Suburban furnace won't light

[trader_reed]

From: trader_reed

My '71 D-20 4X4 has a new Suburban furnace w/electronic ignition. It was working great till I left the heat on the last two nights.
Here's what it does and now doesn't do. When you turn the thermostat on the fan kicks on like normal but after a few seconds the igniter doesn't make that fast "click click click" sound and the fan runs for about a minute then just shuts off.  Turning the thermostat off then on only restarts the cycle. This is what I do know 1) Happens on battery,. and shore power 2) Plenty of LP, Just filled one bottle and stove and fridge work fine. 3) Model NT-24SP.
I'm very handy with tools and fix most things in my house. Is this going to be easy or should I take it somewhere.

Matt

[DaveVA78Chieftain]

Sent: 4/23/2005

Being left on would not hurt it.  It's designed for that type of operation.  Something failed.  The ignitor board is shutting the blower off because it did not detect ignition and prevent running the battery down.  Old style ignitor boards and pilot models units do not have that feature (battery save).

Could be any of the following:
Improper adjustment of ignition probes (1/16").
Loose or corroded connections inside unit.
Ignitor board is defective.
Obstruction (wasp/bird nest in outside duct).in combustion air path not allowing enough air to enter/exit resulting in the sail switch not engaging (blower wheel not turning fast enough).
Sail switch is sticking or defective.

When running on battery, a low battery can cause this because the blower motor is running to slow.  Newer ignitor boards also monitor battery voltage and will prevent operation if battery to low.  Corroded connections can cause a low voltage situation.

Dave

[Slantsixness]

Sent: 4/23/2005

don't rule out an obstruction on the ignitor arm, like a bug or almost anything non-conductive, can stop the spark. If it was metal (conductive) , you would blow the heater fuse.

Tom

[trader_reed]

Sent: 4/23/2005

Is my furnace in "lock out" How do I reset this?

[DaveVA78Chieftain]

Sent: 4/23/2005

Resetting lockout just requires you to turn the thermostat off for 60 seconds and then turn it back on.

Dave

[trader_reed]

Sent: 4/24/2005

Thanks for all the help, It works fine now. I don't know what fixed it though. All I did was wiggle the LP lines at the bottles. I've run it two dozen times and it's just like new. Just one of those crazy things that happen to old vehicles.

Matt