Suburban Furnace will not stay lit

[Lanexa]

I have a 2004 Sandpiper camper with a suburban furnace that will not light or once lit, will not stay on. When I turn the thermostat up and the fan comes on I go outside where the two vents are and place my hand over the vent that takes the air in and it will light but once the temp inside the camper come up and the furnace shuts down it cannot light again unless I put my hand over the vent again. Any suggestions?

[APhotoWizard]

I would suspect you have a defective sail switch. This switch must be open before the ignition sequence and closed afterwards. (Or the reverse, I forget) Putting your hand over the outlet changes the air flow which giggles the switch into working one more time.

They are relatively easy to replace (After you finally get the furnace out of the rig). Download the manual from the manufacturer.

- Jerry

[nosticks]

Sail Switch.