Came out today for a no heat call upon inspection I found the nordyne furnace would try to start but when I called for gas the system would shut down. I removed power to the system and tested each limit switch one by one. I found a bad high limit switch. I was able to test it by jumping it out and the system started right up. Was able to get the heat going for the homeowner but the limit switch will need to be replaced. I took a combustion analysis test and received the following readings o2 is 10.4% and the co levels are 24ppm. The supply temp is 128°F. I also recommend performing maintenance on the furnace once the system is repaired. Nordyne furnace model #Kg7sa108c-35c1 , serial #Kgg150444890. Snap disc limit switch L180F-40. Chud will have to return with the limit switch.