch) is inside the furnace near the blower. The air flow from the blower deflects the switch and tells the controller board there is enough air flow to light the furnace. Any thing that reduces air flow can prevent the sail switch from working.
Intake for burner may be plugged.
Exhaust may be plugged.
The sail on the sail switch may accumulate stuff on it.
Heat ducts may be closed or plugged.
Return air may be blocked.

The gas to the furnace may be turned off. My furnace does not have a shut off valve, but yours may.

Igniter may be corroded and so not making spark.

[degadoodle]

Thank you.
That gives us some things to rule out. When it stops pouring outside.

[mike toon]

Who made the furnace.
there isnt much to these furnaces.There are some items that can be cleaned first .There is a light that flashes the code .Spend some time and look for the manual for the furnace.Hope this points you in a direction.These are really easy units to fix.

[firedoc]

You said that the fan runs but no hot air. In that case the sail switch is fine. Look elsewhere.

[EdBoz]

Originally Posted by degadoodle

Thanks, I'll check that out. I'm not sure where or how to investigate the sail switch though.
Cinder

If your furnace is an Attwood/Dometic - -

http://www.youtube.com/watch?v=-g3_Y7MqChE

[degadoodle]

Thanks everyone for the great info. Its so nice to have this support.
We are going to look at it today as it seems like we will get a break in the rain. And now a leak has developed above the dashboard (heavy sigh).

[degadoodle]

Hello,
Well, the furnace is a suburban. We checked that the sail switch was clear and basically blew on a few connections and tried it again and it started right up. Don't know what happened there, but we will take it! We learned a little more which is good too.
Thanks again for all the info.
Cinder and Oly Olson

[Old-Biscuit]

Originally Posted by degadoodle

Hello,
Well, the furnace is a suburban. We checked that the sail switch was clear and basically blew on a few connections and tried it again and it started right up. Don't know what happened there, but we will take it! We learned a little more which is good too.
Thanks again for all the info.
Cinder and Oly Olson

Your sail switch was most likely dirty or stuck....messing with it freed it up


Fan starts when t-stat contacts close
Sail Switch MUST close in order for DC to go to circuit board.

Without sail switch closing NOTHING else but fan running can happen.