I'm having issues with my furnace. It's an American Standard model number TUE080A936K2 and serial number P022W942G. It gave me some trouble (would not ignite) about a year ago. I disconnected and reconnected the wires/plugs and it worked fine. I'm having the same trouble again and tried the same solution. It worked, but only temporarily. I noticed the igniter would come on and light the burners, but then it would go out after a minute or two. There is a code showing (4 flashes) indicating open high limit device. I replaced both high limit switches on my furnace and I'm still having troubles. Does anyone have any advice?