I have a RUUD furnace that stopped blowing hot air last night. I was thinking that it was the high limit switch gone bad BUT the coil ignites and lights but then goes out again after a minute, so since it actually ignites I ruled out that possibility. If the thermostat setting is on AUTO it just keeps blowing continuously (cold air is coming out). I have to turn the setting to OFF in order to stop the blowing. Any other thoughts?
If the blower is continuously blowing, then one of the limit switches is open. It may not be the high limit, but it's certainly one of them. Without knowing more about the unit (model number, photo of the schematic, etc.), it's difficult to offer much more assistance.